2000-2001 Report of Tomato Research - Citrus · 2000-2001 Report of Tomato Research ... focused on the tomato industry of Florida. This is an extremely important partnership between

2000-2001 Reportof TomatoResearch

Supported by theFlorida Tomato Committee

Institute of Food and Agricultural Sciences

Institute of Food and Agricultural SciencesOffice of the Dean for ResearchFlorida Agricultural Experiment Station

1022 McCarty HallPO Box 110200

Gainesville FL 32611-0200Tel. (352) 392-1784Fax (352) 392-4965

Email: [email protected]: http://research.ifas.ufl.eduMEMORANDUM

TO: The Florida Tomato Committee

FROM: Mary L. Duryea, Interim Assistant Dean for Research

SUBJECT: 2000-2001 Research Report

DATE: September 4, 2001

This report describes research in UF/IFAS/FAES that received support from theFlorida Tomato Committee during the past year. The Florida Tomato Committeesupport combines with State and Federal resources providing critical operatingsupport that allows IFAS tomato scientists to have a strong research programfocused on the tomato industry of Florida.

This is an extremely important partnership between the Tomato Industry andIFAS scientists. We have worked together to identify the questions and needsfor the industry. Then, again together we have prioritized the research to beaccomplished. This year’s work ranged from methyl bromide alternatives tomanagement of major pests to tomato breeding to analyzing the final productsand their handling. Many of the results are immediately applicable by the industry.Some projects are continuing next year with their findings.

We hope to continue in our quest for improving production methods andproduct quality. We are pleased to have the Florida Tomato Committee as apartner in programmatic support for tomato research. On behalf of the scientistsinvolved in tomato research, we thank you and appreciate your support.

This report of research results is presented in electronic format. We hope you findthe information in the report useful to all facets of tomato production.

MLD:las

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Evaluating approaches for weed andnematode control for tomatoproduction in south Florida

Gladis Zinati, Herbert Bryan,Robert McSorley and Merlyn Codallo

AbstractSunn hemp, a leguminous cover crop

provides good biomass and non-syntheticnitrogen source to cash crops; suppresses weedsand nematodes. The objectives of our study wereto evaluate approaches for weed and nematodecontrol for tomato followed by cucumber during2000-2001. The experimental was split plotdesign with plastic and plant mulch as main plotsand herbicide, fumigants and fallow as sub-plots.The treatments were: sunn hemp, sunn hemp +500lb/acre, sunn hemp with paraquat+diquat,sunn hemp with sencor. The sunn hemp was 2.44m tall with a biomass of 14.7 MT/ha twelveweeks after planting on July 19, 2000. The weedswere better controlled under plastic mulch andsimilarly nematode density was much suppressedunder plastic than without plastic mulch. Tomatoyield was highest in the sunn hemp + 500 lbfertilizer under plastic mulch and was 22% lowerthan that of methyl bromide (58 MT/ha).However, tomato yields in treatments withherbicides and without plastic cover were 40%lower than that of methyl bromide. As for thecucumber, all treatments with plastic mulchprovided similar yields to methyl bromide (23.5MT/ha). Reniform nematode at cover cropmowing and during the tomato growing seasondid not increase significantly, however, theroot-knot nematode increased by the end of thesecond cash crop (cucumber).Introduction

Florida ranks first in fresh market tomatoproduction followed by California. Tomatoproduction in south Florida as in other parts ofthe state depends on methyl bromide as a soilfumigant for controlling weeds, nematodes and

1

soil borne pathogens. As methyl bromide phasesout, alternatives are needed. These approachesmay include chemical, non-chemical or theircombinations. The alternative(s) should beenvironmentally friendly and cost effective. Insouth Florida, during the last two years weevaluated cover crops for biomass, and weed andnematode suppression. We found that ‘TropicSun’ sunn hemp, a leguminous cover crop,provided a good source of nitrogen as well assuppressed nematodes for one season of tomato.This year our objectives were to evaluateapproaches for weed and nematode control fortomato followed by cucumber production during2000-2001. These approaches included the use ofherbicides, plastic mulch, sunn hemp cover crop,and fertilizer.

Materials and MethodsA summer cover crop, “Tropic Sun” sunn

hemp was planted on July 19, 2000 on preformed15 cm thick beds with 1.83 m centers. It wasseeded at the rate of 56 kg/ha using TYE seeddrill (AGCO Corporation, Box 1120, HWY. 70East, Lockney, TX 79241). The sunn hemp wasmowed with a flail mower twelve weeks afterplanting and left on the beds as mulch. Theexperimental design was a split-plot with plasticor no plastic as a main plots, and herbicides,fumigant (M67:C33) and fallow as sub-plots.Methyl bromide:chloropicrin was applied at therate of 280 kg/ha.

Three weeks old tomato seedlings weretransplanted 50.8 cm in-row spacing on bedcenters 10 days after methyl bromide application.The methyl bromide treatment had 1120 kg/ha ofdry N-P-K fertilizer (6-2.6-10). One treatment ofsunn hemp also had 560 kg/ha of dry fertilizer forcomparison without fertilizer. During the growingseason soluble N-P-K fertilizer (4-0-6.6) wasinjected periodically in all treatments through thedrip lines to provide 150 kgN/ha for all plots. Weharvested tomatoes 4 times during the tomatoseason. Tomatoes were evaluated for medium,large, x-large and total marketable yields inaddition to culls.

After the last tomato harvest, paraquat +diquat herbicide were applied on all mulch and inthe furrows to kill weeds before we transplantcucumber.

Cucumber seedlings were transplanted intosame plots with 25.4 cm in-row spacing.Fertigation was continued to supply 112 kgN/haof 4-0-6.6 N-P-K. We harvested 11 times andgraded the cucumber fruits for fancy, grade 2 andculls. The early marketable yield is consideredthe first 3 harvests and the total marketable yieldis the sum of the eleven harvests for the fancyand grade 2.

ResultsCover crop biomass

Sunn hemp plants were 2.44 m tall threemonths (12 weeks) after planting. The sunn hempbiomass was the highest and produced 14.7 Mg/habiomass (dry basis) compared to previous seasonsand years (11.2 Mg/ha (planted on July 11, 98);5.5 Mg/ha (planted on Oct 17, 99).

TomatoData on weed coverage was taken at 5

weeks after herbicidal application, and again 12weeks after planting. Weeds were controlledunder all treatments for 3 weeks after planting.Weed coverage 12 weeks after planting was> 80% in the fallow and sunn hemp plots withoutherbicide or plastic mulch. The major weeds werenutsedge and parthenium. Treatments with plasticmulch had nutsedge coverage of 15-20% at theend of the tomato season and were similar to thatof methyl bromide.

Soil samples were collected at mowingtime, during tomato growing season and sent toRobert McSorley (Gainesville) for nematodeenumeration. Root-knot nematodes were notdetected at the cover crop mowing time, however,reniform nematode density was in the range of50-80 per 100 cc of soil.

Mid of the tomato season, soil sampleswere collected and analyzed for nematodes.Spiral nematodes were 2-3 folds lower in alltreatments with plastic mulch than those withoutplastic mulch. Methyl bromide treated plots were

2

lowest in spiral nematodes. Although root-knotnematodes were not detected yet, reniformnematodes were also found to be lower intreatments with plastic mulch (average of 80 per100 cc) in comparison to those without plasticmulch (90 per 100 cc) but not significantlydifferent. Again, methyl bromide was the lowestin reniform (14 per 100 cc of soil).

There were no symptoms of root-knot gallingon tomato roots at the end of the tomato season.

The highest yield of tomato was 58.07 MT/ha for the methyl bromide with 1000 lb fertilizertreatment followed by that of sunn hemp with500 lb of dry fertilizer (45.12 MT/ha) with plasticmulch cover. In the herbicide treated plots withplastic mulch, the tomato yields were 37.55 MT/ha for sencor and 39.92 MT/ha for paraquat +diquat, respectively. The treatment of sunn hempwithout fertilizer under plastic mulch yielded30.61 MT/ha. The same treatments withoutplastic mulch were 32.60 MT/ha in theparaquat+diquat treated plots, 32.34 MT/ha insencor, 30.61 MT/ha in sunn hemp treatment and28.25 MT/ha in sunn hemp with 500 lb/ha. Thefallow treatment was the lowest yielding treatment(18.88 MT/ha).

CucumberTreatments with plastic cover (sunn hemp

+500lb fertilizer, sunn hemp with any herbicidetreatment) had higher early cucumber marketableyields (7.07-7.34 MT/ha) and were higher thaneither that of sunn hemp (6.67 MT/ha) or that ofmethyl bromide (6.19 MT/ha). On the other hand,treatments without plastic cover were 30-40%less than those under plastic mulch.

All treatments with plastic mulch had totalmarketable yields (21.56- 23.24 MT/ha) similarto that of methyl bromide (23.58 MT/ha).Treatments without plastic mulch were 25% less(sunn hemp alone) and 47% less (sunn hemp withany herbicide treatment or with 500 lb fertilizer)than that of methyl bromide.

At the end of the cucumber season(July 30, 2001) soil samples were collected fornematode enumeration and sent to Gainesville foranalysis. No data yet on the last soil sampling on

the nematode density. However, cucumber rootswere heavily infested with root-knot galls at theend of cucumber season (July 30, 2001) andespecially in treatments without plastic mulch.

Field dayIn coordination with the Miami-Dade

Extension Office, we held a field day on February14, 2001 and invited growers, chemicalcompanies, industry representatives, researchers,and extension agents to evaluate the treatments,give their suggestion and recommendations.Around 25 persons attended the field day andfound it an excellent field day for they were giventhe opportunity to evaluate and give theiropinions about treatments responses and whatneeds to be done for the future.

They were happy to see some advancesand we are addressing the needs of the vegetableindustry in south Florida.

DiscussionResults of this study show that using sunn

hemp with plastic mulch had higher marketabletomato yields than those without plastic mulch.The highest tomato yield was that of sunn hemp+500 lb fertilizer with plastic mulch (45 MT/ha)and was the closest to that of the methyl bromide(58 MT/ha). Weed control was very difficult inplots without plastic mulch. However, the plasticmulch was very useful in controlling weeds.Nematodes were also suppressed under plasticcover than those without plastic cover.

Similarly, treatments with plastic mulchhad higher early and marketable yields than thosewithout plastic cover. All treatments with plasticmulch had similar marketable yields to that ofmethyl bromide.

Weed control continued to be very difficultto control without plastic cover. Root-knot gallingon cucumber roots were very heavy in thosewithout plastic mulch and less in those withplastic mulch.

These preliminary results provide valuableinformation to the tomato growers and vegetablegrowers in general in south Florida to use forfinding alternatives to methyl bromide.

3

RecommendationsThis study provided important

information for the researchers, extensionspecialist and tomato/cucumber growers. The useof sunn hemp as a nitrogen source with plasticmulch and half the fertilizer rate used by tomatogrowers provided highest tomato and cucumberyields in comparison to that of methyl bromide.The cost of sunn hemp is $2.5/lb and at the rateof 50 lb/acre is still cheaper than the cost ofmethyl bromide per acre.

Further studies are needed to evaluate theoptimum rate of fertilizer and irrigation with theuse of sunn hemp or other leguminous covercrop. The tomato/cucumber grower irrigates veryfrequently and due to the type of soil in southFlorida (very low water holding capacity) excessirrigation as well as excess fertilizers are beingused currently and consequently cause losing thenitrogen fertilizer and leaching it to the groundwater.

Moreover, studies on the use of differentherbicides that can be applied with and withoutthe use of plastic mulch and still be effective,without causing phytotoxicity to the cash cropsare needed to be evaluated under the southFlorida environmental conditions.

We submitted 2 grant proposals for theFlorida Tomato Committee (2001-2002) addressingthese needs, and we hope we get granted.

We would like to thank the Florida TomatoCommittee for supporting us to conduct thisexperiment and to provide very valuable informa-tion to the tomato growers in south Florida.

AcknowledgementsThe authors would like to thank the Florida

Tomato Committee for supporting this experimentthat provides valuable information regardingcover crops and plastic mulch effects on tomatoyields, weed and nematode control in southFlorida. Also, the authors are grateful to SeedWay for providing tomato and cucumber seeds,UAP and Helena Chemicals for providingpesticides for this research and to UAP forproviding free lunch on the field day.

4

IPM of Thrips and TomatoSpotted Wilt Virus in Florida

J. Funderburk , T. Momol and S. OlsonUniversity of Florida, IFASNorth Florida Research andEducation Center30 Research RoadQuincy, FL 32351

ABSTRACTWestern flower thrips (Frankliniella

occidentalis) and tomato spotted wilt virus whichit vectors are the key insect and disease pests oftomato in northern Florida. Insecticides appliedon a calendar schedule for vector control are noteffective in preventing disease. The insecticidesare costly, toxic to farm workers, and disruptiveto integrated pest management programs. Wedetermined the separate and combined effects ofa reduced-risk insecticide (spinosad), a systemicacquired resistance inducer (Actigard), and UV-reflective metalized mulch on control of tomatospotted wilt virus. The metalized mulch was mosteffective in reducing disease incidence. Actigardsignificantly reduced incidence of tomato spottedwilt virus on the standard black mulch but notmetalized mulch. Spinosad was as effective asmethamidophos in reducing the spread of thedisease during mid- and late-season. Theregimen of metalized mulch, Actigard, andinsecticides reduced tomato spotted wilt virusby as much as 76%.

INTRODUCTIONTomato spotted wilt virus (TSWV) is the

type species of the genus Tospovirus in the familyBunyaviridae. Over the past two decades,increased outbreaks of TSWV occurred in a vastnumber of crops. The disease was originallydescribed in Australia (Brittlebank 1919), with itsetiology recognized by Samuel et al. (1930). Overthe past ten years, eleven additional tospovirusspecies have been described. These differ inserology, genome sequence, vector specificity, and

natural host range. Thrips and TSWV are stillconsidered new, emerging problems onagricultural crops in the southern US, eventhough growers in Georgia and northern Floridaidentified thrips and TSWV as their most seriousinsect and disease problems in a recent survey(Bauske et al. 1998). The growers furtherrevealed that they apply on average 12.3 and 16.4insecticides per season in Georgia and Florida,respectively. The conventional insecticideprogram for thrips consists of broad-spectruminsecticides (namely methamidophos). No singlecontrol measure has been reported as effective inreducing the TSWV incidence.

Tomato spotted wilt symptoms on tomatovary greatly, young leaves usually developnumerous small dark spots. Growing tips maydieback and streaks appear on terminal stems.Early infections cause severe stunting and severereductions of fruit production. Infected plantsafter fruit-set produce fruit with chlorotic ornecrotic ring spots. Green fruit with such spotswill ripen with yellow blotches or spots. Themost frequently affected plants in the southeasternUnited States are tomato, peanut, tobacco andpepper. TSWV is known to infect over 1,000plant species in 80 botanical families.

Eight species in two genera, Frankliniellaand Thrips, are reported to transmit TSWV(Mound 1996, Webb et al. 1998). In Florida, thetwo main vectors are the western flower thrips(Frankliniella occidentalis) and the tobaccothrips (F. fusca). TSWV replicates in thripsvectors, thus the insect not only spreads the virus,but serves as a virus host. The virus is acquiredby the larvae but not by the adults, and the adultscan spread the virus to healthy host plants. Theadults that successfully acquire the virus as larvaeare responsible for transmission and spread. Theadults persistently transmit TSWV and theircontrol with insecticides does not preventsuccessful transmission due to the short timeof feeding necessary for infection to occur(Nagata 1999).

Individual growers in the southern UStypically have responded to the threat of TSWVby applying broad-spectrum insecticides on a

5

calendar basis (e.g, Bauske et al. 1998). Thisapproach is costly, highly toxic to farm workers,and extremely disruptive to IPM programs, andresearch consistently has revealed that losses tosolanaceous crops in the southern US fromTSWV typically is the result of primary infectionwhich can not be prevented by insecticide use(e.g., Puche et al. 1995, McPherson et al. 1995,1997). The reason is that the disease is transmit-ted to the plant before thrips are killed by insecti-cides. However, control of larval thrips feedingon infected plants can prevent secondary spreadthat would occur when these thrips develop toadult. Few insecticides are efficacious againstthrips and some of these are carbamate andorganophosphate insecticides that may not beavailable in the near future due to the FoodQuality Protection Act.

Because insecticides do not prevent adultthrips that acquire disease from infected plantsoutside a tomato field from transmitting diseaseafter migrating into the field, we have beeninvestigating other management tactics. HighlyUV-reflective aluminum (metalized) mulch iseffective in reducing primary infections ofTSWV. We showed during five years of research(1996-2000) that using metalized mulch reducesthrips populations and subsequent virus incidenceabout one half to two thirds in replicated fieldexperiments (J. Funderburk, S. Olson, J. Staviskyand T. Momol, unpublished data). Better resultswere obtained in commercial tomato fields duringthe springs of 1999 and 2000.

