)/9/42829> :3 -?882< +:;?7/>6:9= :3 &?2 %0

HORTICULTURALENTOMOLOGY

Management of Summer Populations of European Red Mite(Acari Tetranychidae) on Apple with Horticultural Oil

A M AGNELLO W H REISSIG AND T HARRIS

Department of Entomology New York State Agricultural Experiment Station Geneva NY 14456-0462

J Econ Entomol 87(1) 148-161 (1994)ABSTRACT A highly refined horticultural petroleum oil Sunspray Ultra Fine was eval-uated in laboratory and field tests for efficacy against summer eggs and larvae of Europeanred mite Panonychus ulmi (Koch) Oil had significant ovicidal and residual larvicidalactivity in dip treatments at rates as low as 000005 but treatments using the same ratesin a Potter spray tower caused less mortality High-contact mortality of mite larvae sprayedin laboratory tests was obtained at rates of 025-100 Field applications of oil by airblastsprayer were tested during the summer for their ability to suppress mite populationsthroughout the growing season Effective control was achieved with three applications ofoil at 3 and 2 starting at the petal-fall stage and continuing on a 2-3-wk schedule A rateof 1 provided control under conditions of moderate population pressure but required anadditional spray in late July under severe population pressure Rates of 025 and 005resulted in unacceptable mite numbers by midsummer Phytotoxicity caused by the oil wasmost severe at the higher rates but oil caused no leaf drop even when trees weremoisture-stressed No effects of oil were seen on fruit finish or color except for an increasein scarf skin of Law Rome at the highest rates High-pressure handgun oil sprays againsta mixed population of mite eggs immatures and adults reduced motile forms by 79-95at rates of 2025

KEY WORDS acaricides Panonychus ulmi petroleum oil

DURING THE PAST SEVERALYEARSapple grow-ers in New York and other regions in northeast-ern United States and Canada have experiencedincreasing difficulty controlling European redmites Panonychus ulmi (Koch) These difficul-ties have been aggravated by a variety of factorsincluding the development of resistance to someof the most commonly used materials dicofol(Dennehy et al 1988) and cyhexatin (Welty et al1987) the unavailability or withdrawal of com-pounds because of regulatory decisions and de-lays in the registration of new acaricides Onemite-control method that has remained effectiveis horticultural petroleum oil used before bloom(Chapman amp Lienk 1966 Chapman 1967)

Oils have three principal advantages over con-ventional contact acaricides (Chapman 1967)First they have been determined to pose a smallhuman health hazard thus the Food and DrugAdministration exempts them from the require-ment of a tolerance A second advantage of oils isthe apparent inability of insects and mites todevelop resistance to them most probably be-cause of the oils presumed smothering mode ofaction Predatory mite populations are not aslikely to be severely affected by these spraysowing to the fact that the overwintering stages ofthese species (principally Amblyseius fallacis(Garman) and Typhlodromus pyri Scheuten) are

adult females (Lienk et al 1980) which may notbe as susceptible to suffocation by the oil be-cause of their motile nature Perhaps most im-portant oils demonstrate reliable efficacy at rel-atively low cost

Growers are interested in a strategy used asrecently as 15-20 yr ago of combining a lowrate of oil (095 liter379 liters of finish spraysolution) (025) for mite suppression with in-secticides and fungicides used during summercover sprays This was a common practice whenazinphosmethyl and benomyl were the predom-inant materials used to control apple maggotRhagoletis pomonella (Walsh) and apple scabVenturia inaequalis (Cooke) Winter respec-tively Currently however benomyl-resistantscab strains have been isolated from New Yorkorchards (Gilpatrick 1982) and the summer in-secticides and fungicides now used belong tomany different chemical classes so there aremany unknowns regarding spray compatibilitieseffectiveness and timing for this practice to berecommended implicitly without field testing

The development and refinement of petro-leum oils suitable for verdant plant use has beendiscussed by Chapman (1967) Johnson (1985)and Davidson et al (1991) including narrow-distillation range products specifically intendedfor summer use Lawson amp Weires (1991) dem-

0022-0493940148-0161$02000 copy 1994 Entomological Society of America

February 1994 AGNELLO ET AL SUMMER MITE CONTROL WITH OIL 149

onstrated acceptable control of P ulmi in an ap-ple orchard by applying three widely spacedsprays of different oil formulations at variousrates They also showed the ovicidal efficacy ofthese products against overwintering eggs Morepractical information is needed on the use ofdifferent oil rates during the summer on a pre-ventive basis to maintain a constant low level ofmortality of susceptible mites during a periodwhen populations are a mixture of all life stagesCurrent oil-use recommendations for mite con-trol are based on the assumption that because ofoils mode of action mortality is generally con-fined to the eggs and motile forms are able tosurvive oil applications However this assump-tion has not been investigated systematicallyWelty et al (1988 1989) demonstrated a 9- andll-fold greater susceptibility of summer thanwinter eggs of P ulmi to the ovicides hexythia-zox and clofentezine The objectives of our studywere to determine susceptibility of summer eggsto a narrow-distillation petroleum oil to provide abasis for recommending its use for seasonal con-trol as an alternative to contact materials

Materials and Methods

1989 Laboratory Bioassays Trials were con-ducted January-April using overwintering miteeggs on spur wood collected from commercialorchards the previous November and DecemberAfter storage at 2degC for 30-35 d to assure ade-quate egg chilling the spurs were held in a rear-ing chamber at 25degC and 40 RH under a pho-toperiod of 168 (LD) h to induce hatching thenplaced in close proximity to the foliage of pottedapple seedlings to allow colonization Summereggs were obtained by rearing the hatched mitesto the adult stage on the seedlings and transfer-ring them with a camels-hair brush to the topsurface of an excised leaf (20-25 adult femalesper leaf) set on moistened cotton in a petri dishThe excised leaves were bounded at the edgesby moist cotton barriers to prevent mites fromescaping Dishes were placed in the rearingchamber to allow the adults to lay eggs for 24 hafter which the cotton barriers and all motilemites were removed and the eggs were countedbefore the treatment was administered Serialdilutions of Sunspray Ultra Fine oil (viscosity68 s 50 distillation point 2122degC 10-90distillation range 183degC unsulfonated residue940 Mycogen San Diego CAl in distilled wa-ter were prepared to obtain test solutions of 3 21 075 050 025 010 005 0005 00005000005 and 0000005 but after several pre-liminary trials it was determined that the rangeencompassing nearly complete mortality to totalsurvival was represented by 005 0005 and00005 oil solutions on a volume basis Testleaves containing eggs were dipped for 5 s in200 ml of a test solution that was stirred con-

stantly until just before dipping to prevent phaseseparation For uniformity the three oil solu-tions and a distilled water check were mixed andtested concurrently using eggs from the samecohort with six replicate leaves containing 30-60eggs per treatment After dipping the leaveswere returned to their petri dishes in the rearingchamber The next day a bead of Tree Tangle-foot (Tanglefoot Grand Rapids MI) was placedaround the perimeter of each leaf and the eggswere recounted Leaves were examined forhatched larvae every 1-2 d and ovicidal mortal-ity was determined by comparing the number ofunhatched eggs with the original number of post-treatment eggs

Residual larvicidal effects of the oil solutionswere investigated in a similar manner to parallelan orchard situation where the summer egghatch occurs shortly before the application of anoil spray Adult mites (progeny of the overwin-tered egg generation) were transferred to cotton-bounded excised leaves as described above butthe laying arena was confined to a narrow areaimmediately surrounding the leaf midrib to facil-itate later manipulation After the eggs were laid(usually 3-4 d) and all the adult mites were re-moved this midrib portion of the leaf containingeggs was excised and placed onto the surface ofanother leaf that had been dipped in the oil-testsolution the previous day The same three con-centrations of oil as in the ovicide trials wereused as test solutions Dipped leaves wereplaced on moist cotton in a loosely covered plas-tic crisper and held in the rearing chamber for24 h at 25degC and 40 RH under a photoperiod of168 (LD) h to allow excess solution to run off orevaporate before midribs were placed on themA barrier of Tanglefoot was placed around theleafs perimeter to prevent mites from escapingand 3-4 d were allowed for hatch to occur Theleaf surface was examined and the numbers oflive and dead larvae plus those caught in thetanglefoot and those concealed on the undersur-face of the midrib were recorded and comparedwith the number of unhatched eggs on the mid-rib At the higher oil concentrations large num-bers of larvae were sometimes found under themidrib (not contacting the treated surface) orcaught in the tanglefoot barrier Because suchlarvae could have been exhibiting an escape re-sponse to the oil residue they were excludedfrom any calculations of larvicidal mortalitywhich was determined by comparing the num-ber of dead and live larvae on the treated surface

1990 Laboratory Bioassays Trials were con-ducted January-May using spur wood collectedthe previous fall and all the same ovicidal andlarvicidal assay procedures as in 1989 Serial di-lutions of oil in distilled water were prepared toobtain test solutions of 025 005 0005 00005and 000005 on a volume basis which was aslight expansion of the concentration range used

150 JOURNAL OF ECONOMIC ENTOMOLOGY Vol 87 no 1

previously The entire series of ovicidal and re-sidual larvicidal treabnents was then repeatedexcept that instead of being dipped into the oil-test solutions the leaves were treated usinga Potter Precision Laboratory Spray Tower(Burkard Manufacturing Rickmansworth En-gland) which is capable of producing a uniform-density spray mist of droplets in a narrow rangeof sizes Each leaf treated was placed individu-ally in the center of the target platform and thespray reservoir was filled using 5 ml of oil solu-tion that had been continuously agitated to pre-vent phase separation The contents of the reser-voir were then discharged at a pressure of 07kgcm2 onto the target platform a process requir-ing ==25s

1991 Laboratory Bioassays Ovicide-dip trialswere conducted April-June the same way as in1990 except that leaves containing the summereggs were returned to the rearing chamber for aperiod of either 24 or 48 h to obtain test groups ofeggs 24-48 or 48-72 h in age Results of the 1990summer field application trials indicated that Eu-ropean red mite larvae nymphs and adults ap-pear to be adversely affected by contact withsummer oil sprays We therefore wished to sup-plement this field observation by using the Pot-ter spray tower in the laboratory to expose motilestages of mites to a concentration series for mor-tality assessment Summer eggs were obtainedfrom mites hatching from overwintering eggsthat been brought into the laboratory DuringMarch and April nymphs from these eggs wereconfined on leaves using Tanglefoot barrierssprayed with different rates of oil and examined24 and 48 h after treabnent to evaluate survivalOil concentrations tested were 100 075 050and 025 and distilled water was used as acheck treabnent Contact larvicide spray trialswere conducted on a total of seven dates two orthree replicates were run on each date Eachreplicate of the trial comprised 10 leaves (2 perconcentration) treated on a given date usingmites of the same cohort for each days trial Theleaves were maintained in the rearing chamberat 25degC and 40 RH under a photoperiod of 168(LD) h during the time between treabnent andevaluation Any mites that reached a quiescentstage after the treabnent were tracked for 3-4 dto determine whether they would ultimately sur-vive the effects of the oil spray

1989 Airblast Field Trials Trials were con-ducted in four orchard blocks on different re-search farms of the New York State AgriculturalExperiment Station Geneva Station Creek(Red Delicious standard-sized trees) DarrowEast (McIntosh semidwarftrees) Darrow West(Red Delicious dwarf trees) and Hansen (Em-pire semidwarf trees) Each block whichranged in size from ==05to 10 ha was dividedinto a small (10-15 trees) untreated check andtwo treabnent sections which received either a

full-season or half-season oil program Spray ap-plications were made using an airblast sprayer(Friend 3750 Friend Manufacturing GasportNY) delivering 935 litersha All the treabnentplots received a 1 application of Suns pray6E emulsifiable oil (viscosity 75 s 50 distilla-tion point 2122degC 10-90 distillation range267degC unsulfonated residue 940 Sun Oiland Refining Marcus Hook PA) at the earlytight-cluster bud stage (4 May) and applicationsof 025 Sunspray Ultra Fine at the followingtimes pink bud stage (15 May) petal fall (3June) and first cover (22 June) The full-seasonplots additionally received applications of 025Sunspray Ultra Fine at second cover (1 July)third cover (15 July) and fourth cover (2 August)On 11 July and 9 August samples of 25 vegeta-tive terminal leaves were collected from each offour trees per treabnent plot brought to the lab-oratory and brushed with a mite-brushing ma-chine (Leedom Engineering Palo Alto CA) sothat numbers of European red mite eggs imma-tures and adults could be counted

1990 Airblast Field Trials A postbloom sum-mer oil program was tested in two commercialorchards in Wayne County (Law Rome nearSodus NY and Ida Red near Pultneyville NY)and one research orchard (Station Creek Em-pire and Cortland) in Geneva All received a1 Sunspray 6E spray at the tight-cluster budstage for early-season mite control The growersapplied these sprays in their respective orchardsbetween 25 and 30 April and the Station Creekorchard received an application of 1 Sunspray6E on 27 April The Sodus orchard was parti-tioned into six plots of 16 trees per plot (8 treeslong by 2 trees wide) for airblast oil applicationsplus an untreated check plot 5 trees long by 2trees wide The Pultneyville orchard was parti-tioned into three plots of 72 trees per plot (12trees long by 6 trees wide) plus an untreatedcheck plot 2 trees long by 6 trees wide TheStation Creek orchard was partitioned into threeplots of 15 trees per plot (5 trees long by 3 treeswide) plus an untreated check plot 4 trees longby 3 trees wide

Oil treabnents were applied in all locationswith an airblast sprayer as previously describedThe summer oil program using Sunspray UltraFine began at the petal fall stage and continuedon a 2-3-wk schedule for two or three coversprays Station Creek 14 and 23 May 14 Juneand 20 July Sodus 24 May 12 and 28 JunePultneyville 24 May 12 and 27 June and 18July The oil was applied at three different ratesin each orchard in accordance with the rangeshowing minimal to maximum effectivenessagainst European red mite eggs and larvae in thelaboratory trials high 100 medium 025low 005 (10 25 and 05 mill iter respective-ly) The check received no postbloom oil or aca-ricides


Leaf samples were taken for mite brushingstartin~ in early June on a 1-2-wk schedule totrack populations of European red mite eggs im-matures and adults Each sample consisted of25intermediate-aged leaves from each of four treesper treatment replicate Because high mite num-bers in the Pultneyville check and 005 oilplots be~an damaging the foliage by the sampletaken on 27 July a contact acaricide was appliedon 2 August and no additional samples were col-lected from these plots Fruit finish and injuryevaluations were made in these orchards usingfruit picked just before the respective harvestdates for each variety to assess the suitability ofthis projramin commercial fresh fruit blocks Oneach harvest date 400 apples (100 from each offour trees) were selected randomly in each of thetreatment plots and examined in the laboratory toevaluate fruit defects potentially attributable tothe oil sprays frost or mechanical damage thatmight have been exacerbated by the oil Defectswere classified as either light (damage minimalor absent) or severe Color ratings also were as-si~ned to the fruit according to USDA gradingstandards (USDA 1976) classifying fruit into oneof five categories according to percentage of redcolor cate~ories differed with the variety Addi-tionally in the case of Law Rome fruits wereevaluated for incidence of scarf skin a gray fleck-ing or milky appearance characteristic of this va-riety that can cause a lowering of the fruit gradeThe incidence levels chosen arbitrarily rangedfrom light (the lowest amount of flecking or dis-coloration seen in the samples) to moderate tosevere (the highest levels that occurred)