Plants can activate protective mechanismsupon detection of invading pathogens. Protectionexpressed locally at the site of primaryinoculation and also systemically in tissuesremote from the initial treatment is known assystemic acquired resistance (SAR) (Sticher et al.1997). Benzothiadiazole (Actigard, Novartis) hasbeen registered commercially in some countriesas an inducer of systemic acquired resistanceagainst a broad range of pathogens (Gorlach et al.1996). The SAR inducer benzothiadiazole hasbeen effective in reducing incidence of TSWV ontobacco, especially in combination withinsecticide imidacloprid (Csinos, Pappu, and

McPherson unpublished). This tactic is effectivein reducing both primary and secondary spreadof TSWV.

No single management tactic is highlyeffective in reducing losses from thrips andTSWV. Resistant varieties offer the best promisefor reducing losses from TSWV, but an integratedapproach will still be necessary to reduce damagefrom thrips and to prevent development of TSWVstrains able to infect resistant tomato cultivars(as happened in Hawaii).

The objective of this study was todetermine the separate and combined effects ofreduced-risk insecticides, a systemic acquiredresistance inducer, and metalized mulches onprimary and secondary spread of tomato spottedwilt virus in tomato.

MATERIALS AND METHODSA randomized complete block experiment

with four replications was conducted in the springof 2000. Same experiment was conducted in2001 with 6 replicates. The tomato crop wasproduced using typical commercial practices. Asplit-split-plot treatment arrangement was used todetermine the separate and combined effects ofeach tactic on efficacy to reduce TSWVincidence. Tomato cultivar was ‘FL 47’.Six-week-old transplants were spaced every 50cm in raised beds covered with plastic mulch.Plants were irrigated based on plant needsthrough a trickle tube placed at the center of eachbed. Treatment arrangement was a split-split plotwith mulch type the whole plot treatments,Actigard/no Actigard as the split plot treatments(16 replicates) and insecticide treatments(4 replicates) the split-split plot. Mulch type wasselected as the whole plot because the mulch typecan affect thrips on adjacent rows. Interplotinterference was detected in the experimentconducted in 1999, therefore the whole plots in2000 were separated by a 2 m buffer zone. Thestandard mulch type was black and the other typewas metalized mulch. The Actigard treatment wasa regimen of applications: 2 g [AI]/4000 plantswashed in 1 week prior to transplanting and 26.25g [AI]/ha four foliar sprays applied every fifteen

6

days after transplanting. Insecticide treatmentsfor thrips were untreated, spinosad (0.07 kg[AI]/ha), and methamidophos (0.4 kg [AI]/ha) and acombination of spinosad with methamidophos.These were applied weekly for six weeks fromlate April to early June.

Plot size for each split-split plot was 4 rowsby 11 m. Parameters evaluated included %infected plants (tomato spotted wilt incidence),thrips per flower, and fruit yield and quality.Incidence of TSWV in each plot was determinedby % plants with visible symptoms weekly orbi-weekly from May 2nd to June 21st.Symptomatic plants were tested for eachsampling date by ELISA (Agdia, Elkhart, IN) inorder to confirm a diagnosis of TSWV. Thripswere sampled 2 and 6 days after each weeklyapplication of insecticides. On each sample date,ten flowers from each sub-subplot were placed in70% alcohol and carried to the laboratory. Thripsadults were extracted and identified to speciesunder a 40X dissecting microscope, and thripslarvae were quantified.

RESULTS AND DISCUSSIONIn the spring of 2000, North Florida

experienced a severe epidemic of TSWV ontomatoes. In 2001 tomato spotted wilt incidenceswere not high. In this experiment infectionsoccurred naturally. Thrips common in the tomatoflowers both years were F. occidentalis, F. triticiand F. bispinosa. Incidence of F. occidentalis in2000 is shown in Figure 1.

The overall incidence of TSWV wassignificantly lower in metalized mulch plots thanthe black mulch plots (Table 1 and Fig. 2).Applications of Actigard did not decrease diseaseincidence in metalized mulch treatments.Actigard was effective in reducing diseaseincidence on black mulch.

Numbers of larval thrips per flower weredecreased by each insecticide treatment (Fig. 3),which reduced the amount of secondary diseaseincidence that occurred primarily in mid- to late-season. The regimen of metalized mulch,Actigard, and insecticides reduced TSWVcompared to incidence on untreated black mulchby as much as 76%.

Our research has demonstrated thatmetalized mulch is an effective tactic to reducethrips populations and resulting infection byTSWV. This tactic serves to reduce both primaryand secondary infection. Secondary infection canoccur if thrips larvae are not controlled byinsecticides. Methamidophos is efficaciousagainst thrips, and spinosad is a safer, biologicalinsecticide with efficacy against F. occidentalisadults and larvae. Actigard needs furtherevaluation, but shows promise as a managementtactic against TSWV.

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ACKNOWLEDGEMENTS

We thank Julie Stavisky, Paula Bernsen, JackieSnell, and Hank Dankers for technical assistance.

LITERATURE CITED

Bauske, E. M., G. M. Zehnder, E. J. Sikora, and J.Kemble. 1998. Southeastern tomato growersadopt integrated pest management.HortTechnology 8:40-44.

Brittlebank, C. C. 1919. Tomato diseases.J. Agric. Victoria 27:213-235.

Gorlach, J., S. Volrath, G. Knauf-Beither, G.Hengy, U. Beckhove, K.-H. Kogel, M.Oostendorp, T. Staub, E. Ward, H. Kessman,and R. Ryals. 1996. Benzothiadiazole, anovel class of inducers of systemic acquiredresistance, activates gene expression anddisease resistance in wheat.The Plant Cell 8:629-643.

McPherson, R. M., R. J. Beshear, and A. K.Culbreath. 1992. Seasonal abundance ofthrips (Thysanoptera: Suborders Terebrantiaand Tubulifera) in Georgia flue-cured tobaccoand impact of management practices on theincidence of tomato spotted wilt virus.J. Entomol. Sci. 27:257-268.

McPherson, R. M., A. K. Culbreath, M. G.Stephenson, and D. C. Jones. 1995. Impact oftransplant date and insecticide controlpractices on the incidence of tomato spottedwilt virus and insect pests of flue-curedtobacco. Tobacco Sci. 39:30-37.

Mound, L. A. 1996. The Thysanoptera vectorspecies of Tospovirus.Acta Hort. 431:298-307.

Nagata, T. 1999. Competence and specificity ofthrips in the transmission of tomato spottedwilt virus. Thesis Wageningen, 96pp.

Puche, H., R. D. Berger, and J. E. Funderburk.1995. Population dynamics of Frankliniellathrips and progress of tomato spotted wiltvirus. Crop Protection 14:577-583.

Samuel, G., J. G. Bald, and H. A. Pitman. 1930.Investigations on ‘spotted wilt’ of tomatoes.Commonwealth of Australia, Council Sci.Ind. Res. Bull. 44:64.

Sticher, L., B. Mauch-Mani, and J. P. Metraux.1997. Systemic acquired esistance.Annu. Rev. Phytopathology 35:235-270.

Webb, S., J. Tsai, and F. Mitchell. 1998. Bionom-ics of Frankliniella bispinosa and its trans-mission of tomato spotted wilt virus. In: TheFourth International Symposium onTospovirus and Thrips in Floral andVegetable Crops. Wageningen,The Netherlands, pp. 67-68.

8

Figure 1. Mean number of F. occidentalis in tomato flowers in April and May 2000.

0

2

4

6

0

2

4

6

0

2

4

6

0

2

4

6

Black Mulch; ActigardBlack Mulch; no ActigardUV (Metalized) Mulch; ActigardUV (Metalized) Mulch; no Actigard

29 Apr 5 May 11 May 17 May 23 May 29 May

Spring 2000 Tomato29 Apr 5 May 11 May 17 May 23 May 29 May

F. o

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enta

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ower

untreated methamidophos

/methamidophos spinosadspinosad

9

Table 1. Effect of mulch type, Actigard and insecticides on the incidence of TSWV in tomato(Spring 2000).

z Insecticide, UTC = Untreated control, Mon = Monitor (methamidophos),Spin = Spin Tor (Spinosad), Mon+Spin (Monitor and Spin Tor weekly alternated).y % Incidence is average of 4 replicatesx % Incidence is average of 16 replicates

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5.22

7.91noM 4.11 2.61

nipS 1.71 1.42

nipS+noM 9.61 0.61

0

1

2

3

4

Black-NA Black-AT Met - NA Met- AT

10

Figure 2. Effect of mulch type (Black vs. Metalized), Actigard (AT) and no-Actigard (NA)on the incidence of TSWV in tomato (Spring 2001, as of June 5).

% TSWV Incidence

11

Figure 3. Mean number of larval thrips in tomato flowers in April and May 2000.

0

1

2

0

1

20

1

2

0

1

2

Black Mulch; ActigardBlack Mulch; no ActigardUV (Metalized) Mulch; ActigardUV (Metalized) Mulch; no Actigard


Spring 2000 Tomato

untreated methamidophos

/methamidophos spinosadspinosad


larv

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12

Residual Effects of FumigantAlternatives on Nutsedge, RootknotNematode, and Fusarium Wilt of FallTomato and Double CroppedCucumber / Cover Crop ProductionFall 2000 - Spring 2001

James P. Gilreath, Joseph W. Noling,John P. Jones and Phyllis R. Gilreath

AbstractResults of the first three years of a five year

study indicate that mixtures of Telone andchloropicrin (Telone C-17 or C-35), combinedwith Tillam herbicide, are as effective as mixturesof methyl bromide with chloropicrin (67/33formulation) for control of nutsedge, rootknot andother nematodes, and fusarium wilt (race 3) intomato and double cropped cucumber. Tomatoand cucumber production was similar with TeloneC-17 and methyl bromide. Soil solarization usingclear plastic mulch to heat the soil for 8 weekswas intermediate in its efficacy; that is, itgenerally was better than applying no fumigantbut was not as effective as methyl bromide orTelone C-17 plus Tillam. Solarization appeared tofavor rootknot nematode development, but theincreased incidence compared to the nontreatedcontrol was due to a lack of root system for thecontrol plants due to crop loss as a result offusarium wilt. Resurgence of nematodes was aproblem with all treatments, including methylbromide, and rootknot nematodes were quiteplentiful on double cropped cucumber as a result.Thus far, the spring cropping systems have nothad that much of an effect on the fall tomato cropwith the exception that stubby root nematode wasreduced following millet as a spring cover cropand there appeared to be a trend for doublecropped cucumbers to increase the rootknotnematode population in fall tomato. Completionof the next two years of this study should

determine whether or not there is any truth to thetheory that alternative fumigant efficacy willdecline with time as residual effects of previousmethyl bromide use diminish.

Since 1993 research has been conducted atthe Gulf Coast Research and Education Center toidentify alternatives to methyl bromide and theirstrengths and weaknesses. Additionally, we havestrived to find ways to improve efficacy withvarious alternatives, whether it be throughimprovements in application technology orselection of combinations of materials toovercome inherent weaknesses in one product.Recognizing the potential impact of theimpending loss of methyl bromide as a soilfumigant and the concern that growers have aboutthe long term effects of adopting alternativepractices, a multi-year study was initiated in thefall of 1998 to determine the efficacy of achemical and a nonchemical alternative forsoilborne pest control in fall tomato and springcropping systems. This study has been funded bythe Florida Tomato Committee, the USDA - ARS,FFVA and Dow AgroSciences and is the onlystudy of its kind in the world.

This long term study compares the currentchemical replacement for methyl bromide,Telone C-17, and the best nonchemicalalternative, soil solarization, to methyl bromidefor broadspectrum soilborne pest control in falltomato. It also examines the effects of thesefall-applied alternatives on spring double-croppedcucumber and millet grown as a cover crop. Inaddition to the effects of the alternatives onspring cropping practices, the study alsoinvestigates the residual effects of the springcropping practices (double cropped cucumber,millet and weed fallow) on the soilborne pestsand crop for tomato the following fall.Telone C-17 (35 gal/acre) in the bed has beencombined with Tillam herbicide (4 lb.a.i./acre)applied broadcast prior to bed formation for thefirst two years and during the third year (fall

13

2000) Devrinol (2 lb.a.i./acre) was tank mixedwith Tillam to improve pigweed and crabgrasscontrol. Soil solarization was conducted bycovering beds with clear plastic mulch for 8weeks then painting the mulch film white prior toplanting tomato. In the summer of 2000,solarization was modified by broadcastincorporating Devrinol herbicide (2 lb.a.i./acre)prior to bed formation in an attempt to improveoverall weed control. Methyl bromide /chloropicrin mixture (67/33 @ 350 lb/acre) wasapplied to the bed in the same fashion as TeloneC-17 using 3 chisels per bed. A nontreated controlwas included to allow monitoring of pestpopulations and determination of actual controlof individual soilborne pests. This study is nowbeginning its fourth year.

The study was designed to answer manyquestions but the most important probably waswhat happens over time when we continually usethese alternatives and the effect of previousmethyl bromide use is diminished. Over the firstthree years of fumigation for fall tomato followedby spring double cropping, millet cover crop orfallow practices we have seen large fluctuationsin nutsedge and nematode populations but a morestable incidence level of Fusarium wilt, race 3,which has averaged about 95% in the nontreatedcontrols since the second year of this study. Weobserved reductions in the populations ofnematodes this past year as a result of moisturestress in the crop. The prolonged drought made itdifficult to maintain good soil moisture in thebed. Weed populations were less affected bythe drought as weeds are more efficientscavengers of moisture in the bed where thenutsedge resided.

Tomato plant vigor early in the seasonduring the third fall crop season was not affectedthat much by treatment, other than the reductionin vigor where no fumigant or alternative is used,but by midseason plant vigor was greatly reducedwith solarization and plants in the nontreated

controls were almost dead due to the ravages ofintense nematode, nutsedge and Fusarium wiltpressure (Table 1). The least amount of root gallformation due to rootknot nematodes wasobserved on plants which grew in soil treatedwith Telone C-17. The most occurred with soilsolarization.

Weed control was a mixed bag (Table 2).Both alternative treatments controlled nutsedgeand piweed as well as methyl bromide,statistically speaking; although from a numericalperspective the Telone C-17 treatment did notappear that good. Soil solarization had anadvantage in that the nutsedge was allowed toemerge through the mulch then was burned offwith Gramoxone Extra prior to transplantingtomatoes. The soil heating promoted more of thetubers to germinate early so that the Gramoxoneweakened them and few nongerminated tubersremained to replace them. Also, it is believed thatDevrinol aided nutsedge control, even though it isnot normally considered particularly effectiveagainst nutsedge. Pigweed has been observed tobe a weed problem with Tillam on some farms,but it was not in this study. Results of growerherbicide trials help explain this and will bediscussed later in this report. Crabgrass continuedto be a problem with solarization, even afterincluding Devrinol this past fall in order to givesolarization some help with weed control. Oneexplanation for this may be the degradation ofDevrinol over time and the heating of the soil dueto the opacity of the clear mulch after paintingprior to transplanting tomatoes. Remember thatDevrinol was already in the soil for 2 monthsprior to planting, thus we were nearing the end ofits effective life in the soil before we even beganthe crop. The grass which did appear did not doso until about midseason, after what wouldnormally be considered the life expectancy ofresidual activity from Devrinol. Telone C-17 +Tillam + Devrinol was applied later in thesummer, closer to planting, and thus was able to

14

maintain weed control farther into the crop season.Unfortunately, nematode population levels

were not as great as they had been during 1999,but there were still enough to have an effect andto be able to discern differences among treatments.There were few rootknot nematodes in the soilaround the tomato roots where no fumigant wasused because there were few live roots to supportthem as most of the plants had been killed byFusarium wilt (Tables 3 and 5). The mostrootknot nematodes were found associated withroots grown in soil solarization plots. Bothalternatives reduced the populations of stunt andsting nematodes, but no treatment impactedstubby root nematodes. We saw little effect of thespring cropping practice on the pest levels or cropresponse in fall tomatoes, with the exception ofpopulations of nematodes (Table 4). Spring milletreduced the number of stubby root nematodesrecovered from soil around tomato roots in thefollowing fall compared to double croppedcucumbers or allowing the land to lay fallow.There appeared to be more rootknot nematodes inthe fall following spring double cropping, but thiswas not a statistically significant difference.

Fusarium wilt race 3 infected 94% of thenontreated control plants during the fall of 2000(Tables 5 and 6). The incidence of fusarium wiltwas very low with methyl bromide and Telone C-17 (3 and 7%, respectively), whereas 57% of theplants growing in solarized soil were infected.Bacterial wilt and southern blight were minorpests in this study and there was no difference intheir incidences. Interestingly, unlike rootknotnematodes, there was no effect of spring croppingpractice on fusarium wilt of tomato in the follow-ing fall. This demonstrates that the spring “crops”do not serve as hosts for this pest.

The most important thing in tomatoproduction is what you put in the bucket and howit grades out. Fruit were harvested twice duringthe season and were sorted into cull andmarketable categories by hand, then were size

graded using a portable mechanical grader. Thesorting criteria were based on what two growersindicated would be allowed during fall 2000 so asto assure our criteria reflected not only the USDAgrade standards, but also the local interpretationof those standards. Telone C-17 + Tillam +Devrinol produced as many tomatoes as methylbromide in each of the three size categories andtotal marketable (Table 7). Production wasreduced with soil solarization + Devrinolcompared to methyl bromide or Telone C-17 withsolarization falling between no fumigation andmethyl bromide.

Double cropping is an important part oftomato production for many growers as itprovides certain economies to the farmingoperation. Growers have questioned the futureof double cropping in the absence of methylbromide. This long term study also addressesthat issue.

Cucumber was grown as a double crop thefollowing spring for each of the 3 years of thisstudy. Cucumber plant vigor, vine length (as ameasure of growth) and yield were reduced withsolarization and in the nontreated control,compared to methyl bromide (Table 8). TeloneC-17 + herbicide performed as well as methylbromide for these parameters. Weed controlduring the double crop was not different amongthe alternative treatments with both Telone C-17+ Tillam + Devrinol and solarization + Devrinolperforming as well as methyl bromide for allweed species, except crabgrass where, onceagain, there was more crabgrass with solarizationthan with anything else (Table 9). There was aresurgence of rootknot nematodes with alltreatments, but the levels were lower than in thefall for soil solarization, presumably due to lackof sufficient host plant material. There was nodifference in rootknot nematode populationsamong the treatments, but methyl bromide andthe two alternatives reduced the numbers of ring,cyst, and sting nematodes present in the soil

15

around the cucumber roots.The implications of the results of this

project are that Telone C-17 (or Telone C-35)combined with the appropriate herbicide can beas effective as methyl bromide against soilbornepests of tomato and can maintain that level ofcontrol in the absence of methyl bromide.However, the application of herbicide partnerswill require greater attention to detail andselection of proper application procedures andequipment. Nematode control with Teloneproducts can be as good as with methyl bromide.Telone C-17 can control Fusarium wilt as well asmethyl bromide / chloropicrin mixtures when itis applied in the bed using the same equipmentas methyl bromide.

16

Table 1. Effect of methyl bromide alternative on vigor of tomato plants and the extent of gallformation on fall tomato roots as a result of infestation with rootknot nematodes in the longterm cropping system study. Year 3. Fall 2000.

z Treatment means within columns followed by the same letter are not significantly different at the 5%level of significance as determined by Duncan’s new multiple range test.

Nontreated

Methyl bromine (67/33)

Telone C-17 +Tillam +Devrinol

Solarization (8 wks.) +Devrinol

Plant vigor (%)

56 bz

79 a

79 a

79 a

16 c

80 a

79 a

52 b

Root Galling Index(0 to 10 scale)

Early season Midseason

4.4 a

1.9 b

0.4 c

5.0 a

Alternative

17

Table 2. Effect of methyl bromide alternative on weed control in fall tomato in the long termcropping system study. Year 3. Fall 2000.


Nontreated




Number of weeds per 70 ft of row

585 az

6 b

77 b

37 b

22 a

1 b

1 b

1 b

Nutsedge Pigweed CrabgrassMidseason Late season

Nutsedge Pigweed Crabgrass

3 ab

1 b

1 b

7 a

620 a

29 b

114 b

52 b

18 a

0 b

0 b

1 b

4 a

0 b

1 b

7 a

Alternative

18

Table 3. Effect of methyl bromide alternative on nematodes in the rhizosphere of fall tomato plants inthe long term cropping system study. Year 3. Fall 2000.


Nontreated




Number of nematodes per 100 cc of soil

43 bz

4 b

4 b

481 a

37 a

1 b

4 b

12 b

Rootknot Stunt Stubby Ring Cyst Sting Lance Awl Total

7 a

0 b

0 b

1 a

2 a

0 b

0 b

0 b

9 a

0 b

0 b

1 b

166 b

46 b

46 b

524 a

Alternative

24 a

40 a

38 a

24 a

43 a

1 b

1 b

6 b

1 a

1 a

0 a

0 a

19

Table 4. Effect of spring cropping practices on nematodes in the rhizosphere of fall tomato plants inthe long term cropping system study. Year 3. Fall 2000.


Double croppedcucumber

Millet

Fallow


234 az

88 a

78 a

11 a

15 a

14 a

Rootknot Stunt Stubby Ring Cyst Sting Lance Awl Total

3 a

2 a

1 a

1 a

1 a

0 a

0 a

1 a

6 a

298 a

142 a

148 a

CroppingPractice

37 a

22 b

35 a

11 a

14 a

13 a

1 a

0 a

1 a

20

Table 5. Effect of methyl bromide alternative on incidence of soilborne diseases of fall tomatoplants in the long term cropping system study. Year 3. Fall 2000.


Nontreated




Percentage of plants affected

1 az

0 a

1 a

1 a

94 a

3 c

7 c

57 b

Southern blight Fusarium wilt race 3 Dopple Bacterial wilt

0 a

1 a

1 a

0 a

Alternative

1 a

1 a

1 a

0 a

21

Table 6. Effect of spring cropping practices on incidence of soilborne diseases of fall tomatoplants in the long term cropping system study. Year 3. Fall 2000.


Percentage of plants affected

1 az

1 a

1 a

40 a

40 a

40 a

Southern blight Fusarium wilt race 3 Dopple Bacterial wilt

0 a

1 a

1 a

1 a

1 a

1 a

Double croppedcucumber

Millet

Fallow

CroppingPractice

22

Table 7. Effect of methyl bromide alternative on seasonal total yield of fresh market fall tomatoplants in the long term cropping system study. Year 3. Fall 2000.


Nontreated




Weight (kg) of fruit per 10 plants (20 ft of row) per plot

4.3 cz

27.4 a

25.2 a

13.6 b

1.5 c

7.7 a

7.6 a

4.1 b

5 x 6 6 x 6 6 x 7 Marketable Cull

3.7 b

6.5 a

6.1 a

7.5 a

Alternative

10.2 c

49.2 a

45.8 a

25.4 b

4.4 b

14.1 a

13.1 a

7.6 b

23

Table 8. Effect of fall fumigant treatments on vigor, height and fruit production of spring double-cropped, trellised cucumber plants in the third year of the long term cropping system study.10 April 2001.

z Treatment means followed by the same letter are not significantly different at the 5% level of signifi-cance as determined by Duncan’s new multiple range test.Height is an average of 10 plants per plot from the center row of each plot.

Nontreated

Methyl bromine(67/33)

Telone C-17TillamDevrinol

SolarizationDevrinol

0

350 lbs.

35 gal4 lbs.a.i.2 lbs.a.i.

8 wks.2 lbs.a.i

30 bz

85 a

74 a

40 b

FallTreatment

36 b

153 a

122 a

69 b

70.7 a

81.0 a

76.2 a

42.0 b

Rateper acre

Vigor(%)

Height(cm)

Lbs. of fruitper 20 ft of row

24

Table 9. Effect of fall fumigant treatments on weed control and nematode populations in the rhizosphere ofspring double-cropped, cucumber plants in the third year of the long term cropping system study.21 may 2001.

z Treatment means followed by the same letter are not significantly different at the 5% level of significance asdetermined by Duncan’s new multiple range test.

Nontreated

Methylbromine(67/33)

Telone C-17TillamDevrinol

SolarizationDevrinol

0

350 lbs.

35 gal4 lbs.a.i.2 lbs.a.i.

8 wks.2 lbs.a.i

117 a

0 b

0 b

7 b

FallTreatment

56 a

1 b

3 b

19 b

62 a

0 a

0 a

7 b

Rateper acre


Rootknot Stunt Stubby Ring Cyst Sting

Number of weeds per 70 ft of rowNutsedge Grass Pigweed

1501 az

59 b

489 b

112 b

2 b

1 b

2 b

28 a

51 a

0 b

0 b

2 b

40 a

59 a

82 a

156 a

32 a

1 b

14 ab

11 ab

38 a

46 a

41 a

39 a

25

Development of Diagnostic Testfor Identification of Tomato Little-Leaf

S.M. Olson (Horticultural Science),P.C. Andersen (Horticultural Sciences) andT.M. Momol (Plant Pathologist)University of Florida, IFAS NFREC30 Research RoadQuincy, FL 32351

P.D. Roberts (Plant Pathologist)University of Florida, IFAS SWFREC2686 SR 29 NImmokalle, FL 34142

E. Rosskopf (Soil Microbiologist)USDA-ARSUS Horticultural Research Laboratory2001 South Rock RoadFort Pierce, FL 34945

ABSTRACTTomato plants affected by little-leaf

produce very little marketable yield. While thenorth Florida area has reduced the problem byvery careful water management with dripirrigation systems, south Florida is not able toachieve this as easily due to the seep systems andvery level fields that are hard to drain after heavyrains. This problem seems to be on the increase insouth Florida from the reports from growers,scouting companies and samples submitted to thePlant Problem Clinics. Early diagnosis isnecessary to provide the grower with theinformation he needs to correct the problem.At this time there is not a diagnostic test toidentify little-leaf and we hope through aminoacid analysis we can develop a test.

JUSTIFICATIONThe problem first presented itself in the fall

of 1986 when several growers in the northFlorida production area encountered plants intheir fields with unusual growth characteristics.Early symptoms consisted of interveinal chlorosisin the young leaves with veins remaining darkgreen. Subsequently top growth became severelydistorted with leaflets along the midrib failing toexpand properly, resulting in a “little-leaf” appearance. Additional symptoms includedcessation of terminal growth, leaflets with twistedand brittle midribs and axillary buds with verylittle and distorted growth. The latter symptomscan be confused with cucumber mosaic virus.Fruit that set when plants are mildly affected aredistorted with fruit being flattened and at timesradial cracks extending from the calyx to theblossom scar. There is almost no seed set inaffected fruit and all fruit are unmarketable. Inthe more severely affected plants, blooms aredistorted and fail to set any fruit. Several growerscommented that the same set of symptoms hadbeen observed in the past, but only on a very fewplants. Following 1986, the set of symptoms wasreferred to as “tomato little-leaf”. Since 1986 theproblem has been observed sporadically in thefall crops in the north Florida area. Occasionallythe problem has affected large areas and causedsignificant yield reduction (as much as 80%). Ithas only occurred in a single spring crop (1992)when little leaf occurred throughout the northFlorida/south Georgia production area. It has alsooccurred in the East Coast tomato production areain the fall/winter season of 1998 and 1999, wereyield losses from 20 to 50% occurred. It has beenoccurring with much greater frequency in theSouth Florida production area in the last threeseasons. It has also been reported in NorthCarolina, Ohio, Texas, Maryland, Poland, Italyand possibly Indonesia.

26

Attempts to Determine the EtiologyIn the beginning the problem was thought

to be a virus, numerous samples were sent to theExtension Plant Diagnostic Clinic in Gainesvillefor virus detection and all samples were negative.Some growers believed the problem to benutritional, since from a distance early symptomsemulated iron deficiency. Extensive tissuesampling and analysis were performed fromaffected and non-affected plants. The resultsfailed to reveal an abnormal nutritional situation.Extensive testing of soil and plant tissue forherbicide residues were also negative. Onecommon observation was that affected plantsshowed up in the wetter areas of the fields.Finally, cuttings made from distorted topsdeveloped normal growth habits after rootingshowing that the problem was not virus related.

Possible ExplanationIn tobacco there exists a nonparasitic

disease called frenching. It is considered to be anonparasitic disease because the organism ororganisms that cause the disease do not livewithin the tissues of the plant. Early symptoms offrenching consist of chlorosis along the marginsof young leaves. The chlorosis gradually spreadstoward the midrib until all interveinal regions areinvolved. The veins remain dark green. As theleaf continues to develop, only the midribelongates producing a long, ribbon-like leaf.Terminal growth is greatly retarded and apicaldominance is lost, resulting in a stunted plantwith an increased number of small brittle leaves.The foliar symptoms on tobacco are nearlyidentical to the symptoms observed in tomatolittle leaf. Tomatoes were mentioned to besensitive to the problem in the literature over 60years ago but symptoms were never described.Other plants have also been reported to besusceptible, these include petunia, eggplant,ragweed, sorrel (Oxalis stricta) and squash.Chrysanthemums are also susceptible and the

disorder is referred to as yellow strapleaf and wasa problem of serious economic consequence tochrysanthemum growers in Florida between 1956and 1965.

The etiology of the conditions describedabove are not completely understood. The currenthypothesis is that one or more amino acid analogsare synthesized by certain soil microorganismsand released into the rhizoshpere. Thesecompounds, which are structurally similar to theamino acid leucine, are taken up by the plantcausing morphological changes and stunting insusceptible plants at very low concentrations. Itis believed that these compounds act as anantimetabolite of the amino acid leucine.Currently in tobacco, three soil microorganismshave been implicated as possible causal agents.The first organism implicated was the bacteriumBacillus cereus. This organism is found in allsoils. In controlled experiments, symptoms offrenching were obtained from diffusion of acompound produce by B. cereus into smalltobacco plants. B. cereus is a ubiquitous soilinhabitant and has been observed in largenumbers in the root zone of tobacco plants withfrenching symptoms. Another organism that hasbeen implicated is the fungus Aspergillus wentii.This organism has been shown to produce acompound (ANCPA) which is a potent antagonistof leucine. In the lab it has been shown thatANCPA in minute quantities can producesymptoms on tobacco similar to frenching andcan similarly affect the growth of other cropssuch as bean, tomato, sunflower andchrysanthemum. Inoculations of tobacco rootsystems with the soilborne fungus Macrophominaphaseolina has also resulted in the appearance offrenching symptoms. It should be noted however,that often times symptoms fail to develop afterinoculation with these organisms. Somepreliminary work in tomatoes in north Floridahas showed that the xylem fluid of affected plantscontained much higher levels (two fold) of free

27

amino acids especially the sulfur containing onesthan unaffected plants.

Role of Environmental Conditions inSymptom Development

The problem has been shown to be moresevere with warm soil temperatures. In tobaccosymptoms can appear in 8 to 15 days with soiltemperatures of 95oF, but rarely appear in soiltemperatures of 70oF or less. Symptoms aremore severe on neutral or alkaline soils and arerarely observed with a soil pH of 6.3 or less.Frenching of tobacco and yellow strapleaf ofchrysanthemum are more prevalent on wet,poorly-aerated soils.It is apparent the for the problem to occur a fairlyunique combination of the above soil conditionsmust occur in combination with an appropriatesoil microorganism.

Possible Control MethodsIn tobacco control measures can include,

reduction of soil pH to about 6.3 or less or use ofammonium sulfate as the nitrogen source to lowerthe pH around the root system. In chrysanthemumproduction to reduce the potential of the problem,it is advised that soil moisture be maintained soas not to cause water-logged conditions. In bothtobacco and chrysanthemum, pulling the affectedplants up and replanting has resulted in the plantsgrowing out of the disease. This remission ofsymptoms is apparently the result of improvedaeration and perhaps by root pruning whichresulted in decreased uptake of toxins by the rootsystem. In recent years in north Florida we haveseen very little of the problem because growershave become aware of the need to monitor soilmoisture very carefully and make surewaterlogged conditions do not occur. Lackingdefinitive information, we cannot suggest anyradical changes in tomato culture at this time foravoidance of the disorder other than monitoringsoil moisture levels to avoid waterlogged

conditions. Higher soil pH has been implicated intobacco but not chrysanthemum. Changes in soilpH for tomato should be approached carefully toavoid problems that might accompany reducedlime utilization. The problem usually has notcarried over from one season to the next, but atleast one grower on the east coast area hasabandoned a production field because little leafhas showed up two years in a row. If little-leafcan be diagnosed early enough, drying a field outwill usually result in subsequence growth to benormal and plants will set normal fruit. Thesingle most important factor to reduce thepossibility of little-leaf occurring is to monitorsoil moisture and prevent water logging conditions.

OBJECTIVESThe objective of this study is to develop a

diagnostic test for little leaf in tomato. There isnot a diagnostic test in place for frenching intobacco but symptoms are unique and diagnosisis made by visual symptoms. In tomatoes littleleaf can mimic several virus diseases, especiallycucumber mosaic virus which is showing upmore frequently in the state. Since we have notbeen able to cause the symptoms to occur in agreenhouse even with soil from affected areas wemust collect samples from growers fields.Samples will be collected from both affected andunaffected plants. Samples will consist of bothxylem fluid (must be taken during dark) andterminal growth tips. Both will be analyzed forfree and bound amino acids. The GC columnsused will also be able to separate the variousisomers of the amino acids. Through the resultsof the analyses we hope to develop a diagnostictest for little-leaf.