1991 Airblast Field Trials A postbloom sum-mer oil program was tested in two commercialorchards in Wayne County (Ida Red the samefarm as in 1990 near Sodus NY and the sameIda Red blocks as in 1990 near PultneyvilleNY) and the same research orchard as in 1990(Station Creek) As in 1990 all the orchards re-ceived a Sunspray 6E spray at the tight clusterbud stage for early-season control the growersapplied these sprays in their respective orchardsbetween 24 and 28 April and the Station Creekorchard received an application of 15 Sun-spray 6E on 26 April The orchards were parti-tioned into plots and airblast oil treatments wereapplied in the same manner as in the previousyear The summer oil program using SunsprayUltra Fine began at petal fall and continued on a2-3 wk schedule for two or three cover spraysStation Creek 20 and 30 May and 13 June So-dus 21 and 31 May 18 June and 24 July Pult-neyville 21 and 31 May and 18 June The oil wasapplied at three different rates in each orchardhigh 3 medium 2 low 1 (30 20 and 10mlliter respectively) The check received nopostbloom oil or acaricides

Leaf samples were taken to assess Europeanred mite numbers and fruit samples were taken

for evaluating finish and color in the same man-ner as in 1990 At the end of September leaf-phytotoxicity evaluations were made by examin-ing 50-100 terminal shoots throughout thecanopy of each of three trees in each plot in allthe orchards where these tests were conductedTrees were under moisture stress because ofweather conditions from May to August thatwere hotter (average temperatures 21-57degCabove normal) and drier (monthly rainfall accu-mulations 30-86 cm less than normal) than istypical for this region (US Dept Commerce1991) For this reason and because of the rela-tively high oil rates used in these plots leaveswere examined for the presence of the circularnecrotic lesions (1-2 mm diameter) characteristicof oil damage (Lawson amp Weires 1991) Eachterminal was categorized as clean (no lesions)slight (average of less than 5 lesions per leaf)moderate (average of 5-10 lesions per leaf) orsevere damage (average ofgt 10 lesions per leaf)

1990 Handgun Field Trials Sunspray UltraFine at three concentrations was tested in hand-gun applications for ovicidal efficacy comparedwith a standard contact acaricide (dicofol) againsta population of mixed-age European red miteeggs and motile forms in a research orchard inGeneva NY Oil treatments were applied on 21June and 9 July at the same rates as in the airblasttrials and dicofol (Kelthane 50 WP Rohm andHaas Philadelphia PA) at 227 g (AI)379 literswas applied on 21 and 29 June with a handgunsprayer (Friend Manufacturing Gasport NY)at apressure of 1026 kglcm2 All treatments includ-ing unsprayed check trees were applied to sin-gle-tree plots and were replicated three timesusing one Golden Delicious and two Red De-licious trees

On the day of the 21 July treatment after thespray residue was dry 10 leaves per tree werecollected from each of the plots and brought intothe laboratory A sufficient number of theseleaves were used to obtain 100-600 eggs fromeach replicate tree so that approximately = 1000eggs were evaluated per treatment Eggs werecounted on each leaf and all motile forms wereremoved from the upper surface with a camels-hair brush The leaves were then ringed withTanglefoot and placed in a rearing chamber at25degC and 40 RH under a 168 (LD) h photope-riod on wet cotton in individual petri dishes Onthe succeeding 2 d (24 and 48 h after treatment)all hatching larvae were counted and removed toseparate out effects of the treatments on eggs thatwere very close to hatching The leaves weremaintained in the chamber and examined forhatch several times over the next 12 d until hatchwas complete on the check leaves to determinethe rate of hatch in the different treatments Leafsamples consisting of 25 intermediate-agedleaves from each of four trees per treatment rep-licate were taken for mite brushing on 19 June


Table I Mortality (SEM)of European red mite egg and larvae treated by dip or pray applications of petroleum oilin the laboratory

Oi] n Mortality n Mortality

1989 Ovicide Tests Residual Larvicide Tests(0-24-h Eggs)

Dip Treatments005 594 987 (16) 506 880 (111)0005 568 894 (111) 395 660 (359)00005 550 690 (339) 336 558 (303)0 522 193 (136) 435 02 (06)


Dip Treatments025 476 1000 (00) 84 1000 (00)005 473 992 (23) 123 1000 (00)0005 464 950 (140) 178 1000 (00)00005 548 772 (268) 149 687 (391)000005 401 519 (295) 125 572 (205)0 458 181 (76) 112 174 (155)Spray Treatments025 335 561 (312) 124 922 (137)005 350 194 (109) 98 34 (42)0005 327 185 (108) 117 14 (17)00005 316 138 (68) 103 128 (198)000005 323 163 (92) 97 16 (32)0 302 163 (55) 113 28 (41)1991 Ovicide Tests

(24-48-h Eggs) (48-72-h Eggs)Dip Treatments025 212 1000 (00) 252 980 (32)005 195 1000 (00) 185 1000 (00)0005 203 992 (20) 246 970 (39)00005 197 963 (91) 196 799 (252)000005 196 1000 (00) 201 730 (286)0 225 205 (76) 200 139 (148)

Standard error of mean calculated among replicates for each treatment rate

2 d before the first spray was applied and on 28June 2 and 24 July and 3 and 8 August Thispermitted monitoring of European red mite eggsimmatures and adults in all of the treatmentplots

1991 Handgun Field Trials Sunspray UltraFine was tested at four concentrations for its ovi-cidal efficacy and residual control against a pop-ulation of mixed-age European red mite eggs andmotile forms in a research orchard at Geneva Oiltreatments were applied as described for 1990 on12 July to single-tree (Red Delicious) plots rep-licated four times at the following rates 3 2 1and 025 (30 20 10 and 25 mlliter respec-tively) Eggs were collected in the same manneras in the previous year and evaluated for hatchon 18 and 23 July and any live mites were de-termined to have survived the treatments Leafsamples consisting of 5-10 intermediate-agedleaves from each of four trees per treatment rep-licate were taken from the trees for direct visualexamination under a dissecting microscope inthe laboratory Samples were taken on 9 July 3 dbefore the handgun spray and 3 10 18 and 42 dafterward to track populations of European red

mite immatures and adults in all of the treat-ments

Because of the nature and plot size of the air-blast trials true spatial replication was not pos-sible within each site therefore no analysis ofvariance (ANOV A) or inferential statistical pro-cedures were used on the summer mite countsfrom these treatments Instead the mean valuesare presented together with their standard errorsAll mortality percentages fruit color and leaf-damage counts were subjected to an arcsinesquare root transformation ANOVA and a leastsignificant difference test (Proc ANOVA SAS In-stitute 1985) were used to separate treatmentmeans with a comparison wise error rate oflt005

Results and Discussion

1989 Laboratory Bioassays Because of thehigh variance obtained in the analyses of thetreatment effects the laboratory assays were re-peated several times Total mortality was causedby all test solutions stronger than 005 and nosignificant mortality resulted from test solutionsweaker than 00005 (Table 1) In both the ovi-


Table 2 Contact mortality (SEM)of European red mite larvae p bullbullbullbullyed with petroleum oil in the laboratory 1991