28

PROGRESS TO DATEPlant tissue, xylem fluid and soil samples

were obtained from little-leaf symptomatic plantsat two locations. The first location was inOkeechobee, FL where 11 symptomatic plantsand 10 asymptomatic plants were sampled. Allsymptomatic plant samples showed seversymptoms of little-leaf. The second location, inSanford, FL, had plants that displayed varyingdegrees of little-leaf symptoms. Plants were ratedseverity of symptoms to see if a correlation willexist between severity and amounts and types ofamino acids found. Samples have been frozen atminus 80 degrees until analysis can beaccomplished. GC column has been foundand purchased that can analyze the samples.

29

DEVELOPING TOMATOCULTIVARS WITHBROAD-SPECTRUMRESISTANCE TOWHITEFLY-TRANSMITTEDGEMINIVIRUSES IN FLORIDA

J. E. Polston1, J. W. Scott1, E. Hiebert2 andD. J. Schuster1

University of Florida1 Gulf Coast Research & Education Center5007 60th St. EastBradenton, FL2 Dept. of Plant PathologyGainesville, FL

ABSTRACTImmunity to TYLCV was demonstrated in

inbred lines of tomato (Fla. 7613 and Fla. 7634)through the use of genetic engineering. Five outof eight transgenes tested produced resistantplants however, one transgene (2/5 TYLCV Rep),was superior to all others. Resistant plants had anormal phenotype, showed no symptoms ofinfection, and no virus could be detected ininoculated plants by two sensitive laboratoryassays. TYLCV could not be introduced intoresistant plants through the grafting of susceptibleinfected plants, nor could it be detected insusceptible plants grafted onto inoculated resistantplants. Resistance is therefore characterized asimmunity since no virus could be detected afterinoculation by the most sensitive methodsavailable. This Immunity was demonstrated in thefield as well as in the greenhouse, by usingwhiteflies to inoculate TYLCV to seedlingtomato plants. Immunity was successfully carriedthrough 3 generations of tomato and was demon-strated in tobacco, another plant susceptible toTYLCV. This is the best resistance to TYLCV everdocumented and is the only known example ofimmunity to TYLCV. The development of thisimmunity is a big step forward in the developmentof cultivars with superior resistance to whitefly-transmitted geminiviruses.

T1 Generation EvaluationWe completed the evaluation of T

1

generation tomatoes transformed with one ofeight different constructs containing the TYLCVRep gene, modified Rep genes, a TYLCV C4gene or a modified C4 gene, some inserted in thesense direction and some in the oppositedirection.We evaluated the T

1 progeny of 154 T

0

generation plants each transformed with one ofthe constructs (Table 1). We inoculated approxi-mately 15 T

1 generation progeny plants obtained

from the seed of each of the 154 T0 plants using

whiteflies reared on TYLCV-infected tomatoplants. We usually achieved 100% inoculation ofthe susceptible controls. We found resistance toTYLCV in five of the eight constructs, althoughone construct, a truncated Rep gene (designatedas 2/5 TYLCV Rep), out performed all others andthe progeny of several plants were selected forevaluation in the T

2 and T

3 generations (Table 2,

3). All resistant plants in the T1 generation

showed no symptoms, had normal phenotypes,and no TYLCV was detected using two sensitivelaboratory assays (PCR and hybridization).

T2 Generation EvaluationT

2 generation progeny from selected T

1

generation plants transformed with the 2/5TYLCV Rep transgene were inoculated for 3weeks at the 4 true-leaf stage in the greenhouseand were evaluated for resistance in the field inthe fall 2000 and spring 2001 seasons.Approximately 45 plants from each T

1 parent

plant were evaluated. Susceptible controls were100% infected 4 weeks after transplanting to thefield. Resistance was stably transferred to the T

2

generation. As expected, the T2 progeny were

segregating for resistance, and the frequencies ofresistance were high and showed very strongresistance (Table 2). The phenotype of allresistant plants was normal, and yield on manyplants looked unaffected by TYLCV. Thisresistance appears to be superior to that derivedfrom wild Lycopersicon species due to theabsence of virus in resistant plants, and thepresence of a normal plant phenotype. Resistantplants, though inoculated at a very young and

30

susceptible stage, appeared to be immune toinfection by TYLCV. This 2/5 TYLCV Repconstruct generated resistance to TYLCV that ismore robust than commercially availableresistance, and is commercially desirable anduseful. Patent protection of this construct isbeing pursued.

T3 Generation EvaluationT

3 generation plants transformed with the

2/5 TYLCV Rep transgene were screened forresistance in the field in the spring 2001 season.We planted 45 plants from 10 T

2 generation

plants. T3 plants were inoculated with TYLCV in

the greenhouse before transplant to the field.Results are shown in Table 3. Plants were stillsegregating for immunity, but in general, rates ofimmunity were higher than in the previousgeneration, indicating that we are successfullyselecting for plants with immunity. Thesefrequencies suggest that the immunity is adominantly rather than recessively inherited trait.Within one to two more generations we will beable to obtain plants where the immunity occursin 100% of the plants due to the presence of asingle transgene.

Transformation of AdditionalTomato Inbreds

Attempts were made to transform Fla. 7777and Fla. 7722, two inbred lines that are theparents of the hybrid Fla. 7722 (described in J.W.Scott’s proposal) with the 2/5 TYLCV Repconstruct. We were able to transform both lineswith the transgene, and obtained 23 T

0 generation

plants of Fla 7777 and 12 T0 generation plants of

line Fla. 7722. These plants will be treated asline Fla 7613, so that within a few generations wewill have resistant plants with single copies of thetransgene, suitable for use as hybrid parents.

Transformation of TobaccoIn addition to the work in tomato, the

2/5 TYLCV Rep construct was transformed intotobacco, another host of TYLCV, and immunityto infection by TYLCV was observed in tobacco.This is a further confirmation that the 2/5

TYLCV Rep transgene is able to confer immunityto TYLCV.

Characterization of the Resistance asImmunity

Inoculated but resistant T2 and T

3 plants in

the field showed no evidence of the presence ofvirus beginning 4 weeks after inoculation throughthe season until harvest. Plants were tested at 4,8 and 12 weeks after transplanting to the fieldusing both nucleic acid spot hybridization andPCR. Plants never showed any symptoms ofinfection by TYLCV. Grafting experimentsshowed that there was no virus present ininoculated but resistant plants, and that viruscould not be induced by grafting an infectedsusceptible plant onto a resistant non-inoculatedplant. These tests indicate that the transgene, 2/5TYLCV Rep, prevents the establishment ofinfection and that these plants are immuneto infection by TYLCV. This is the first exampleof immunity to TYLCV ever documented and thisis a big step forward in the development ofcultivars with superior resistance to whitefly-transmitted geminiviruses.

Analysis of ResistanceStudies have just begun to identify the

resistance mechanism conferred by the 2/5 Repconstruct, the relationship between the number ofcopies of the transformed gene required togenerate immunity, and the breadth of resistancethis gene may have against other tomatogeminiviruses and different isolates of TYLCV.

Future EndevoursWe will continue to evaluate and select

plants for immunity and single copies of the 2/5TYLCV Rep transgene in order to obtain plantssuitable as hybrid parents. We also plan tocombine this resistance with ToMoV resistanceobtained in a previous study.

31

Table 1. Results of evaluation of T1 generation plants transformed with one of eight constructs

for resistance to TYLCV.

tcurtsnoC

Tfo.oN0

noitareneGstnalPdeniatbO

Tfo.oN1

noitareneGstnalP

detaulavE

gnomAegnaR.qerFehtfoynegorP

otecnatsiseRfoVCLYT

Tfo.oN1

stneraP.neGdleiFrofdetceleS

noitaulavE

VCLYT5/2peR

87 504 %19-%9 T41morf(620

)stnerap

2TiC 52 692 %55-%015

T2morf(0

)stnerap

2T1C1C 41 561 %68-%73

T2morf(0

)stnerap

4C 2 42 0 0

4C 81 002 %02-%7 0

1CN 9 011 02T2morf(

0)stnerap

1CN 6 97 %52-%62T1morf(

0)tnerap

1C 2 82 0 0

LATOT 451 703,1

Table 2. Results of evaluation of selected T0,

T1,

and T

2 generation plants transformed with the

2/5 TYLCV Rep transgene.

TTTTT00000noitareneG noitareneG noitareneG noitareneG noitareneG

tnalP tnalP tnalP tnalP tnalP

–esuohneerG –esuohneerG –esuohneerG –esuohneerG –esuohneerGTTTTT11111

noitareneG noitareneG noitareneG noitareneG noitareneGTTTTT22222

noitareneG noitareneG noitareneG noitareneG noitareneG1002gnirpS,0002llaF:dleiF 1002gnirpS,0002llaF:dleiF 1002gnirpS,0002llaF:dleiF 1002gnirpS,0002llaF:dleiF 1002gnirpS,0002llaF:dleiF

htiwstnalP% htiwstnalP% htiwstnalP% htiwstnalP% htiwstnalP%ytinummI ytinummI ytinummI ytinummI ytinummI 11111

TTTTT11111tneraP tneraP tneraP tneraP tneraP

.oN.dI .oN.dI .oN.dI .oN.dI .oN.dIhtiwstnalP% htiwstnalP% htiwstnalP% htiwstnalP% htiwstnalP%

ytinummI ytinummI ytinummI ytinummI ytinummI

2 03 5-2 57

9-2 36

12 19 20-12 14

40-12 97

80-12 96

01-12 93

32 02 20-32 72

50-32 24

70-32 23

52 02 40-52 75

23 60-23 04

21-23 44

73 37 60-73 24

11-73 87

21-73 24

31-73 25

167.alF)enegsnarton(

0 3167.alF 0

33

Table 3. Results of evaluation of T

3 generation plants transformed

with the 2/5 TYLCV Rep gene in the field, Spring 2001.

.oN.dItnalP .oN.dItnalP .oN.dItnalP .oN.dItnalP .oN.dItnalPstnalP.oNlatoT stnalP.oNlatoT stnalP.oNlatoT stnalP.oNlatoT stnalP.oNlatoT

detaulavE detaulavE detaulavE detaulavE detaulavEhtiwstnalPfo% htiwstnalPfo% htiwstnalPfo% htiwstnalPfo% htiwstnalPfo%

VCLYTotytinummI VCLYTotytinummI VCLYTotytinummI VCLYTotytinummI VCLYTotytinummI

62-9-2 82 %57

64-9-2 34 %07

22-8-12 44 %08

34-8-12 44 %68

8-2-32 24 %06

62-5-32 13 %48

44-4-52 72 %65

22-11-52 24 %54

53-51-52 34 %94

1-31-73 83 %78

3167.alFdemrofsnarttoN

04 %0

34

BREEDING TOMATOES FORRESISTANCE TO ALL THREE RACESOF THE BACTERIAL SPOT PATHOGEN

J. W. ScottGulf Coast Research & Education CenterUniversity of Florida5007 60th Street EastBradenton, FL 34203

J. B. JonesPlant Pathology DepartmentUniversity of FloridaGainesville, FL 23611

INTRODUCTIONBacterial spot is still the most ubiquitous diseaseproblem of tomatoes in Florida. Three tomatoraces of Xanthomonas campestris pv. vesicatoria(Xcv), causal agent of bacterial spot, have beendiscovered to date (Jones et al., 1995). InFlorida, there are two races, the original race (T1)and the race discovered in 1991 is (T3) (Jones etal., 1995). Race T2 was originally reported fromBrazil, but has now been isolated in some statesin the USA including Ohio. Our breeding projectbegan in 1983 when we found Hawaii 7998 wasresistant to race T1 (Jones and Scott, 1986).More recently resistance to race T3 was discov-ered in several accessions including Hawaii 7981(Scott et al., 1995), and this resistance has beenincorporated into advanced T1 resistant breedinglines. We found PI 114490 was resistant to raceT2 in the summers of 1995 and 1996 (Scott et al.,1997) and this was further verified from 1997through 2000 at Wooster, Ohio. PI 114490 alsowas resistant to race T1 and tolerant to race T3.The general T2 resistance from PI 114490 needsto be incorporated into advanced breeding lines.This general resistance could be important shouldrace T2 migrate into Florida. The use of varietieswith such resistance might also protect againstany new race which might emerge in the future.The objectives of this research were:

1) To develop breeding lines resistant toT1 and T3

2) To incorporate general Xcv resistancefrom PI 114490 into advancedbreeding lines.

3) To discover other sources ofresistance to races T1, T2, and T3

OBJECTIVE 1Methods

In summer 2000, 247 breeding lines (F2

and more inbred) and 41 hybrids with resistancewere inoculated with race T3 and evaluated in thefield. Some of the hybrids were evaluated forcommercial potential and some were made torecombine traits from two resistant parents. Inspring 2001, 10 F

1’s with some resistance to races

T1 and T3 were evaluated. Additionally, 150inbreds were evaluated for horticultural type inthe spring. A small number of hybrids heterozy-gous for bacterial spot resistance were evaluatedin advanced observational trials at GCREC andNFREC. Three resistant inbreds were evaluatedin a replicated trial at GCREC in Spring 2001.At Homestead (TREC), 25 lines with bacterialspot resistance were evaluated in winter 2001.In summer 2001, 290 breeding lines (F

2 and

beyond) are being evaluated that have T1 and T3resistance. Also this summer 77 F

1’s are being

evaluated. Seven inbreds are being evaluated in areplicated trial this summer. Four of theseinbreds were selected in the Homestead trial.

ResultsIn summer 2000, 61 selections were made

for lines with race T1 and T3 resistance and 36lines were selected with only T3 resistance. Therewere 78 selections with T1 and T3 resistancecombined with resistance from PI 114490. Inspring 2001, 22 selections were made and 11 F

1’s

were advanced to the F2 generation. At

Homestead, 31 selections were made with T1and T3 resistance. Many resistant inbreds aretoo small fruited. However, Fla. 8000 had goodyields and fruit quality with adequate fruit size inthe Spring 2001 replicated trial. Hybrids with thisline will be evaluated this summer. Five hybrids

35

using other parents looked good in Spring 2001and these will be tested further. Any hybridsshowing potential will be widely tested in 2002 inUniversity and grower trials with a release madeas soon as feasible if results are good.

OBJECTIVE 2Methods

In summer 2000, 115 breeding lines withresistance from PI 114490 were evaluated inBradenton. In spring 2001, 68 inbreds and 41hybrids with resistance from PI 114490 wereevaluated. In summer 2000, an experiment wasconducted testing 20 lines for resistance to racesT1 and T2 in Ohio, and T3 in Bradenton. Diseaseseverity was rated at all locations using the ratingscale of Horsfall and Barratt, (1945). AtBradenton, another experiment was conductedusing 2 resistant parents, 2 heterozygous resistantF

1’s

, and susceptible parents that were inoculated

with and without an avirulent T3 strain ofbacterial spot. A similar experiment was done inFremont, Ohio where the field was also inoculatedwith T1. The Ohio experiment failed and will notbe reported.

ResultsThere were 68 selections made in summer

2000. In spring 2000, 41 hybrids were advancedto the F

2 generation. In general, we have found

that resistance from PI 114490 is very effectivefor races T1 and T2 and less effective for T3.One related series of lines tested for all 3 raceshad good resistance to all of them however andthis material has been emphasized in crosses.In Spring 2001, three hybrids showed considerablepromise using this pollen source. Otherwise,resistant lines from PI 114490 are being crossedwith T3 resistant lines from Hawaiian resistancesources to insure adequate resistance to race T3.The avirulent T3 treatments had no effect on T3infection. Homozygous resistant inbreds weresignificantly more resistant than the heterozygoushybrids, which were significantly more resistantthan the susceptible lines. These results areconsistent with previous results.

OBJECTIVE 3Methods

All 144 L. pimpinellifolium accessionswere screened for resistance to race T2 usingconfluent necrosis hypersensitivity tests and leafdip tests. No hypersensitivity was found, butresistance was found in LA 1682 and LA 1684.Crosses were made between these two accessionsand LA 442 and PI 114490, respectively. The leafdip test was used on F

2’s from these crosses and

selections were made for improved resistance.Seed from these selections have been planted inSummer 2001 and they will be tested forresistance to T3 in the field. Next year they willbe tested for T1 and T2 in the field in Ohio.

LITERATURE CITED

Horsfall, J.G. and R.W. Barratt. 1945.An improved system for measuring plantdisease. Phytopathology 36:655. (Abstr.).

Jones, J.B. and J.W. Scott. 1986.Hypersensitive response in tomato toXanthomonas campestris pv. vesicatoria.Plant Dis. 70:337-339.

Jones, J.B., R.E. Stall, J.W. Scott, G.C. Somodi,H. Bouzar, and N.C. Hodge. 1995. A thirdtomato race of Xanthomonas campestris pv.vesicatoria. Plant Dis. 79:395-398.