24-h reading 48-h readingOil n In In Dead barrier Dead barrier

100 146 796 (287) 96 (134) 888 (135) 112 (135)075 145 906 (120) 67 (93) 932 (93) 68 (93)050 157 848 (216) 41 (81) 953 (92) 47 (92)025 171 730 (186) 64 (87) 926 (90) 70 (91)Check 168 39 (74) 48 (63) 62 (114) 63 (90)


11 July 1989100 250

0 Chadlt

80 rn Half-Season 200-III bull Full-Seasonj

i 60 1500Z 40 100r

i 20 50

0 0Eggs Motiles Eggs Motiles Eggs Metiles Eggs Metiles

Darrow West Darrow East Hansen Station Creek

9 August 1989

o Check

ill Half-Season

bull Full-Season

MotilesEggso

400

800

1600

2000

1200

Eggs MotilesEggs Motiles Eggs Motiles

100

o

400

500

bullbull3008~r 200IIICII~

-IIICIIJ

Darrow West Darrow East Hansen Station CreekFig1 Mean number plusmn SE of European red mites on trees receiving a tight-cluster oil spray plus a half-season

(pink petal fall and first cover) or a full-season (half-season plus second third and fourth cover) program of 025Sunspray Ultra Fine oil Geneva


Sodus 1990 Pultneyville 1990

Fig 2 Mean number plusmn SE of European red miteson trees receiving a tight-cluster oil spray plus threepostbloom sprays of Suns pray Ultra Fine oil at differentrates Wayne County

-e-Check-+-005 Oil

--- 025 Oil____ 1 Oil

520 64 619 75 720 84 820

Fig 3 Mean number plusmn SE of European red miteson trees receiving a tight-cluster oil spray plus fourpostbloom sprays of Sunspray Ultra Fine oil at differentrates Wayne County

o

60

liii 50CD

Ibull 40CDQ 30ciz 20cIII

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o100

liii 80CD

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lii 60Q

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10- 8IIICDI 6CDQ

ci 4zcIII 2CD~

0

30- 25IIICD

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t520 64 619 75 720 84 820

cidal and residual larvicidal tests mite mortalitydecreased with concentration and the lowestconcentration (00005) caused greater mortalitythan did the check Our examination of residuallarvicidal effects was intended to parallel a fieldsituation where the summer eggs are not con-tacted by oil directly and the larvae hatch ontothe residue of a treated surface The three con-centrations tested using this indirect method ofexposing European red mite larvae to oil alsoresulted in greater mortality than the check sug-gesting that a summer oil treatment may be morethan a contact pesticide

1990 Laboratory Bioassays As in the 1989tests 100 mortality was caused by the dip-solution treatment of 025 However unlikethe 1989 egg-dip assays the 000005 rate re-sulted in higher mortality than that obtained inthe check The residual mortality effects on lar-vae placed on treated leaves are similar to thoseof the eggs with no difference among the threehighest concentrations (025-0005) and thenincreasingly higher survival with lower concen-trations Although the Potter unit produces aspray of virtually ideal characteristics the con-centrations applied as a spray did not have the

same effect on European red mite eggs as whenthe entire leaf was immersed in solutions of thesame concentration Mortality increased be-tween the 005 and 025 treatments indicat-ing a transition point at which the discrete spraydroplets were able to coalesce sufficiently to par-allel the action of a continuous residue as in thedip trials

1991 Laboratory Bioassays Several repetitionsof the ovicidal bioassays were conducted be-cause of the high variance As in the 1990 tests on0-24-h-old eggs the 025 treatment caused100 mortality of the 24-48-h-old eggs but 2of the 48-72-h-old eggs survived this concentra-tion (Table 1) As the oil concentrations de-creased the mortality responses were variableamong the different age classes The 24-48-h-old eggs were susceptible to all rates of oilWith the newly laid eggs and the oldest eggshowever the two lowest rates-0OO05 and000005-caused less mortality in newly laideggs and the oldest eggs than did the higherrates Winter eggs become more susceptible topetroleum oil as they near hatching which is theperiod from apple-bud dormancy to the tight-cluster stage This corresponds to =39 and 6 d

February ~994 AGNELLO ET AL SUMMER MITE CONTROL WITH OIL 155

510 528 616 75 723 811 830

Station Creek 1990

Fig 4 Mean number t SE of European red miteson trees receiving a tight-cluster oil spray plus fourpostbloom sprays of Sunspray Ultra Fine oil at differentrates Geneva

1989 Airblast Field Trials Population countsof European red mite life stages taken two timesin each plot during the summer show the effectof treatment (Fig 1) The untreated check plotsat the Darrow East and Hansen locations had lownumbers of mites Late May rains and temperateearly-summer weather were not favorable forEuropean red mite population growth during thefirst part of July although some treatment differ-ences were clear in the Hansen block by thisdate Above-average temperatures (32degC higherthan normal) (US Dept Commerce 1991) in lateJuly allowed rapid mite buildup before the Au-gust count and in most cases the numbers ofmites in the full-season plots were lower thanthose in the respective half-season and checkplots However because of the large variabilityamong the sample counts from one tree to thenext these differences were not always uniformAlthough no systematic evaluation ofleaf qualitywas made during the season no injury to thefoliage was evident in any of the treatment plots

1990 Airblast Field Trials The summer mitepopulation was affected by oil concentrationThe Sodus orchard (Fig 2) had low summer mitepopulation densities and never exceeded recom-mended thresholds (June 25 July 50 and Au-gust 75 mites per leaf) (Wilcox et al 1993)through July Numbers started to increase in Au-gust however and on 14 August (6 wk after thelast oil spray) mite numbers in the treatmentplots varied inversely with the oil rate Numbersincreased more rapidly in the Pultneyville or-chard (Fig 3) and counts were lower in the 1plots on all sample dates threshold numberswere never reached in these trees and mitesremained below threshold even in the 025plots until mid-July The check and 005 plotsreceived sprays of a conventional contact acari-cide at the end of July to prevent foliar bronzinginjury from mite feeding Results of the oil treat-ments were similar at Station Creek (Fig 4) ex-cept for low populations in the check trees Thepredatory mite Typhlodromus pyri Scheutenwas found at low levels (002 per leaf) in the 3August 2 and 3 Pultneyville plots and in the14 August 1 and 2 Sodus plots The stigmaeidmite Zetzellia mali (Ewing) was found in theStation Creek plots on the 3 8 and 23 Augustsampling dates at levels of 07-27 per leaf andby 23 August the ntImbers in the treated plots(23-27 per leaf) were significantly higher thanthose in the checks (16 per leaf) (F = 374 df =6 9 P = 00538 These counts are typical ofpredatory mite population levels in New Yorkapple orchards but are not high enough to haveinfluenced European red mite numbers in theoil-treated trees (Lienk et al 1980) Overall the1 spray program successfully maintained mitesbelow threshold levels for the period of the sea-son that contact acaricides normally are used incommercial plantings

---e- Check~0050i1---- 025 Oil--lOil

~lTT T ~ T1 1

respectively before the start of hatching (Chap-man amp Pearce 1949) Welty et aI (1988 1989)demonstrated that as both summer and wintereggs progressed to within 1-2 d of hatching theirsusceptibility to the acaricides hexythiazox andclofentezine decreased Our results are similar inthat the oldest age class of eggs tested (3-4 dfrom hatching) were less susceptible to the oiltreatments than eggs 24 h younger

Results of the contact larvicide spray trialsshow a mortality effect of all rates of oil tested(Table 2) Mites found in the tanglefoot barrierswhich could not be counted as alive or dead arereported separately Our data show that newlyemerged larvae and nymphs are unable to sur-vive for gt48 h after direct contact with thesesprays In these trials low concentrations of oilcaused up to 100 mortality of mites comparedwith field rates of 025-100 that generally donot control mite populations in the orchardThese low concentrations can be used under lab-oratory conditions because complete leaf cover-age was achieved by immersing leaves in the oilmixtures or spraying them with an idealizedspray and degradation or volatilization of theresidue was not influenced by weather

o

50

35- 30bullCD25I

l 20

~ 15

c 10bullCDIE 5

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i 30

ci 20zc 10

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bullbull 40CDI


Table 3 Fruit and leaf quality at harvesl from trees receiving a prebloom oil spray and various postbloom oil sprayprograms Wayne Counly and Geneva 1990-1991

ParameterTreatment

Check 005 Oil 025 Oil 1 Oil

1990Sodus (Law Rome 24 Oct)

Scarf skinLight 495a 358a 280a 270aModerate 335a 390a 418a 408aSevere 170a 253ab 303b 323b

Fruit damagemiddotbLight 130a 125a 70b 140aSevere 65a 28a 35a 25a

Red categorylt25 68a 58a 88a 138a25-40 248a 215a 240a 355a41fj6 2403 393a 415a 340a67--80 243a 258a 205a 140agt80 185a 80a 53a 33a

Station Creek (Empire 24 Sept)Fruit damagemiddotb

Light 43a 45a 50a 35aSevere O3a OSa OSa lSa

Red categorylt25 OOa 03a OOa LOa25-40 70a 38a 28a 48a41-66 180a 218a 178a 138a67-80 355a 450b 425ab 453bgt80 388a 345a 375a 353a

Pultneyville (Ida Red 8 Oct)Fruit damageb

Light 58ab 80a 33b 75aSevere 05a 08a 08a 13a

Red categorylt25 118a 150a 33b 28b25-33 263a 260a 230a 155b34-50 293a 290a 343a 283a51-80 263a 238a 318a 348agt80 95ab 83b 88b 188a

Station Creek (Cortland 24 Sept)Fruit damagemiddotb

Light 90a 88a 53a 93aSevere 15a 40a 23a 18a

Red categorylt25 45a 25b 25ab 08b25-33 233a 153ab 208a 95a34-50 283a 240a 263a 273a51--80 353a 395a 350a 390agt80 85a l70ab 130a 243b

1991Station Creek (Empire 1 Oct)

Foliar lesionsClean 90a 162a 22a 126aSlight 697a 616a 499ab 392bModerate 213a 210a 401a 346aSevere OOa 12ab 79ab 141b

Red categorylt25 03a OOa LOa OOa25-40 25a 88a 130a 05a41fj6 300a 335a 308a 233a67--80 415a 380a 403a 443agt80 303a 223a 170a 343a

Sodus (Ida Red 2 Oct)Foliar lesions

Clean 923a 804a 63lb 252cSlight 77a 196ab 362bc 536cModerate OOa OOa 07a 189bSevere OOa OOa OOa 17b

Red categorylt25 05a 03a 03a 28b25-33 13a 38ab 28ab 63b34-50 188a 243a 215a 263a51-80 613a 560a 558a 540agt80 173ab 158ab 200a 103b


Table 3 Conlinued

TreatmentParameter

Check 005 Oil 025 Oil lOiJPultneyville (Ida Red 2 Oct)

Foliar lesionsClean 173a 327b 307b 1O8aSlilht 638ab 652a 529b 55labModerate 18Ia 2Ib 157a 304aSevere 08a OOa 07a 38a

Red catelorylt25 LOa OOa 03a 03a25-33 83a 33a 85a 70a34-50 408a 285a 425a 380a51-80 500a 588a 445a 525agt80 OOa 98c 45bc 28b

Station Creek (Cortland 16 Sept) Red calelory

lt25 28a 83b 33ab 50ab25-33 165a 205a 180a 180a34-50 338a 278a 298a 300a51-80 465a 363a 450a 458agt80 08a 65b 40ab 40b

Treatment means followed by the same Jetter are not significantly different (for 1990df = 6 9 Scarf skin light F = 089 P =05420moderate F = 132P = 03385 severe F = 191P = 01834Fruitdamale Law Rome light F = 282P = 00791severeF = 079 P = 06000 Empire IilhtF = 092 P = 05209 severe F = 065 P = 06909 Ida Red IilhtF = 259 P = 00964severe F = 030 P = 09219 Cortland light F = 078 P = 06072 severe F = 128P = 03538 Red cateloryLaw Rome1 F = 066 P = 068242 F = 099 P = 048503 F = 137P = 032304 F = 118P = 039575 F = 073 P = 06407 Empire1 F = 172P = 022192 F = 373 P = 003803 F = 264P = 009254 F = 219P = 013985 F = 280P = 00805 Ida Red1F = 494 P = 001672 F = 1129P = 000093 F = 125P = 036754 F = 110P = 043285 F = 319P = 00581 Cortland1 F = 433 P = 002482 F = 392 P = 003303 F = 047P = 081194 F = 066P = 068515 F = 289P = 00741For 1991foliar lesions df = 38 Station Creek clean F = 176P = 02329 slight F = 397 P = 00528 moderate F = 247 P = 01360severe F = 343 P = 00724 Sodus clean F = 000 P = ooslightסס1 F = 2271P = oo1moderateסס0 F = 1086P = 00010severe F = 8388 P = 00001 Pultneyville clean F = 944 P = 00053 slight F = 327 P = 00800 moderate F = 1193 P =00025 severe F = 049 P = 06964) Red category df = 69 Empire 1 F = 073 P = 055142 F = 183P = 01957 3F = 056 P = 06484 4 F = 022 P = 08788 5 F = 149P = 02662 Sodus Ida Red 1 F = 334 P = 00334 2 F = 254 P =00767 3 F = 135 P = 02783 4 F = 074 P = 05377 5 F = 158P = 02154 Pultneyville Ida Red 1 F = 045 P = 072462 F = 174P = 021123 F = 184P = 019324 F = 125P = 033515 F = 693P = 00058 Cortland 1F = 183P = 019462 F = 029 P = 083523 F = 062 P = 061634 F = 069 P = 057685 F = 366 P = 00041)least silnificantdifference test[SASInstitute 1985])Percentales subject to arcsine square root transformation before analysis

a Average percentage fruit or leaves per categoryI Fruit surface damaleattributable to frost or mechanical injury

Fruit quality harvest evaluations show that thehigher oil concentrations significantly affectedthe proportion of Law Rome fruit with severescarf skin levels at the 025 and 1 rates wereapproximately double the check incidence (Ta-ble 3) The proportion of fruit with light or mod-erate damage was not affected by any of the treat-ments The fruit-damage category was includedto address the possible interaction of oil andweather-related injury which in turn is oftenindistinguishable from certain types of physicalbruising The oil treatment did not appear tohave any bearing on this type of injury in any ofthe varieties The only treatment differencesfound in the color ratings were in direct relation-ship to the oil concentration where greater pro-portions of the Cortland and Ida Red some-times occurred in the higher color categorieswith increasing oil concentration

1991 Airblast Field Trials The mite popula-tion was affected by oil concentration The Pult-neyville orchard (Fig 5) had low summer mitepopulations and no above-threshold counts

were seen in the treated plots throughout theentire season Numbers of mites in the checkplots increased in August however and re-mained high Mite populations increased morerapidly in the Sodus orchard (Fig 6) which hadsevere population pressure during most of thesummer Numbers in all plots remained belowthreshold into July but exceeded acceptable lev-els in the 1 trees by the middle of that monthThis necessitated the additional application ofthe 1 treatment on 24 July which reduced mitenumbers but only for approximately 2 wk The 2and 3 treatments kept the mites below thresh-old levels all season but counts were signifi-cantly lower in the 3 plots on all sample datesfrom 15 July through August The mite popula-tion at the Station Creek orchard (Fig 7) re-mained low throughout the season and neverexceeded the threshold