Scott, J.W., J.B. Jones, G.C. Somodi, and R.E.Stall. 1995. Screening tomato accessions forresistance to Xanthomonas campestris pv.vesicatoria, race T3. HortScience 30:579-581.

Scott, J. W., S. A. Miller, R. E. Stall, J. B. Jones,G. C. Somodi, V. Barbosa, D. L . Francis, andF. Sahin. 1997. Resistance to Race T2 of thebacterial spot pathogen in tomato.HortScience 32(4):724-727.

36

BREEDING TOMATOESFOR FLORIDA

J. W. ScottGulf Coast Research & Education CenterUniversity of Florida5007 60th Street EastBradenton, Fl 34203

INTRODUCTIONImproved varieties are needed to keep the

Florida tomato industry competitive in achanging world. Improvements include the areasof yield, pest resistance, and fruit quality.Florida’s geography offers many challenges fortomato improvement, since high temperatureslimit fruit set and are conducive to disease andinsect problems. There are no neighboring stateswith similar latitudes to most of Florida, so thereis less help in solving agricultural problems thanis the case in many states. Although privatecompanies have tomato breeding programs thatdevelop varieties for Florida, these companies arenot set up to handle many of the long term, highrisk projects that could prove valuable in thefuture. The University of Florida tomato breedingprogram works on such projects and works inpartnership with the private companies to deliverimproved varieties of benefit to the Floridatomato industry. Much of the groundwork forthe development of heat-tolerant varieties wasdone at the University of Florida (Scott et al.,1986). ‘Solar Set’ has been an importantcommercial, heat-tolerant variety for 11 yearsafter it’s release (Scott et al., 1989). We now haveFusarium wilt race 3 resistant varieties using aresistance gene discovered in a wild species bythis program in the 1980’s (Scott and Jones,1989). Breeding lines with Fusarium crown androot rot resistance have recently been released(Scott and Jones, 2000) and varieties ought to beavailable in a few years. With the impending lossof methyl bromide these pathogens could becomemore widespread. Other diseases such as bacterialwilt and spotted wilt occur in Florida, but cause

far more damage in other regions of the world. Ifsomething changes and these diseases becomemore prevalent, Florida would benefit fromresistant varieties. Geminiviruses like tomatomottle (ToMoV) and tomato yellow leaf curlvirus (TYLCV) pose a threat to Florida tomatoproduction. Other regions have these or othergeminivruses (Polston and Anderson,1997). Aproject has been ongoing since 1990 utilizingresistance genes from a wild species. It appearsthat four genes have been introgressed, and thesegenes may well be useful in solving the long termgeminivirus problems that Florida will likelyface. Tomatoes have met with considerabledissatisfaction in the marketplace. Essentially,this relates to compromises that are made inproviding fruit that will ship well. Solutions tothis problem are not simple. Research is neededto provide tomatoes that will be more acceptableto consumers. On the bright side, recent medicalliterature has shown that lycopene, the redpigment in tomato, has strong antioxidantproperties that reduce several cancers. Work inthe breeding program has been ongoing for 18years with a crimson gene (ogc) that improvesinternal tomato color and increases lycopene by50%. Crimson varieties could be a boon to theFlorida industry in the not too distant future.Genetic alteration of plant architecture mightprovide varieties for mechanical harvest orreduced costs in manual labor and equipment.This could be critical for future production inFlorida. This is another long-term, high riskproject that is being pursued in my program thatis not likely to be attempted by the private sector.Funding of the Florida Tomato Committee hasbeen imperative to the operation of this breedingprogram, an investment that has and will continueto pay dividends.

Objectives of this project were:

1) To develop varieties or breedinglines resistant to fungal pathogens(e.g. Fusarium wilt race 3 andFusarium crown rot).

2) To develop improved breeding linesor varieties resistant to bacterial wilt.

37

3) To develop improvedheat-tolerant inbreds and hybrids.

4) To improve fruit quality andpostharvest characteristics.

5) To develop commerciallyacceptable breeding linesresistant to ToMoV and TYLCVusing resistance from L. chilense.

OBJECTIVE 1Methods

There were 53, 114, and 31 lines screenedfor Fusarium wilt race 3 in fall 2000, spring 2001,and summer 2001, respectively. Twenty-two F

1’s

were evaluated for the first time. There were 34,51, and 14 lines screened for Fusarium crown rotin fall 2000, spring 2001, and summer 2001,respectively. In spring 2001, a yield trialcomparing advanced inbreds was conducted thatincluded three lines resistant to race 3. Severalhybrids with resistance to race 3 or crown rotwere evaluated in observation trials in fall 2000and spring 2001. Race 3 resistant hybrids werealso tested in state-wide replicated trials andgrower trials.

ResultsFla. 7946, a Fusarium wilt race 3 resistant

inbred, has continued to perform well as it did theprevious year. It was crossed with NC 84173 tomake hybrid Fla. 7973. This hybrid could be an“improved ‘Floralina’” since Fla. 7946 fruit arelarger, smoother and have less blossom-end rotthan Fla. 7547, the race 3 resistant parent in‘Floralina’. Fla. 7973 did perform better than‘Floralina’ at GCREC in Spring 2001. It also didwell in a grower trial. If other trials show similarresults, Fla. 7973 may be released as a ‘Floralina’replacement. There has been considerable testingof Fla. 7862, a hybrid resistant to both race 3 andcrown rot, and with the crimson gene. Thishybrid could be released as a high lycopenevariety. In spring 2001, a promising new crownrot resistant crimson inbred emerged. It resultedfrom the cross of Fla. 7781 (Scott and Jones,2000) and a NC State inbred. Hybrids using thisline will be made in Fall 2001 and testing will bedone next year.

OBJECTIVE 2Methods

There were 54 and 91 lines inoculated withthe bacterial wilt pathogen and evaluated in springand summer 2001, respectively. Crosses weremade in fall 2000 and 28 hybrids with a bacterialwilt resistant parent were grown in spring 2001.In summer 2001, eight inbreds and control linesare in a replicated trial that has been inoculatedwith the bacterial wilt pathogen.

ResultsThere were 20 F

1’s advanced to F

2 in the

spring and 15 selections made from the bacterialwilt resistant breeding lines. It has been difficultto obtain large-fruited lines with resistancecomparable to the resistance of small-fruitedsource lines like Hawaii 7997. Most of theselections were from lines that had been crossedto Hawaii 7997 again to recover greaterresistance. However, Fla. 7979 is an inbred withheat-tolerance that has not been crossed againwith Hawaii 7997. It is in the Summer 2001replicated trial, and if it shows improvement over‘Neptune’, it will be released. Previous trials ongrower fields infested with bacterial wiltindicated that hybrids with ‘Neptune’ had about67% survival while susceptible varieties hadabout 10% survival. This or an improved level ofresistance might be commercially acceptable ifcombined with treatments that might assist withprotection such as use of MessingerR orbacteriophages. Early observation of thereplicated trial indicates that none of the linesare as resistant as Hawaii 7997.

OBJECTIVE 3Methods

Heat-tolerant (HT) fruit setting ability isbeing incorporated into all phases of the breedingprogram. In spring 2001, 91 HT inbreds wereevaluated for their performance under non-heatstress conditions. In summer 2001, 112 HT linesare being evaluated under high temperatureconditions. Numerous crosses with HT recurrentparents were made in fall 2000 and spring 2001.

38

evaluated. In spring 2001, 40 UF lines, 2 UFF

1’s, and 13 rin lines were evaluated. Another

aspect of fruit quality is the development of highlycopene varieties by using the crimson (ogc)gene. This gene is widely distributed in thevarious breeding projects. New hybrids arecontinually being made and evaluated. Anotherproject is to develop tomatoes that do not requirestaking by use of the brachytic (br) gene thatreduces plant height and increases side shoots.These tomatoes are called compact growth habit(CGH) tomatoes. Many are very firm. In fall2000, 64 CGH lines were evaluated. There were47 CGH lines evaluated in spring 2001 and 74new hybrids made. In winter 2001, 60 CGH lineswere evaluated in Homestead at TREC.

ResultsIt has been difficult to obtain UF lines with

good flavor characteristics, although this is beingemphasized. Many lines tend to have somewhatbland flavor. Some UF lines do have some goodhorticultural characteristics if consistently goodflavor can be obtained. Flavor is also emphasizedin the rin project since rin/+ hybrids often havepoor taste. Some UF and rin/+ lines have betterflavor, but it is not known if the flavor will beconsistently good without further testing. Ahybrid with ogc (Fla. 7862) was mentioned underObjective 1. More testing will be done with thisand other crimson hybrids. After considerabletrials over many seasons, it appears that crimsonlines often have good flavor, but are not high inacidity. This can result in a somewhat blandflavor under some conditions. Recent work hasemphasized crimson lines with greater acidity toovercome this problem. Twenty-two crosses weremade in fall 2000 to improve ogc acidity.Improvement has been made in the CGH linesand some may soon reach commercial potential.Emphasis is being placed on jointless lines thatcould result in machine harvest varieties but theseare not as advanced horticulturally. Seed of somejointed pedicel inbreds are ready for advancedtesting on grower farms as a prototype todetermine problems that may be encounteredwith a ground tomato production system usingCGH plant architecture.

In the yield trial mentioned under Objective 1,five of the lines tested were experimental HTlines. In summer 2000, a yield trial was conductedto evaluate HT inbreds and hybrids. NumerousHT hybrids were tested in fall and springreplicated or observation trials. Seven HT linesare being tested in the same replicated trialmentioned under the bacterial spot project forsummer 2001.

ResultsSeveral HT hybrids have performed well in

state-wide trials, one being Fla. 7885. Fla. 7885has two parents with HT, Fla. 7776 and Fla.7906B. To date commercially available HThybrids have one HT parent. Fla. 7885 is a weekearlier than other HT hybrids during fall seasons.Inbred Fla. 7949B is closely related to Fla.7906B, but it has looked better. We aresubstituting it for Fla. 7906B in the above crossand the hybrid Fla. 7885B will be compared toFla. 7885. One of these could be released as ahybrid with HT superior to varieties presentlyavailable. Jointless hybrid NC 99405 also yieldedwell in the summer 1999 and summer 2000 trialsand looked good in fall 2000 and spring 2001trials. This is a hybrid that was made by Dr.Randy Gardner at North Carolina StateUniversity between one of his inbreds crossedwith Fla. 7771, a HT, jointless, breeding linerelease made in 1999 (Scott, 2000). Release ofthis hybrid would provide growers with a jointlesspedicel variety that, for the first time, couldcompete with HT, jointed varieties under hightemperature conditions. Seed is being tested ongrower farms via the Harris-Moran Seed Company.

OBJECTIVE 4MethodsFruit quality and shelf-life are emphasized in allbreeding projects. One method to improveshelf-life is to develop varieties with a high levelof firmness that we call ultrafirmness. Anothermethod is to incorporate the ripening inhibitor(rin) gene in firm genetic backgrounds and makeheterozygous rin hybrids. In fall 2000, 25ultrafirm (UF) inbreds and two hybrids were

39

OBJECTIVE 5Methods

There were 347 lines inoculated separatelywith ToMoV and TYLCV, rated for diseaseseverity and evaluated for horticultural type inboth fall 2000 and spring 2001. There were 29and 161 hybrids with a ToMoV resistant parentthat were evaluated in fall 2000 and spring 2001,respectively. Some of the most resistant lines withbetter horticultural characteristics were tested inreplicated trials that were inoculated separatelywith ToMoV and TYLCV in spring 2001. Thesetrials allow for statistical comparisons of the lineswhich helps to determine the best resistancesources. Some of the more resistant lines werealso sent to cooperators around the world todetermine their resistance to other geminivirusesincluding TYLCV. This included a trial inGuatemala where six ToMoV resistant lines werecompared to lines bred elsewhere in the world forTYLCV resistance. Although not specified in thegrant proposal, 28 and 40 inbreds with spottedwilt resistance were evaluated in fall 2000 andspring 2001, respectively. There were 6 spottedwilt resistant hybrids evaluated in the spring atBradenton. Four F

1’s were tested on a grower

farm in Quincy. Eight hybrids and 9 inbreds(using a different resistance source) wereevaluated in an experiment in Quincy. Selectionfor resistance is done with sequence characterizedamplified region (SCAR) molecular markers thateliminate the need to screen with thrips andpotentially spread the virus in the west coastgrowing region.

ResultsThere were 344 geminivirus resistant

selections made in the fall. In spring 2001, 189selections were made and 140 F

1’s were ad-

vanced. Most lines now have determinate planthabits with normal leaf size and good fruit set.Progress is still needed in overall yield, fruit sizeand some other characteristics. The ToMoV andTYLCV replicated trials and breeding plotsindicated that almost all of the lines resistant toToMoV were also resistant to TYLCV. Data fromthe world testing indicated that many of theToMoV resistant lines also had resistance to other

geminiviruses. In the Guatemala trial, there wasinfection by unknown bipartite geminviruses andthe ToMoV bred lines were more resistant thanany of the TYLCV bred lines from other breedingprograms. Thus, we may have potentially usefulgenes for a long term solution to geminviruses inFlorida. Next we hope to determine which genesare present in the existing lines and also synthesizeother lines to obtain lines with all possiblecombinations of resistance genes. These lines willthen be tested at various locations around theworld to determine the gene effects on the variousgeminiviruses. Results of this testing shouldallow for effective breeding strategies. This workrequires linked molecular markers that are beingdeveloped. Fla. 7964 has performed the best ofthe spotted wilt resistant hybrids being trialed. Itlooked good in North Carolina in summer 2000,in the grower trial in Quincy in spring 2001, andin the replicated spring 2001 trial at Bradenton. Itcontinues to be tested and it appears likely that itwill be released in the fall of 2001. Some spottedwilt resistant inbreds have shown improvementover existing lines and in some hybridcombinations. Spotted wilt resistance is importantto Tomato Committee members who grow inNorth Florida or elsewhere in the southeasternUS at present. It will also be important if thisdisease becomes more serious in the peninsulaof Florida where it has been of only minorimportance so far.

40

LITERATURE CITED

Polston, J. E. and P. K. Anderson. 1997. Theemergence of whitefly-transmittedgeminiviruses in tomato in the WesternHemisphere. Plant Dis. 81: 1358-1369.

Scott, J. W. 2000.Fla. 7771, a medium-large,heat-tolerant, jointless-pedicel tomato.HortScience 34(5):968-969.

Scott, J. W., and J. P. Jones. 1989. Monogenicresistance in tomato to Fusarium oxysporumf. sp. lycopersici race 3. Euphytica 40:49-53.

Scott, J. W., and John Paul Jones. 1995. Fla. 7547and Fla. 7481 tomato breeding lines resistantto Fusarium oxysporum f. sp. lycopersiciraces 1,2, and 3. HortScience 30(3):645-646.

Scott, J. W., and John Paul Jones. 2000. Fla. 7775and Fla. 7781: Tomato breeding linesresistant to Fusarium crown and root rot.HortScience 35(6):1183-1184.

Scott, J. W., S. M. Olson, J. J. Bryan, T. K. Howe,P. J. Stoffella, and J. A. Bartz. 1989. SolarSet: A heat tolerant, fresh market tomatohybrid. Fla. Agric. Expt. Sta. Circ. S-359 10p.

Scott, J. W., R. B. Volin, H. H. Bryan, and S. M.Olson. 1986. Use of hybrids to develop heattolerant tomato cultivars.Proc. Fla. State Hort. Soc. 99:311-314.

41

CONTINUATION OF TOMATO FLAVORRESEARCH FOR HIGH LYCOPENE,HYBRIDS AND INBREDS AS WELL ASOTHER TOMATO LINES WITHSPECIFIC FLAVORCHARACTERISTICS

Elizabeth A. BaldwinUSDA/ARS Citrus &Subtropical Products LaboratoryWinter Haven, FL

J.W. ScottUniversity of Florida Gulf Coast Research &Education CenterBradenton, FL

INTRODUCTIONWe have looked at different genetic lines

containing the crimson gene, the crimson genecrossed with rin, a transgenic line that shouldresult in increased sugars, and other lines selectedfor a range of flavor quality attributes over theyears for the effect of genetic changes on tomatoaroma compounds (Baldwin et al., 2000). Fromthis range in flavor quality we can learn moreabout what components in relative proportionsare desirable for good tomato flavor. Eventuallywe hope to provide tomato breeders andmolecular biologists with chemical and molecularmarkers for selection targets in breedingprograms. Currently, tomato breeders interestedin selecting lines for flavor quality have littleinformation to guide them.