At the Pultneyville site T pyn was present inthe samples on 28 June and thereafter but num-bers were higher in the treatment plots (11-29per leaf) than in the checks (02-03 per leaf)


83089720629

Sodus 1991

69

Pultneyville 199135 100

30 --e--- Check- --+-1 Oil - 80bullbull 25 -A-2Oil bullbullCI CII____ 3Oil

I 20 bull 60CI CIa a0 15 0 40Z Zc 10 c 20bullbull bullbullCI 5 CI2 2

0 0

20 35

30- 15 -bullbullCI bullbull 25I CII 20CI 10 CIa a

ci 0 15Z 5 Zc c 10bullbull bullbullCI CI 52 0 2

t t 0

520 69 629 720 89 830 520

Fig 5 Mean number plusmn SE of European red miteson trees receiving a tight-cluster oil spray plus threepostbloom sprays of Sunspray Ultra Fine oil at differentrates Wayne County

Fig 6 Mean number plusmn SE of European red miteson trees receiving a tight-cluster oil spray plus three orfour postbloom sprays of Sunspray Ultra Fine oil atdifferent rates Wayne County The 24 July spray wasapplied to the 1 plots only

only on 31 July (F = 753 df = 6 9 P = 00041)and 7 August (F = 1116 df = 69 P = 00010)The check plots had significantly higher num-bers of predator mites than oilmiddottreated trees onlyon 28 June (F = 686 df = 6 9 P = 00057) Atthe Sodus site T pyri was seen on 31 July and 7and 21 August and numbers in the 3 plots (06per leaf) were greater than in the checks (03 perleaf) only on the last of these dates (F = 298df = 7 24 P = 00513 At the Station Creek siteZ mali was present on 28 June and on all sub-sequent sample dates but its numbers in thetreatment plots (25 per leaf in 3 oil trees) ex-ceeded those in the checks (13 per leaf) only on29 July (F = 228 df = 6 9 P = 01483 Ingeneral the 2 and 3 oil treatments success-fully controlled mites during a severe mite infes-tation without the need for contact acaricidesThe 1 rate at the Sodus site required additionalapplications to prevent unacceptably high num-bers

Phytotoxicity occurred mainly in those por-tions of the canopy where the spray had driedunevenly or had accumulated after the applica-tion such as locations adjacent to the sprayer andat the ends of leaf terminals (Table 3) Oil con-centration significantly affected the proportion of

foliar shoots with severe lesions causing levels2-fold higher with the 3 than the 2 rate in theEmpire trees at Station Creek Although thedata for Ida Red were more variable leaf dam-age tended to increase with higher oil concentra-tion The high temperatures and moisture stressexperienced during the summer of 1991 contrib-uted to overall poor leaf quality in many orchardsaround the state and leaf damage observed atStation Creek and Pultneyville were confoundedby the occurrence of similar lesions in all thetrees caused by nutrient deficiencies No leafdrop and no damage to fruit finish was observedin any of the plots

As in the 1990 trials none of the oil treatmentsaffected fruit color Oil-treated fruit from thePultneyville site was gt80 red 28-98 of thetime whereas none of the check fruit was placedin this category (Table 3) At the Station CreekCortland site higher proportions (40-65) offruit receiving 10 and 30 oil sprays was clas-sified similarly (gt80 red) than was fruit fromcheck trees (08)Although it is not possible toascribe enhanced red color to the oil treatmentsit is clear that the oil had no adverse effect on

AGNELLO ET AL SUMMER MITE CONTROL WITH OIL

518 67 628 719 89 830Fig 7 Mean number plusmn SE of European red mites

on trees receiving a tight-cluster oil spray plus threepostbloom sprays of Sunspray Ultra Fine oil at differentrates Geneva

fruit color for the 2 yr these evaluations wereconducted

1990 Handgun Field Trials Oil sprays appliedby handgun had a significant effect on egg sur-vival although less than the laboratory assays(Table 4) Percentage of egg hatch decreased atthe higher oil rates although none of the meanvalues were statistically different The large vari-ability in the readings was similar to that ob-served in the laboratory ovicide tests Despitethe apparently low egg mortality in the treatedtrees the low subsequent population counts on28 June and 2 July 7 and 11 d after the applica-tion date indicate that population growth wasbeing suppressed in the treated plots (Table 4)This trend continued until 24 July in the 1treatment 33 d after spraying These results par-allel those of the airblast trials and suggest thatoil residue on the leaf surface may have larvi-cidal activity against the immature mites

1991 Handgun Field Trials Oil treatmentscaused greater egg mortality than was observedduring the 1990 trials including those ratestested both years Percentage of hatch was lt10in all treatments (F = 055 df = 69 P = 07612)(Table 4) Mortality of mites that survived afterhatch was not significantly different among treat-

159

ments Approximately 25 of the mites thathatched out of eggs treated with the 025 ratesurvived (29 mites out of 524 eggs) Howeverthis was not significantly different from thehigher rates where almost none survived (F =150 df = 6 9 P = 02801)

Similar results were obtained from the orchardcounts of mite numbers in the sprayed trees (Ta-ble 4) The initial postspray counts (on 15 July3 d after treatment) show a gt95 reduction inmotile forms with a concentration of 1 orhigher and in the 025 oil plots the reductionis 79 Populations in all plots peaked 1 wklater then subsided to below-threshold levels byAugust These results indicate that the ratestested may reduce mite numbers effectively byboth contact and residual activity if spray cover-age is optimal

In conclusion our results demonstrate thatsummer oil applications can control Europeanred mites effectively in apple orchards In thelaboratory both contact (immersion and spray)and residual oil treatments at low applicationrates can kill the larval and egg stages of themite Although an optimal oil treatment is capa-ble of mite population suppression during thesummer growers must address the problems ofachieving optimum spray coverage under normalfield conditions using standard airblast sprayersCaution is necessary in exercising mite controlstrategies that include the use of petroleum oilproducts Oil has not been an effective rescuetreatment for extremely high populations (un-published data) and it is incompatible with sul-fur-based fungicides Also as seen in 1991 con-ditions of high temperature and moisture stressincrease phytotoxicity caused by oil sprays Thescarf evaluations indicated that certain varietiesmay be sensitive to summer oil applicationsHowever apple mite management programs caninclude summer applications of highly refinedhorticultural oils which may be tank mixed withother crop protectant materials to limit Europeanred mite population growth

Acknow ledgments

We thank S Brownell and G Orbaker for allowingus to work in their orchards We also thank D DunhamH Hebding C Smith J Minns Jr K Davis K Han-nacker P Hezel E Minson C Momberger D Note-baert N Rivkin S Spangler J Wagar H Wilcox MWilcox T Wheeler S Young J Kovach and D Was-son for their technical assistance Special thanks go toN Wright and R Stewart for providing the petroleumoil to D S Lawson and J Nyrop for reviewing earlierversions of this manuscript and to P J Chapman forhis guidance and counsel This project was partiallyfinanced with funds from Sun Refining and MarketingCompany and the New York State Department of Ag-riculture and Markets Albany

Station Creek 1991

February 1994

10

- 8IICDJbull 68-ci 4zc 2IICDE

0

6

5-IIICD4Jbull

8- 3

~ 2cIICDE

0


Table 4 Hatch residual larval mortality and summer populations of European red mite on trees receiving handgunspray of petroleum oil Geneva 1990-1991

TreatmentParameter

Check 005 025 1 2 3 DicofolOil Oil Oil Oil Oil

1990Ovicide Test cumulative hatch

Days after treatment1 294a 115a 111a 157a2 700a 375a 149a 320a4 2880a 1834a 1406a 1258a5 4775a 3686a 2207a 1938a6 6348a 5568a 3399a 3462a8 6827a 6820a 3751a 3682a

12-14 6338a 7033a 4169a 3727aEuropean red mitelleafb

19 JuneEggs 1133a 852a 1086a 779a 988aMotiles 478a 333a 567a 290a 320a

28 JuneEggs 1466a 1314a 905a 990a 845aMotiles 81a 61b l4b 08b 18b

2 JulyEggs 877a 670a 286a 339a 325aMotiles 1212a 146b 37b 35b 184b

24 JulyEggs 390a 183a 212a 212a 192aMotiles 564a 284ab 326a 88bc 89c

3 AugustEggs 398ab 310b 544ab 390ab 702aMotiles 145a 55a 255a 157a 63a

8 AugustEggs 1O8b 113b 278a 165ab 215aMotiles 47ab 43a 145bc 155c 66abc

1991Ovicide amp residual larval test

n 524 419 422 517 Hatch 90a 37a 48a 48a Larval mortality 758a 950a 100Oa 1000a

European red miteleafb9 July

1mmatures 621a 1207a 1352a 670aAdults 257a 326a 432a 308a

15 JulyImmatures 132a 44ab 20ab 09bAdults 62a 24ab 18ab 03b

22 July1mmatures 158a 41a 11a 11aAdults 149a 169a 161a 146a

30 JulyImmatures 71a 82a 39a 39aAdults 71a 61a 29a 18a

23 AugustImmatures 06a 03a 05a 06aAdults 03a Ola 02a Ola

Treatment means followed by the same letter ate not significantly different (1990 ovicide test df = 5 6 1 d F = 107 P =04603 2 d F = 126 P = 03889 4 d F = 065 P = 06739 5 d F = 109 P = 04518 6 d F = 097 P = 05034 8 d F = 110P = 04457 12-14 d F = 113 P = 04348 1990 mitesleaf df = 6 8 19 June eggs F = 175 P = 02274 motiles F = 279P = 00909 28 June eggs F = 237 P = 01288 motiles F = 803 P = 00048 2 July eggs F = 140 P = 03218 motiles F =784 P = 00052 24 July eggs F = 275 P = 00932 motiles F = 808 P = 00048 3 August eggs F = 321 P = 00652 motilesF = 088 P = 05513 8 August eggs F = 339 P = 00575 motiles F = 237 P = 01291 1991 mitesleaf df = 69 9 Julyimmatures F = 069 P = 06667 adults F = 047 P = 08132 15 July immatures F = 178 P = 02095 adults F = 147 P =02879 22 July immatures F = 091 P = 05285 adults F = 027 P = 09374 30 July immatures F = 038 P = 08764 adultsF = 073 P = 06376 23 August immatures F = 120 P = 03864 adults F = 034 P = 09002 least significant difference test[SAS Institute 1985]) Counts were transformed before analysis using IOglO(x + 05)

a Treatment dates 1990 oil 21 June and 9 July dicofol 21 and 29 June 1991 oil 12 Julyb Average number of eggs motile forms (adults + immatures) immatures or adults per leaf


References Cited

Chapman P J 1967 Petroleum oils for the controlof orchard pests NY Agric Exp Stn Bull 814Geneva

Chapman P J amp S E Lienk 1966 Effectivenessof oil sprays in European red mite control pp 150-163 In Proceedings 1966 Annual Meeting NewYork State Horticultural Society Rochester

Chapman P J amp G W Pearce 1949 Susceptibilityof winter eggs of the European red mite to petro-leum oils and dinitro compounds J Econ Entomol42 44-47

Davidson N A J E Dibble M L Flint P J Mareramp A Guye 1991 Managing insects and miteswith spray oils Univ Calif Publ 3347 Oakland

Dennehy T J J P Nyrop W H Reissig amp R WWeires 1988 Characterization of resistance todicofol in spider mites (Acari Tetranychidae) fromNew York apple orchards J Econ EntomoI 811551-1561

Gilpatrick J D 1982 Case study 2 Venturia ofpome fruits and Monolinia of stone fruits pp 195-206 In J Dekker amp S G Georgopoulos [eds] Fun-gicide resistance in crop protection Pudoc Wa-geningen

Johnson W T 1985 Horticultural oils J EnvironHortic 3 188-191

Lawson D S amp R W Weires 1991 Managementof European red mite (Acari Tetranychidae) andseveral aphid species on apple with petroleum oils

and an insecticidal soap J Econ EntomoI 841550-1557

Lienk S E C M Watve amp R W Weires 1980Phytophagous and predacious mites on apple inNew York Search 6 (Geneva) 1-14

SAS Institute 1985 SAS users guide statisticsversion 5 ed SAS Institute Cary NC

USDA 1976 United States standards for grades ofapples USDA Food Safety and Quality ServiceWashington DC

US Dept Commerce 1991 Local climatologicaldata Rochester NY airport National Oceanic ampAtmospheric Administration US Dept Com-merce Asheville NC

Welty C W H Reissig T J Dennehy amp R WWeires 1987 Cyhexatin resistance in New Yorkpopulations of European red mite (Acarina Tet-ranychidae) J Econ Entomol 80 230-236

1988 Susceptibility to hexythiazox of eggs and lar-vae of European red mite (Acari Tetranychidae)J Econ Entomol 81 586-592

1989 Activity of clofentezine against European redmite (Acari Tetranychidae) J Econ EntomoI 82197-203

Wilcox W F A M Agnello J Kovach amp W C Stiles1993 1993 pest management recommendationsfor commercial tree-fruit production Cornell Uni-versity Press Ithaca NY

Received for publication 18 December 1992 ac-cepted 3 May 1993


onstrated acceptable control of P ulmi in an ap-ple orchard by applying three widely spacedsprays of different oil formulations at variousrates They also showed the ovicidal efficacy ofthese products against overwintering eggs Morepractical information is needed on the use ofdifferent oil rates during the summer on a pre-ventive basis to maintain a constant low level ofmortality of susceptible mites during a periodwhen populations are a mixture of all life stagesCurrent oil-use recommendations for mite con-trol are based on the assumption that because ofoils mode of action mortality is generally con-fined to the eggs and motile forms are able tosurvive oil applications However this assump-tion has not been investigated systematicallyWelty et al (1988 1989) demonstrated a 9- andll-fold greater susceptibility of summer thanwinter eggs of P ulmi to the ovicides hexythia-zox and clofentezine The objectives of our studywere to determine susceptibility of summer eggsto a narrow-distillation petroleum oil to provide abasis for recommending its use for seasonal con-trol as an alternative to contact materials

Materials and Methods

1989 Laboratory Bioassays Trials were con-ducted January-April using overwintering miteeggs on spur wood collected from commercialorchards the previous November and DecemberAfter storage at 2degC for 30-35 d to assure ade-quate egg chilling the spurs were held in a rear-ing chamber at 25degC and 40 RH under a pho-toperiod of 168 (LD) h to induce hatching thenplaced in close proximity to the foliage of pottedapple seedlings to allow colonization Summereggs were obtained by rearing the hatched mitesto the adult stage on the seedlings and transfer-ring them with a camels-hair brush to the topsurface of an excised leaf (20-25 adult femalesper leaf) set on moistened cotton in a petri dishThe excised leaves were bounded at the edgesby moist cotton barriers to prevent mites fromescaping Dishes were placed in the rearingchamber to allow the adults to lay eggs for 24 hafter which the cotton barriers and all motilemites were removed and the eggs were countedbefore the treatment was administered Serialdilutions of Sunspray Ultra Fine oil (viscosity68 s 50 distillation point 2122degC 10-90distillation range 183degC unsulfonated residue940 Mycogen San Diego CAl in distilled wa-ter were prepared to obtain test solutions of 3 21 075 050 025 010 005 0005 00005000005 and 0000005 but after several pre-liminary trials it was determined that the rangeencompassing nearly complete mortality to totalsurvival was represented by 005 0005 and00005 oil solutions on a volume basis Testleaves containing eggs were dipped for 5 s in200 ml of a test solution that was stirred con-

stantly until just before dipping to prevent phaseseparation For uniformity the three oil solu-tions and a distilled water check were mixed andtested concurrently using eggs from the samecohort with six replicate leaves containing 30-60eggs per treatment After dipping the leaveswere returned to their petri dishes in the rearingchamber The next day a bead of Tree Tangle-foot (Tanglefoot Grand Rapids MI) was placedaround the perimeter of each leaf and the eggswere recounted Leaves were examined forhatched larvae every 1-2 d and ovicidal mortal-ity was determined by comparing the number ofunhatched eggs with the original number of post-treatment eggs