In this study, We continued to look at highlycopene cultivars (the crimson gene ogc and ogc

x rin). High lycopene tomatoes may garnerhealth benefits due to the anti-oxidant, anti-canceractivity of lycopene (Nguyen and Schwartz,1999). Furthermore, lycopene breakdownproducts, such as ß-ionone, are important flavorcompounds and the high color makes for

attractive fruit. This means that high lycopenecultivars may result in better flavored, betterlooking tomatoes (Buttery and Ling, 1993;Buttery et al., 1999), and may compensate for thelower color and aroma associated with rin hybrids(Baldwin et al., 1991, Baldwin et al., 2000).

METHODSTomato (Lycopersicon esculentum Mill.)

cultivars were grown in a completely randomizedblock design with three blocks and ten plants perplot at the University of Florida Gulf CoastResearch and Education Center in Bradenton infall and spring of 2000 and 2001, respectively.Cultivars, were sampled in the field from threeblocks, and informally evaluated for flavor by thebreeder and one technician. From this screening,cultivars were selected for sensory andinstrumental/chemical analysis to represent arange in flavor for normal tomatoes, fixed forspecific flavor notes, and for comparison to thecrimson gene, a crimson - rin hybrid.

Tomatoes from the fall 2000 crop wereharvested, driven to Winter Haven where theywere ripened for 2 days at 20°C, pureed so thateach sample represented at least 5 fruit percultivar, and served to a trained descriptive panelof at least 8 panelists; or tomato wedgesrepresenting at least 5 fruit were served to a panelof 36 consumers on site at Bradenton, the day ofharvest. Fruit from the same harvest were analyzedfor solids, sugars, acids and aroma compounds byrefractometer, HPLC, titration, and gaschromatography (GC) (Baldwin et al., 1998).

Tomatoes were analyzed by an experiencedpanel of 30-36 panelists who sampled tomatowedges representing at least 5 fruit per cultivar.Sub samples were taken 3 times during the panelsession and analyzed for color and flavorcomponents as described above. Color analyseswere done on tomato homogenate using aMinolta chromameter and a scanningspectrophotometer at 450-650 nm which is therange of absorption spectra for lycopene.

42

RESULTSTomatoes from the fall 2000 (Table 1)

showed cultivar 343 (sweet) as rated highest insweetness followed by ‘Solar Set’ (340) while therin/crimson hybrid was rated lowest (342). Theacid line (319) was rated highest in sournessfollowed by Florida 47 (344) and ‘Solar Set’(340), while two crimson lines ( 319 and 342)were lowest. For overall flavor ‘Solar Set’ (340)and the sweet line (343) were highest and therin/crimson hybrid (342) was lowest.

Trained panel data revealed that there weresignificant differences for green vine aroma with334 (FL47) and 343 (selected for sweet) beinghigh, and 341 (FL7945/crimson) and 344 (FL47)low (P=0.15); green aroma with 319 (acidcrimson line) and 344 (FL47) high and 342(rin/crimson hybrid) low (P=0.13); tomatoripening aroma with 319 (acid crimson line), 341(crimson hybrid), and 344 (Fl47) high and 342(rin/crimson hybrid) low (P=0.18); floral aroma,with 319 (acid crimson), 339 (release possibility),

Table 1. Cultivars evaluated in fall 2000

and 341 (crimson hybrid) being high and 343(sweet line) and 344 (FL47) low (P=0.09);tomato ripening taste with 339 (releasepossibility) and 341 (crimson) high and 342(rin/crimson hybrid) low (P=0.11); and citrustaste with 319 (crimson acid) and 343 (sweetline) high and 340 (‘Solar Set’), 341 (crimson),and 342 (rin/crimson hybrid) low (P=0.2).Fall volatile data for aldehydes and ketoneswas 50% that found for spring 2001 tomatoes(data not shown).

stnemmocredeerB,ravitluC ssenteewS ssenruoS rovalF

teewsdecnalab,312 CB2.4 A8.5 BA6.4

enetoracatled,dica,322 C6.3 A9.5 BA9.3

gev,larolf,ytiurf,822 A2.5 D5.3 A9.4

'teSraloS',642 BA8.4 C2.4 A8.4

74LF,742 CB2.4 CB5.4 A8.4

,842 nir dirbyhnosmirc/ BA8.4 D5.3 BA7.4

esaelerelbissop,152 BA6.4 B0.5 A9.4

43

The breeder assessment of the spring 2001genetic material for flavor was confirmed by theconsumer panel analysis (Table 1) for spring2001 fruit where the 228 (fruity/floral), 246(‘Solar Set’), and the 248 (rin/crimson hybrid)were rated sweetest while the 223 (high acid) wasrated lowest for sweetness and highest forsourness. Cultivar 228 (fruity/floral) was ratedlowest for sourness along with the 248(rin/ crimson hybrid), while 228 (fruity/floral)and 251 (possible release) were rated highest foroverall flavor, although only significantlydifferent from 223 (the acid line).

Table 2. Cultivars evaluated spring 2000

The trained panel looked at the same lines(Fig 1) with the addition of 201 and 205 whichthe breeder assessed as bland and bitter,respectively. Cultivar 246 (‘Solar Set’) got thehighest intensity rating for overall, vine, earth,and musty aroma, of which vine was significantat P=0.18. The two lines evaluated by the breederas balanced/sweet and fruity floral (213 and 228,respectively) were highest in floral aroma which

was significant at P=0.2. The trained panel foundcultivars 228 (fruity/floral), 246 (‘Solar Set’), and248 (rin/crimson hybrid) to be highest in sweetnessand 223 (acid line) lowest, significant at P=0.008.Conversely, 228 (fruity/floral) was lowest insourness rating and 223 (acid line) was highest.The fruity/floral line (228) was highest in tropicaltaste and lowest in citrus taste while the acidcultivar (223) was high in citrus (P=0.11).

stnemmocredeerB,ravitluC ssenteewS ssenruoS rovalF

teewsdecnalab,312 CB2.4 A8.5 BA6.4

enetoracatled,dica,322 C6.3 A9.5 BA9.3

gev,larolf,ytiurf,822 A2.5 D5.3 A9.4

'teSraloS',642 BA8.4 C2.4 A8.4

74LF,742 CB2.4 CB5.4 A8.4

,842 nir dirbyhnosmirc/ BA8.4 D5.3 BA7.4

esaelerelbissop,152 BA6.4 B0.5 A9.4

44

These results were confirmed by chemicalanalyses in that 223 (acid line) and 228(fruity/floral) were high in aldehydes (Fig. 2A)and ketones (Fig. 2B). 228 (fruity/floral) washigh in geranylacetone and ß-ionone which arefruity volatiles; 213 (balanced tomato) was highin ß-ionone; and 223 (acid line), 247 (FL47), 248(rin/crimson hybrid), and 251(possible release)were also high in geranylacetone.

The fruity cultivar (228) was high inlycopene (Fig. 3A), which is perhaps why it hadthe fruity/floral note since lycopene breaks downinto ß-ionone and geranylacetone. The rin/crimsonhybrid had good color and volatile content aswell as the highest solids/acids ratio (Fig. 2B).This is promising for a tomato with the rin gene,since rin hybrids are notoriously low in volatiles(flavor), and color. Cultivars 228 (fruity/floral)and 248 (rin/crimson hybrid) were highest ratedby the trained panel for sweetness and had thehighest sucrose equivalents (Fig. 3C), but wereonly slightly high in solids (Fig. 3B). Solids arenot always a good indicator of sweetness.

In conclusion, it appears that asuccessful rin/crimson hybrid has been selected,a new release looks promising, and a fruity floralnote may be fixed in line 228. Several moreseasons of data are needed to confirm this.

Literature Cited

Baldwin, E. A., J.W. Scott, M.A. Einstein,T.M.M. Malundo, B.T. Carr, and R.L.Shewfelt, and K.S. Tandon. 1998.Relationship between sensory andinstrumental analysis for tomato flavor.J. Amer. Soc. Hort. Sci. 123: 906-915.

Baldwin, E.A., M.O. Nisperos-Carriedo, and J.W.Scott. 1992. Levels of flavor volatiles in anormal cultivar, ripening inhibitor and theirhybrid. Proc. Fla. State Hot. Soc. 104: 86-89.

Baldwin, E.A., M.O. Nisperos, and J.W. Scott.1991. Quantitative analysis of flavorparameters in six Florida tomato varieties(Lycopersicon esculentum Mill).J. Agric. Food Chem. 39:1135-1140.

Buttery, R.G. and L. Ling. 1993b. Volatilecomponents of tomato fruit and plant parts:Relationship and biogenesis, p. 22-34. In: R.Teranishi, R.G. Buttery, and H. Sugisawa(eds.). Bioactive Volatile Compounds fromPlants. Amer. Chem. Soc., Washington, DC.

Buttery , R.G., R. Teranishi, R.A. Flath, and L.C.Ling. 1989. Fresh tomato volatiles:Composition and Sensory Studies,p. 213-222. In: R. Teranishi, R.G. Buttery,and F. Shahidi, (eds.). Flavor Chemistry,Trends and Developments. AmericanChemical Society, Washington, DC.

Nguyen, M.L. and S.J. Schwartz. 1999.Lycopene: Chemical and biologicalproperties, Food Technol. 53(2):38-45.

45

Fig. 1. Trained descriptive sensory panel (6-8 panelists) data on spring 2001 cultivars (+ breedercomments): 201 (bland), 205 (bitter), 213 (balanced sweet), 223 (acid), 228 (fruity, floral), 246(‘Solar Set’), 247 (FL47), 248 (rin/crimson hybrid), and 251 (possible release) for descriptorsoverall aroma (ovr aroma), vine aroma (vine), green aroma (green), ripe tomato aroma (tom ripe),earthy aroma (earthy), sweet tomato aroma (tom sweet), musty aroma (musty), tropical aroma(tropical), floral aroma (floral), overall taste (ovr taste), sweet taste (sweet), sour taste (sour), ripetomato taste (tst tom ripe), tropical taste (tst tropical), fruit taste (tst fruity), citrus taste (citrus),bitter taste (bitter), and overall after taste (ovr after).

Trained panel

02468

10ovr aroma

vinegreen

tom ripe

earthy

tom sweet

mustytropical

Floralovr taste

sweetsour

tst tom ripe

tst tropical

tst fruity

citrusbitterovr after

201205213223228246247248251

46

Fig. 2. Chromameter ‘a’ values of homogenate (A), solids and acid data (B), and sugardata (C) for spring 2001cultivars: 201 (bland), 205 (bitter), 213 (balanced sweet), 223(acid), 228 (fruity, floral), 246 (‘Solar Set’), 247 (FL47), 248 (rin/crimson hybrid), and251 (possible release).

A B

C D

02468

10121416

Cultivar

AcetaldehydeHexanalcis-3-Hexenaltrans-2-Hexenaltrans-2-Heptenal

KETONES

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Cultivar

Acetone1-Penten-3-one6-Methyl-5-Heptan-2-oneGeranylacetoneß-Ionone

MISCELLANEOUS

0.000.010.010.020.020.030.030.040.040.050.05

Cultivar

2-Isobutylthiazole1-Nitro-2-Phenylethane2-Phenylethanol

ALCOHOLS

0.00

0.05

0.10

0.150.20

0.25

0.30

0.35

Cultivar

Methanol/100Ethanol/10Methylbutanolcis-3-HexenolLinalool

PP

M

PP

M

ALDEHYDES

E213

E223

E228

E246

E247

E248

E251

PP

M

PP

M

E213

E223

E228

E246

E247

E248

E251

E213

E223

E228

E246

E247

E248

E251

E213

E223

E228

E246

E247

E248

E251

47

Fig. 3. Volatile aldehydes (A), ketones (B), alcohols (C), andmiscellaneous (D) for spring 2001 cultivars: 201 (bland), 205(bitter), 213 (balanced sweet), 223 (acid), 228 (fruity, floral), 246 (‘Solar Set’), 247 (FL47), 248 (rin/crimson hybrid), and251 (possible release).

A

B

C

0.005.00

10.0015.0020.0025.0030.0035.00

201 205 213 223 228 246 247 248 251Cultivar

Lycopene'a' valueHue angle

Solids and Acids

0.00

5.00

10.00

15.00

20.00

201 205 213 223 228 246 247 248 251Cultivar

%TAx10BrixS.S./T.A.

Sugars

0.0

1.0

2.0

3.0

4.0

201 205 213 223 228 246 247 248 251Cultivar

GlucoseFructoseSugarsEquivalence

Color

% H

ue/m

g ly

cope

ne%

TA

or S

S or

TA

/SS

% s

ugar

s or

suc

rose

eq.

48

Development of grade standardsfor tomato softness

Dr. Elizabeth M. Lamb, Dr. Mark A. Ritenour,Dr. Peter J. Stoffella andDr. Steven A. Sargent1

Indian River Research andEducation Center (IRREC)2199 South Rock RoadFort Pierce, FL 34945(561) 468-3922FAX (561) 468-5668E-mail [email protected],[email protected], [email protected]

1Horticultural Sciences DepartmentP.O. Box 110690Gainesville, Fl 32611-0690(352) 392-1928FAX (352) 392-5653E-mail: [email protected]

AbstractAlthough fruit softness is used as an

indicator of tomato quality, no quantifiablemeasurement of softness is included in the USDAstandards. An evaluation of the methods andequipment available for measuring tomatosoftness resulted in the adaptation of existinglaboratory equipment for measuring fruitdeformation, based on standard force and timeperiod, for use as a portable, low cost tomatofirmness tester. Initial evaluations of repeatabilityof measurement and comparison to standardlaboratory measurements and subjectiveevaluation of tomato firmness suggest that theIRREC deformation tester has potential forproviding an accurate, objective measurement oftomato firmness. Evaluation of the equipment inassociation with state and USDA produceinspectors at destination markets is planned.

IntroductionTomato quality standards based on size,

color at harvest and damage/decay are specifiedin the Florida Tomato Committee’s GradeRequirements (Regulatory Bulletin No. 1, 1998-1999), based on the U.S. Standards for Grades ofFresh Tomatoes. Fruit softness is used as anindicator of quality but no numerical orquantifiable measurements are included in thestandards (Table 1). Thus, the designation of aparticular grade can be affected by a subjectiveassessment of fruit softness. Each individualproducer or produce inspector may have adifferent judgment of what constitutes a firm orsoft fruit and may even judge the same fruitdifferently under different conditions. Schotte, etal. (1999) compared the firmness ratings of fourmarket experts on tomatoes and found that expertscores varied dramatically. Therefore, it isdifficult for producers to accurately grade theirfruit before shipment or for inspectors to providean objective record of their assessment.

Various methods of quantitativelymeasuring fruit firmness have been developed.The most common methods for tomato use ameasurement of the resistance to puncturing(penetrometer) or the resistance to compression,measured as the force required to reach a standardcompression or as the amount of compressionunder a standard force, each in a given amount oftime (Adegoroye, et al., 1989; Ahrens, et al.,1987; Auerswald, et al., 1999; Jackman, et al.,1990; Kojima, et al., 1991). Kader et al. (1978)found that either system correlated well withsubjective ‘finger feel’ measurements. Althoughmuch of the research on tomato fruit firmness isthe result of laboratory testing, there are a fewreports of attempts to develop portable and lessexpensive instruments (Lesage and Destain, 1996;Sobotka, et al., 1972).

49

The objectives of this study were:

1) To identify the best quantifiablemethod(s) for measuring tomato firmnessby evaluating available equipment,considering factors such as accuracy,equipment portability, ease of use, priceand the ability to download data into acomputer.

2) To correlate objective measurements offruit firmness by the portable equipmentwith those of laboratory equipment andsubjective measurements to definetomato firmness on a quantifiable basis.

3) To evaluate the portable firmness testerunder ‘field’ conditions at destinationmarkets and compare results to thefirmness ratings provided by state orUnited States Department of Agriculture(USDA) produce inspectors.

Equipment evaluationWe investigated available tomato firmness

testers with the requirements that the equipmentbe portable, low-cost, accurate, and if possible,have thecapability to download data to a com-puter. Available equipment fell into two majorcategories; large and/or expensive penetrometersor deformation testers for use in laboratories, andhandheld or tabletop penetrometers. We purchaseda handheld penetrometer listed as suitable fortomatoes from the Fresh Products Branch of theUSDA ($210) (Figure 1). However, in furtherdiscussions with USDA personnel, it was decidedthat the contribution of skin thickness or toughnessto measurements of firmness when using apenetrometer would adversely affect the accuracyof the equipment for our use (Abbott, personalcommunication). In addition, with handheldpenetrometers, values can vary markedlydepending on the user. The destructive nature ofpenetrometer tests by puncturing or removing theskin would affect our ability to compare measure-ments from different pieces of equipment.

The decision was made to construct adeformation tester to our specifications. Measuringthe amount a fruit deforms (in units of length)under a specified weight and time period requiresless complicated equipment than measuring theforce required to deform a fruit by a specifiedamount in a given time period. Therefore, weevaluated models used at the University of Florida(UF) (a modified Cornell firmness tester) (Figure2) and the University of California (UC) thatmeasure amount of deformation rather than amountof force. As the UF model was too big, difficult touse for large fruit sizes, and had no digitalreadout capability, we modified the UC model.

The components of the IRREC deformationtester are: a metal stand with a flat base plate andan arm to hold the gauge, a digital distance gaugethat can read in inches or mm and can beconnected to a computer to download information,an attachment point for a probe or flat plate of avariety of sizes, an attachment point for a weightof variable size to adjust the amount of forceused, a collar to support the weight and protectthe gauge, a removable block with 60o and 90o

angles for use with the flat plates to equilibratepressure from all sides, and a cup for stabilizingfruit when using a probe (Figure 3). The improve-ments over the UC tester are increased flexibilityin use of plates or probes and an angled block orflat plate, and the ability to connect the tester to acomputer. After initial testing, the IRREC testerhas been further modified for use as a portablefirmness tester. It is now smaller and can beoperated by battery power. Total cost ofconstruction is approximately $700.

Evaluation of accuracy and comparisonto laboratory and subjectivemeasurements

The IRREC deformation tester wasevaluated at the IRREC Postharvest Laboratory.The initial plan was to compare the portabledeformation tester to a Texture Analyzer (Figure4), as a standard laboratory measurement of fruitdeformation. Red, breaker and mature green fruitwere tested in a preliminary trial with the UFdeformation meter and the Texture Analyzer

50

before the IRREC tester was completed (Table 2).While both methods showed increasingdeformation, and consequently decreasingfirmness, with increasing fruit maturity, thevalues for the Texture Analyzer were considerablylower than those for the UF tester. The TextureAnalyzer is so constructed that measurement ofdeformation does not begin until the force hasreached 1 kg even though the fruit is alreadybeing deformed. This time delay resulted in thelower measurements with the Texture Analyzercompared to those with the UF tester. Therefore itwas decided to compare the IRREC tester to theUF tester for the laboratory evaluation, as there isa body of research to support the UF tester as astandard method of laboratory evaluation oftomato firmness in Florida (Ahrens, et al., 1987;El Assi et al., 1997).

For the laboratory evaluation, FL 47 fruit atmature green, breaker and ripe stages, harvested 1day prior to the test, were subjectively dividedinto 5 firmness classes; very firm, firm, mediumfirm, soft, and very soft, with approximately 20fruit per class. Size and weight of 30 fruit weretaken to determine an average for the population(average fruit diameter 57 mm, average fruitweight 178 g). Each fruit was marked on oppositesides at the equator over the locules to indicatewhere the probes should be placed for the twomeasurements. Treatments were: IRREC meter at500 g for 5 sec with an 11 mm probe, IRRECmeter at 1 kg for 5 sec with an 11 mm probe, andUF meter at 1 kg for 5 sec with a 16 mm probe.The lower weight was used to determine if theamount of force affected the amount of fruitdamage. The test was repeated three times.

Table 3 shows the coefficients of variance(CV) as a measure of repeatability for the threetreatments for a single representative replicateof the data. While the CV’s for the UF testerwere lower in all cases than those for eitherIRREC tester treatment, they are in a similarrange. The larger probe on the UF tester mayhave resulted in the lower variability and probesize will be investigated for the IRREC testers inthe future. There is no consistent effect of amountof force on repeatability of measurements withthe IRREC tester.

The quantitative values associated with thesubjective measurements of tomato firmness arevery similar for the UF tester with 1 kg force andthe IRREC tester with 1 kg force (Figure 5). Withlower force and the same amount of elapsed time,the amount of deformation is lower, as is evidentwith the IRREC deformation tester with 0.5 kgforce. For all treatments, however, fruitsubjectively evaluated to be firmer had lowerdeformation values than fruit evaluated to be lessfirm. Tested fruit held at room temperature forthree days after evaluation showed thatindentations and consequent discoloring causedby the testers were more pronounced on softerfruit and with 1kg compared to 0.5 kg force. TheIRREC tester with 1 kg force caused moredamage than the UF tester with the same force.

These initial results suggest that the IRRECdeformation tester can be used successfully toquantitatively evaluate tomato firmness at a levelthat is equivalent to previously proven laboratoryequipment. The slight increase in variability ofmeasurements may be an acceptable tradeoff forthe greater adaptability of the IRRECdeformation tester to use by produce inspectorsat packinghouses and destination markets.

Evaluation of the IRREC firmness testerunder ‘field’ conditionsVisits to destination markets were delayed byproduction time for the firmness meter and theneed to have permission to work with the produceinspectors. However, visits to Washington, D.C,Tampa and New York City are scheduled forOctober 2001.

51

Literature Cited

Adegoroye, A.S., P.A. Jolliffe and M.A. Tung,1989, Textural characteristics of tomato fruits(Lycopersicon esculentum) affected bysunscald, J Sci Food Agric 49:95-102

Ahrens, M.J., D.J. Huber and J.W. Scott, 1987,Firmness and mealiness of selected Florida-grown tomato cultivars,Proc Fla State Hort Soc 100:39-41

Auerswald, H., P. Peters, B. Bruckner, A.Krumbein and R. Kuchenbuch, 1999, Sen-sory analysis and instrumental measurementsof short-term stored tomatoes (Lycopersiconesculentum Mill),Postharvest Biol and Tech 15:323-334

El Assi, N., D.J. Huber and J.K Brecht, 1997,Irradiation-induced changes in tomato fruitand pericarp firmness, electrolyte efflux, andcell wall enzyme activity as influenced byripening stage,J Amer Soc Hort Sci 122 (1):100-106

Florida Tomato Committee, 1998-1999, GradeRequirements, Regulatory Bulletin No. 1

Jackman, R.L., A.G. Marangoni and D.W.Stanley, 1990, Measurement of tomato fruitfirmness, HortSci 25(7): 781-783

Kader, A.A., L.L. Morris and P. Chen, 1978,Evaluation of two objective methods and asubjective rating scale for measuring tomatofruit firmness,J Amer Soc Hort Sci 103 (1):70-73

Kojima, K., N. Sakurai, S. Kuraishi, R.Yamamoto and D.J. Nevins, 1991, Noveltechnique for measuring tissue firmnesswithin tomato (Lycopersicon esculentumMill) fruit, Plant Physiol 96:545-550

Lesage, P. and M. Destain, 1996, Measurement oftomato firmness by using a non-destructivemechanical sensor,Postharvest Biol and Tech, 8:45-55

Schotte, S. N. De Belie, J De Baerdemaeker,1999, Acoustic impulse-response techniquefor evaluation and modeling of firmness oftomato fruit,Postharvest Biol and Tech 17:105-115

Sobotka, F.E., A.E. Watada and R.G. Diener,1972, Effectiveness of the pressure-loadmeter in measuring firmness of tomato fruit,HortSci, 7(1):34-36

United States Department of Agriculture,Inspector Training Manual, pg. 26

United States Department of Agriculture FreshProducts Branch Inspection Equipment,http://www.ams.usda.gov/fv/fpbdepot.htm

52

Table 3. Repeatability of tomato firmness readings from IRREC and UF deformation testers

Table 2. Comparison of tomato firmness readings from UF deformation tester andTexture Analyzer

Table 1. USDA firmness terms for tomatoes

mreT mreT mreT mreT mreT noitpircseD noitpircseD noitpircseD noitpircseD noitpircseD

draH.erusserpelbaredisnocot,llatafi,ylthgilsylnosdleiY

.decilsnehwpluproeciujfossoloN

mriF.erusserpetaredomotylthgilssdleiY

.decilsnehwtsolebyamsdeesroplup,eciujfospordwefA

tfoS.erusserpthgilsotylidaersdleiY

.decilsnehwsdeesroplup,eciujfossoL

USDA Inspector Training Manual for Tomatoes

egarevA egarevA egarevA egarevA egarevA )mm(noitamrofed )mm(noitamrofed )mm(noitamrofed )mm(noitamrofed )mm(noitamrofed

tnempolevedtiurffoegatS tnempolevedtiurffoegatS tnempolevedtiurffoegatS tnempolevedtiurffoegatS tnempolevedtiurffoegatS retsetnoitamrofedFU retsetnoitamrofedFU retsetnoitamrofedFU retsetnoitamrofedFU retsetnoitamrofedFU rezylanAerutxeT rezylanAerutxeT rezylanAerutxeT rezylanAerutxeT rezylanAerutxeT

deR 60.3 97.1

)50.92( z )30.63(

rekaerB 59.2 39.1

)77.42( )64.32(

neerGerutaM 73.1 88.0

)44.42( )21.62(

zFigures in parentheses are coefficients of variance

fotneiciffeoC fotneiciffeoC fotneiciffeoC fotneiciffeoC fotneiciffeoC ecnairav ecnairav ecnairav ecnairav ecnairav zzzzz

ssenmrifevitcejbuS ssenmrifevitcejbuS ssenmrifevitcejbuS ssenmrifevitcejbuS ssenmrifevitcejbuS yyyyy retsetFU retsetFU retsetFU retsetFU retsetFU gk1-retsetCERRI gk1-retsetCERRI gk1-retsetCERRI gk1-retsetCERRI gk1-retsetCERRI gk5.0-retsetCERRI gk5.0-retsetCERRI gk5.0-retsetCERRI gk5.0-retsetCERRI gk5.0-retsetCERRI

1 66.21 02.62 67.12

2 53.71 25.32 41.22

3 04.42 31.53 28.33

4 27.02 67.42 14.62

5 01.12 56.62 03.22

zThe higher the coefficient of variance, the more variability among measurements in the sample.ySubjective firmness ratings: 1 = very firm, 2 = firm, 3 = medium firm, 4 = soft, 5 = very soft

53

Figure 1. USDA penetrometer model

Figure 2. University of Florida deformation meter

54

Figure 3. IRREC deformation tester(Note variety of weights and probes/plate and angled block.)

Figure 4. Texture Analyzer

55

Figure 5. Comparison of UF deformation tester at 1 kg force with IRREC deformationtester at 1 kg and 0.5 kg force for quantifiable measurement of tomato firmness.(Values are averaged over measurements taken on both sides of the fruit andthree replicates.)

56

Sanitation and TemperatureManagement During Tomato Harvestand Packing Operations May AffectIncidence ofStorage Decay

Steven A. Sargent1, Jerry A. Bartz2,M. Tim Momol3 , Michael J. Mahovic2, Stephen M. Olson3, Phyllis R. Gilreath4

1Horticultural Sciences Department2Plant Pathology DepartmentUniversity of Florida, Gainesville3North Florida Research &Education Center, Quincy4Manatee County Cooperative Extension,Palmetto

AbstractSeveral new and on-going experiments

were conducted during this past year to provide abetter understanding of tomato packinghousesanitation. These experiments involvedcollaboration between grower/packer/shippers,county extension faculty, and extensionspecialists and researchers located throughout thestate. On-site visits were made to majorpackinghouses, in which dump tank sanitationwas monitored (free chlorine concentration, pH,temperature), and general sanitation programswere observed and discussed with management.Packers with automatic sanitation monitoring/controlling devices were encouraged toimplement a manual monitoring/verification plan.

During Fall 2000 and Spring 2001 seasons,extensive sampling was performed at severalpackinghouses in the Palmetto and Quincy areasto identify postharvest decay pathogens.Tomatoes were sampled before and after packing,and swabs were taken of packing line components,notably brushes and sponge rolls. Postharvest

decay bacteria and fungi were detected in thesamples from the Quincy area in both seasons.However, the extreme drought conditions duringboth seasons in the Palmetto area was most likelythe reason that no decay organisms were found insamples from that area.

Tomatoes from green to light-red ripenessstages were immersed in 104ºF (40ºC) water forup to 4 minutes to simulate dump tank handling.The tomatoes did not soften due to immersion,although riper tomatoes were softer than less ripetomatoes. This indicates that ripeness stage playsa more important role in susceptibility to bruisingthan does temporary heating of the skin duringdump-tank handling.

1. On-site VisitsNumerous visits were made to tomato

production areas from Quincy to Homesteadduring Fall 2000 and Winter/Spring 2001 seasonsto determine sanitation practices during handlingand packing. Dump tank conditions weremonitored (free chlorine concentration; pH;temperature; oxygen-reduction potential (ORP);residence times in tank; procedures followed bypackinghouse personnel). Extensive analyseswere made at regular intervals in packinghousesin the Palmetto/Ruskin and Quincy areas duringthe Fall 2000 and Spring 2001 seasons. Inaddition to measurement of dump tank conditions,other analyses included: water samples takenfrom the dump tanks, various fruit contactsurfaces on the packing lines were swabbed, andtomatoes were sampled before and after packing.

At the Postharvest Laboratory in Gainesvilleor the North Florida Research & EducationCenter-Quincy, microbes were plated out fromthese samples using specialized media to identifypotential pathogens or tomatoes were wound-inoculated with samples of wash water to find ifpathogens were present. During these visits,packinghouse managers were updated on watersanitation procedures and their equipment was

57

validated with our readings. Many of the packer/shippers were monitoring dump tank conditions,either manually or via automated sanitationsystems.

For several years we have recommendedthat packers install automated sanitationequipment to enable continuous monitoring andcontrol of dump tank conditions. Severalautomated systems are available that arespecifically designed for the challengingconditions encountered in tomato dump tanks.These systems often measure ORP and pH, andcorrelate these values to parts per million of free(active) chlorine; chlorine and an acidizer areadded to the on demand.

Our monitoring studies revealed that manyof the automated systems were performing withinUF/IFAS guidelines (see references below) toensure that postharvest decay pathogens werebeing effectively sanitized. However, at the timesof our visits, several systems were not meetingminimal requirements, providing a falseconfidence in the reliability of the equipment.The reasons for these systems not performingcorrectly ranged from poor system design, tofouled sensors, to inaccurate sampling of the tankwater, to failure to properly start-up the system(such as forgetting to turn on acid or chlorinefeed pumps).

These problems highlight the need for eachpackinghouse to monitor the performance of theautomated system at all times during packingoperations as part of the overall Best ManagementPractices established by the company. Aneffective dump-tank monitoring program shouldinclude:

• a written start-up procedure to ensurethat the sanitation system is functioningproperly prior to the start of packing,

• manually sampling dump-tank waterto determine free chlorine concentration,

pH, and temperature each 30 to 60minutes during packing,

• maintaining a record of these readingsfor future reference,

• comparing these readings with those ofthe automated equipment,

• having an action plan with correctiveprocedures in the event the system isfound to be working outside of acceptable levels.

2. Incidence of Decay Pathogens fromTomato Samples

Packing season and production area affectedthe populations of pathogens identified from thepackinghouse samples.

Palmetto/Ruskin areaIn Fall 2000 and Spring 2001, no significanttomato pathogens were identified from thesurfaces of tomatoes sampled before and afterpacking, nor from the swabs of packing linecomponents. The severe drought conditions weremost likely responsible for these unusually lowpopulations of pathogens in this production area.

Quincy areaIn addition to wound inoculation, the rinse fromtomatoes was also plated out on specializedmedia to quantify bacteria and fungi populations.In contrast to tomatoes from the Palmetto/Ruskinarea, significant incidences of sour rot and softrot decays developed in red-ripe tomatoesinoculated with the rinse water in both seasons.Rainfall amounts, though below normal levels,were higher than those during the seasons in thePalmetto/Ruskin area and, most likely wereresponsible for higher microbial populations inthis area.

58

Decays due to soft rot organisms wereprevalent in the Fall 2000 samples, and infectedwounds ranged from 41.5% on October 17 to16.2% on October 27 (Table 1). No decaysresulted from tomato samples harvested afterOctober 30. Washing decreased incidence ofdecay only for the first sample (Oct. 17);however, all other samples had similar incidencesof decay before and after packing. The onlyincidence of sour rot (Geotrichum spp.)developed from tomatoes packed after a 24-hourdelay(October 19/20). This demonstrates theimportance of packing tomatoes as soon afterharvest as possible. In Spring 2001, sour rot andsoft rot decays developed in wounds on allsamples (Table 1). With few exceptions, washedtomatoes had significantly less decay pathogensthan unwashed tomatoes (Table 2).

3. Mechanical Injuries and DecayDump tanks have been used for many years

to minimize mechanical injury to tomatoes duringthe transfer from field bins or gondolas to thepacking line. It has been reported that immersionin heated dump tanks caused ripening tomatoes(“pinks”) to be more susceptible to bruising thangreen-harvested tomatoes. To test this, ‘Florida47’ tomatoes were sampled the day of harvest(November 2000) at five ripeness stages: green,breaker (<10% red color), turning (10 to 30%),pink (30 to 60%) and light red (60 to 90%). Thesame day the samples were returned to thelaboratory and held overnight at 55oF (12.5oC)/85% relative humidity. The following day,tomatoes at each ripeness stage (n=5) weresubmerged for 1, 2, 3 or 4 minutes in 104oF(40oC) water to simulate immersion time in adump tank. Five tomatoes were not immersed asa control. Immediately upon removal from thewater bath, firmness was nondestructivelymeasured on the equator of each tomato(two readings/fruit) using an Instron Universal

Testing Instrument (convex-tip probe 0.4 inches(11 mm) in diameter and the force was recordedwhen the probe reached 1 mm deformation.

Results showed that tomato firmnessremained constant despite up to 4 minutesimmersion in heated water. Between ripenessstages (green to light-red), firmness decreasedsignificantly, from 2.2 to 1.1 lb-f (10.2 to 4.9Newtons), respectively. These results indicatethat ripening tomatoes are more susceptible tobruising due to softening that occurs duringnormal ripening, and not due to temporaryheating of the skin during dump-tank handling.Minimizing injuries (cuts, abrasions, punctures)during harvest and handling will further reducethe potential for development of decays duringhandling and shipping.

During Fall 2000, several packer/shippersreported observing white fungal growth at stemends of tomatoes in the ripening room. Uponfurther discussion, we learned that this fungalgrowth typically appeared on lots of tomatoesthat required from 6 to 8 days to reach breakerstage. This delay in ripening indicates that thetomatoes were being harvested at immature-greenstage. The extended ripening times necessary forthese tomatoes to reach breaker stage facilitatedthe growth of secondary fungi as the tomatoesripened at elevated temperature and relativehumidity. We previously reported (Proceedings1998 Florida Tomato Institute) that mature-greenharvested tomatoes should reach breaker stagewithin 3 days of gassing for maximum flavor andquality, and that tomatoes should be discarded ifbreaker stage isn’t reached after 5 days of gassing.

59

SummaryNatural populations of decay pathogens on

tomatoes fluctuate during growing season,however it is not yet possible to predict whenincreased populations might be introduced intothe dump tank water. Therefore, dump tanksanitation must be constantly maintained duringpacking. All surfaces that contact the tomatoesduring harvest and handling should be sanitizedon a regular basis to minimize the accumulationof decay pathogens.

Acknowledgments

We wish to thank Florida Tomato Commit-tee for partial funding in support of this researchand the excellent cooperation of the packer/shippers who collaborated in this study.

We also appreciate the excellent technicalassistance of the following individuals with datacollection and laboratory analyses: Abbie J. Fox,Horticultural Sciences Department, DianeConcelmo, Plant Pathology Department, andHank Dankers and Paula Bernsen, North FloridaResearch & Education Center-Quincy, Universityof Florida.

60

Table 1. Incidence of postharvest decays from green tomatoes sampled before and after packing. Tomatoeswere washed in sterile tap water and this rinse water was used to inoculate wounded, red-ripe tomatoes todetermine pathogenicity of bacteria and fungi. (5 punctures/fruit x 12 fruits/sample = 60 observations/samplelocation.) Quincy area.

*A=’FL 91'; B=’SunPride’; C=BHN 444.** Field samples. Dump tank simulated by surface treatment with 2% sodium hypochlorite for 2 minutes.

nosaeS nosaeS nosaeS nosaeS nosaeS etaDelpmaS etaDelpmaS etaDelpmaS etaDelpmaS etaDelpmaS yteiraV yteiraV yteiraV yteiraV yteiraV noitacoLelpmaS noitacoLelpmaS noitacoLelpmaS noitacoLelpmaS noitacoLelpmaStoRruoS toRruoS toRruoS toRruoS toRruoS

)%(ecnedicnI )%(ecnedicnI )%(ecnedicnI )%(ecnedicnI )%(ecnedicnItoRtfoS toRtfoS toRtfoS toRtfoS toRtfoS

)%(ecnedicnI )%(ecnedicnI )%(ecnedicnI )%(ecnedicnI )%(ecnedicnI

0002llaF tcO71 Aa niBdleiF 0 5.14

tcO71 A notraCdekcaP 0 5.1

tcO91 A )pihs-erp(niBdleiF 0 0.33

tcO91 A )pihs-tsop(niBdleiF 0 0.83

tcO02 A )pihs-tsop(notraCdekcaP 5.61 7.72

tcO42 A niBdleiF 0 5.11


tcO72 A niBdleiF 0 2.61


tcO03 A niBdleiF 0 0

tcO03 A notraCdekcaP 0 0

voN20 A niBdleiF 0 0

voN20 A notraCdekcaP 0 0

1002gnirpS nuJ91 B niBdleiF 5.1 0.33

nuJ91 B notraCdekcaP 5.6 7.21

nuJ22 B niBdleiF 2.8 7.42

nuJ22 B notraCdekcaP 0 7.91

nuJ62 B niBdleiF 0 7.93

nuJ62 B notraCdekcaP 0 5.1

nuJ92 C dehsawnU 0.3 2.11

nuJ92 C desniR b 0 0.3

luJ30 C dehsawnU **5.13 2.12

luJ30 C desniR b 2.61 7.9

luJ60 C dehsawnU 0 7.41

luJ60 C desniR b 0.3 5.1

61

Table 2. Microbial population data before and after packing. Tomatoes were washed in sterile tap waterand this rinse water was used to detect fungi and bacteria. Quincy area.

aA=’FL 91'; B=’SunPride’; C=BHN 444; D=’FL 47'.bIn 2000, acidifed PDA media was used for fungus detection and NA for bacterium detection.cIn 2001, acidified _ PDA media was used for fungus detection and NYB agar for bacterium detection.dField samples. Dump tank simulated

nosaeS nosaeS nosaeS nosaeS nosaeS etaDelpmaS etaDelpmaS etaDelpmaS etaDelpmaS etaDelpmaS yteiraV yteiraV yteiraV yteiraV yteiraV aaaaa noitacoLelpmaS noitacoLelpmaS noitacoLelpmaS noitacoLelpmaS noitacoLelpmaSairetcaB airetcaB airetcaB airetcaB airetcaB

)etalp/ufc( )etalp/ufc( )etalp/ufc( )etalp/ufc( )etalp/ufc(ignuF ignuF ignuF ignuF ignuF

)etalp/ynoloc( )etalp/ynoloc( )etalp/ynoloc( )etalp/ynoloc( )etalp/ynoloc(

0002llaF b tcO71 A niBdleiF 3.651 1.32

tcO71 A notraCdekcaP 9.82 0.0

tcO91 A )pihs-erp(niBdleiF 2.803 0.93

tcO91 A )pihs-tsop(niBdleiF 0.171 2.41

tcO02 A )pihs-tsop(notraCdekcaP 6.571 9.4

tcO42 A niBdleiF 2.231 3.61






voN20 A niBdleiF 2.48 2.81

voN20 A notraCdekcaP 3.09 2.901

1002gnirpS c nuJ91 B niBdleiF 3.763 0.15






nuJ92 C dehsawnU d 4.782 8.53

nuJ92 C desniR 0.521 3.3

luJ30 C dehsawnU d 0.004 1.611

luJ30 C desniR 9.61 2.0

luJ60 C dehsawnU d 0.004 4.322

luJ60 C desniR 5.55 3.0

luJ11 D dehsawnU d 0.004 3.393

luJ11 D desniR 6.36 2.0

luJ31 D dehsawnU d 30.004 9.98

luJ31 D desniR 6.181 2.0

62

Economics and Competitiveness inthe Florida Tomato Industry

John J. VanSickle, DirectorInternational Agricultural Trade andDevelopment CenterG-099 McCarty HallUniversity of FloridaP.O. Box 110240Gainesville, Florida 32611-0240

JustificationNAFTA and the Uruguay Round of

Multilateral Negotiations have liberalized tradeand helped in creating a more global market.While these agreements contain safeguards toprotect producers from sudden surges in importsor unfair trade practices, the safeguards havebeen inadequate in protecting Florida farmersfrom lower priced imports. Imports from Mexicoincreased after NAFTA was implemented andthe Florida industry sought relief from unfairlytraded imports. The U.S. Department ofCommerce concluded that Mexican shippers werein fact selling fresh market tomatoes at less thanfair value and negotiated a compromise withMexican producers where they agreed to stopselling tomatoes below a reference price that wasto be adjusted annually and was to be influencedby pricing practices for U.S. grown tomatoes.U.S. growers developed a floor pricing mechanismwhere they removed lower quality tomatoes fromthe market when prices fell to the floor price. Thefloor price was realized for much of the 1999/2000 production season, leaving growers toconsider alternative mechanisms for maintainingthe market price for fresh tomatoes.

Another issue that has grown inimportance is the growth in imports from sourcesother than Mexico. Just as a floor pricingmechanism was imposed for Mexican importsand for much of the domestically producedtomatoes, imports from Canadian and Europeanproducers of greenhouse grown tomatoesincreased. Imports from Canada alone increasedfrom 25 million pounds in 1996 to over 175

million pounds in 1999. European suppliers haveexperienced similar increases in market share inthe U.S. market. Greenhouse production of freshproduce is expanding throughout the world, withthe Mediterranean area of Europe producingabout 400,000 hectares of protected culture(1 hectare equals about 2.2 acres), of which100,000 hectares are greenhouses and the balanceis produced using low tunnels or mulching. Spainis the largest producing area in greenhouseculture with 46,000 hectares, with Italy holding25,000 hectares and France with 9,500 hectaresin greenhouses. Clearly, these producers arebecoming more of a force in the world market forfresh vegetables and particularly fresh tomatoes.

The need for understanding the economicsof these markets is as important as theunderstanding that was needed for dealing withmarket and trade issues in the 1990’s. Modelingof the U.S. vegetable industry has been critical tohelping policy makers understand the influencesthat are critical to Florida and U.S. producers. Amodel developed at the University of Florida wascritical to gaining a favorable ruling from theU.S. International Trade Commission in the morerecent trade dispute with Mexico. It has also beencritical to helping U.S. policy makers understandthe importance of methyl bromide in producingfresh vegetables in Florida and helped in extendingthe transition period for methyl bromide and inincreasing the commitment by the U.S.government for finding alternatives that willallow our producers to remain competitive.

At the same time that understanding theinfluences from international trade are important,it is also critical to understand the influences ofmarket structure on returns to Florida producers.Concentration in the retail sector has had aninfluence on returns to growers. The USDA hasinitiated a study of the market structure in thefresh produce industry, but it is critical forproducers to know how they can counter theinfluences from changes in market structure.

International trade and market structure areimportant influences in the fresh tomato market.It is critical that Florida producers understandthese influences and articulate their impacts on

63

producers and consumers. The economics of thisindustry and the competitiveness of suppliers arecritical to understanding the influences of policyand trade. New negotiations for a Free Trade Areaof the Americas (FTAA) and the Seattle Round ofNegotiations for the WTO will be critical to U.S.producers. It is critical that Florida producers beprepared to articulate their positions in thesenegotiations with data and research that will givethem more credibility in the policy arena. It iscritical that economics and competitiveness beunderstood in this important industry.

ObjectivesThe general objective of this research was

to extend the understanding of the U.S. vegetablemarket, including the impacts of imports ofgreenhouse tomatoes from Canada and Europeand to evaluate the influence of trading practicesused by suppliers from those regions. Specificobjectives were to:

1) Evaluate the cost of producing andimporting fresh tomatoes from Mexico.

2) Evaluate imports of fresh tomatoes.

Update on Mexican production costsProduction costs for field grown tomatoes

produced in Mexico were updated usingmethodology outlined by VanSickle in 2000.Table 1 shows the production costs for fieldgrown tomatoes produced in Sinaloa, Mexico.The key data required for updating the costs aremeasures of inflation and exchange rates. Theproducer price index indicates that costs increased9.21 percent from September, 1999 to September,2000. A factor of 1.0921 was therefore used toincrease the preharvest costs from the 1999/00production season to the 2000/2001 productionseason. The producer price index indicates thatcosts increased 6.77 percent from January, 2000to January, 2001, indicating that harvest andmarketing costs required an adjustment factor of1.0677. Interest rates declined in 2000 and aninterest rate of 16.77 percent was used for intereston preharvest expenses in the 1999/2000 season.

Yields were assumed to remain the same at 5,625cartons per hectare, with 4,500 exported. TheMexican peso increased in value with a reportedexchange rate of 9.761 pesos per U.S. dollar forthe 2000/2001 season. The average import valueof fresh tomatoes imported in the U.S. fromMexico in 2000 was $698.01 per metric ton ascompared to $795.99 per metric ton in 1999, a12 percent decrease.

Table 1 contains the updates in costs oftomatoes imported from Mexico. It shows thatcosts in Mexico increased from $7.16 per 25pound carton equivalent in 1999/00 to $7.42 per25 pound carton equivalent in 2000/2001, a 3.6percent increase. Costs have increased 37.4percent since the Suspension Agreement wassigned with Mexico (from the $5.40 per 25 poundcarton equivalent in 1995/96). These costs reflectincreases in costs resulting from inflation ininputs used to produce fresh tomatoes withadjustments made for changes in the exchangerate. The results indicate that Mexico received asignificant advantage from the rapid devaluationof the peso that occurred in late 1994 and 1995.Since then, inflation has increased costs forMexican producers and offset advantages theyheld immediately following the devaluation.

Imports of fresh tomatoesThe U.S. imported 730,063 metric tons

of fresh tomatoes in calendar year 2000 with animport value of $640.3 million (table 2). Mexicocontinues to be the leading supplier of importedtomatoes, supplying 589,954 metric tons with avalue of $411.8 million. Canada has become thesecond leading supplier of fresh tomatoes,accounting for $160.9 million dollars in importson 101,390 metric tons. The European Unionsupplied 34,696 metric tons of fresh tomatoeswith an import value of $59.1 million. Unitvalues for imported tomatoes declined forMexican suppliers, from $796 per metric ton in1999 to $698 per metric ton in calendar year2000. This compares to unit values of $1,587per metric ton for imports from Canada and$1,705 per metric ton from the European Unionin calendar year 2000.

64

The total value of all imports has declinedeach of the last three years, after reaching a highof $757.8 million in 1998 to $640.3 million in2000. Imports from Mexico and the EuropeanUnion have declined while imports from Canadaincreased from $100.6 million in 1998 to $160.9million in 2000. Canada has grown into a majorsupplier of fresh tomatoes in the U.S. market,increasing from $17.4 million in imports in 1995to the $640.3 million in 2000. Canada has beenthe only supplier to increase their value of im-ports in the U.S. market over the last 3 years.

Benefits to the Florida tomato industryThis research provided data necessary for

the Florida tomato industry to respond to issuesthat surface in the policy arena. The research alsoresulted in information that will allow growersand shippers to better understand influences inthis industry. This research helps the industry bebetter prepared to make the necessary decisionsfor preserving wealth and forging a new future.

65

Table 1. Production Costs for Field Grown Tomatoes produced in Sinaloa, Mexico.

1997-98Adj Pesos

3,5995,3767,733

22,46218,134

7,07519,255

2,803 86,437

44,78778,637

123,423

38,0206,0225,729

22,91772,688

282,54934,344

$6.11

1998-99factor

1.161.161.161.161.161.161.16

1998-99Adj Pesos

4,1756,2368,971

26,05621,035

8,20722,336

6,498103,514

52,92992,933

145,862

44,9326,0606,771

29,68387,445

336,82132,548

$5.79

1997/98

1.872.671.96

$ 6.50

1.782.511.88

$ 6.16

1998/99

2.112.992.06

$ 7.16

1999-2000

1999-2000factor

1.13821.13821.13821.13821.13821.13821.1382

1.10981.1098

1.1098

1.1098

1999-2000Adj. Pesos

4,7527,098

10,21129,65723,942

9,34125,423

3,814114,238

58,741103,137161,877

49,8654,2277,514

27,60889,215

365,33037,955

$6.75

1.09211.09211.09211.09211.09211.09211.0921

1.06771.0677

1.0677

1.0677

2000-2001factor

Expense ItemPre-Harvest Expenses

5,189 7,752 11,151 32,389 26,147 10,201 27,765

3,047123,641

62,717110,119

172,837

53,241 2,858 8,023

24,551 88,674

385,151 39,458

$7.01

2000-2001Adj. Pesos

2000-2001

2.253.152.02

$ 7.42

Land RentTransplantsFertilizersPesticidesLaborMachineryMisc/OverheadInterest - 55 daysSub-Total

Harvest & HaulPackingSub-Total

Transport to borderTariffOther Crossing FeesSelling FeesSub-Total

Total / Hectare (new pesos)Total / Hectare (Dollars)

Post-Harvest Expenses

Marketing Expenses

Dollars/25 lb. Carton

Export Cost / 25 lb. Carton

Total Preharvest/25lb CartonTotal Harv&PostHarv./25lbCartonTotal Exp. Mkt. Exp./25 lb Carton

Total Exp. Cost/ 25 lb Carton

1.18181.1818

1.1818

1.1818

Documents

2000-2001 Report of Tomato Research - Citrus · 2000-2001 Report of Tomato Research ... focused on the tomato industry of Florida. This is an extremely important partnership between