Residual larvicidal effects of the oil solutionswere investigated in a similar manner to parallelan orchard situation where the summer egghatch occurs shortly before the application of anoil spray Adult mites (progeny of the overwin-tered egg generation) were transferred to cotton-bounded excised leaves as described above butthe laying arena was confined to a narrow areaimmediately surrounding the leaf midrib to facil-itate later manipulation After the eggs were laid(usually 3-4 d) and all the adult mites were re-moved this midrib portion of the leaf containingeggs was excised and placed onto the surface ofanother leaf that had been dipped in the oil-testsolution the previous day The same three con-centrations of oil as in the ovicide trials wereused as test solutions Dipped leaves wereplaced on moist cotton in a loosely covered plas-tic crisper and held in the rearing chamber for24 h at 25degC and 40 RH under a photoperiod of168 (LD) h to allow excess solution to run off orevaporate before midribs were placed on themA barrier of Tanglefoot was placed around theleafs perimeter to prevent mites from escapingand 3-4 d were allowed for hatch to occur Theleaf surface was examined and the numbers oflive and dead larvae plus those caught in thetanglefoot and those concealed on the undersur-face of the midrib were recorded and comparedwith the number of unhatched eggs on the mid-rib At the higher oil concentrations large num-bers of larvae were sometimes found under themidrib (not contacting the treated surface) orcaught in the tanglefoot barrier Because suchlarvae could have been exhibiting an escape re-sponse to the oil residue they were excludedfrom any calculations of larvicidal mortalitywhich was determined by comparing the num-ber of dead and live larvae on the treated surface

1990 Laboratory Bioassays Trials were con-ducted January-May using spur wood collectedthe previous fall and all the same ovicidal andlarvicidal assay procedures as in 1989 Serial di-lutions of oil in distilled water were prepared toobtain test solutions of 025 005 0005 00005and 000005 on a volume basis which was aslight expansion of the concentration range used



















Dip Treatments005 594 987 (16) 506 880 (111)0005 568 894 (111) 395 660 (359)00005 550 690 (339) 336 558 (303)0 522 193 (136) 435 02 (06)














100 146 796 (287) 96 (134) 888 (135) 112 (135)075 145 906 (120) 67 (93) 932 (93) 68 (93)050 157 848 (216) 41 (81) 953 (92) 47 (92)025 171 730 (186) 64 (87) 926 (90) 70 (91)Check 168 39 (74) 48 (63) 62 (114) 63 (90)


11 July 1989100 250

0 Chadlt


i 60 1500Z 40 100r

i 20 50



9 August 1989

o Check

ill Half-Season

bull Full-Season

MotilesEggso

400

800

1600

2000

1200


100

o

400

500


-IIICIIJ






-e-Check-+-005 Oil

--- 025 Oil____ 1 Oil

520 64 619 75 720 84 820


o

60

liii 50CD


~ 10

o100

liii 80CD

J

lii 60Q

ci 40Zc 20E


10- 8IIICDI 6CDQ

ci 4zcIII 2CD~

0

30- 25IIICD

J20

CDQ

150Z

10cIIICD 5~

0

t520 64 619 75 720 84 820






510 528 616 75 723 811 830

Station Creek 1990




---e- Check~0050i1---- 025 Oil--lOil

~lTT T ~ T1 1



o

50

35- 30bullCD25I

l 20

~ 15

c 10bullCDIE 5

0

i 30

ci 20zc 10

IE

bullbull 40CDI



ParameterTreatment






















Table 3 Conlinued

TreatmentParameter













83089720629

Sodus 1991

69




0 0

20 35



t t 0

520 69 629 720 89 830 520













159




Acknow ledgments


Station Creek 1991

February 1994

10


0

6

5-IIICD4Jbull

8- 3

~ 2cIICDE

0



TreatmentParameter






















References Cited





































Dip Treatments005 594 987 (16) 506 880 (111)0005 568 894 (111) 395 660 (359)00005 550 690 (339) 336 558 (303)0 522 193 (136) 435 02 (06)














100 146 796 (287) 96 (134) 888 (135) 112 (135)075 145 906 (120) 67 (93) 932 (93) 68 (93)050 157 848 (216) 41 (81) 953 (92) 47 (92)025 171 730 (186) 64 (87) 926 (90) 70 (91)Check 168 39 (74) 48 (63) 62 (114) 63 (90)


11 July 1989100 250

0 Chadlt


i 60 1500Z 40 100r

i 20 50



9 August 1989

o Check

ill Half-Season

bull Full-Season

MotilesEggso

400

800

1600

2000

1200


100

o

400

500


-IIICIIJ






-e-Check-+-005 Oil

--- 025 Oil____ 1 Oil

520 64 619 75 720 84 820


o

60

liii 50CD


~ 10

o100

liii 80CD

J

lii 60Q

ci 40Zc 20E


10- 8IIICDI 6CDQ

ci 4zcIII 2CD~

0

30- 25IIICD

J20

CDQ

150Z

10cIIICD 5~

0

t520 64 619 75 720 84 820






510 528 616 75 723 811 830

Station Creek 1990




---e- Check~0050i1---- 025 Oil--lOil

~lTT T ~ T1 1



o

50

35- 30bullCD25I

l 20

~ 15

c 10bullCDIE 5

0

i 30

ci 20zc 10

IE

bullbull 40CDI



ParameterTreatment






















Table 3 Conlinued

TreatmentParameter













83089720629

Sodus 1991

69




0 0

20 35



t t 0

520 69 629 720 89 830 520













159




Acknow ledgments


Station Creek 1991

February 1994

10


0

6

5-IIICD4Jbull

8- 3

~ 2cIICDE

0



TreatmentParameter






















References Cited






























Dip Treatments005 594 987 (16) 506 880 (111)0005 568 894 (111) 395 660 (359)00005 550 690 (339) 336 558 (303)0 522 193 (136) 435 02 (06)














100 146 796 (287) 96 (134) 888 (135) 112 (135)075 145 906 (120) 67 (93) 932 (93) 68 (93)050 157 848 (216) 41 (81) 953 (92) 47 (92)025 171 730 (186) 64 (87) 926 (90) 70 (91)Check 168 39 (74) 48 (63) 62 (114) 63 (90)


11 July 1989100 250

0 Chadlt


i 60 1500Z 40 100r

i 20 50



9 August 1989

o Check

ill Half-Season

bull Full-Season

MotilesEggso

400

800

1600

2000

1200


100

o

400

500


-IIICIIJ






-e-Check-+-005 Oil

--- 025 Oil____ 1 Oil

520 64 619 75 720 84 820


o

60

liii 50CD


~ 10

o100

liii 80CD

J

lii 60Q

ci 40Zc 20E


10- 8IIICDI 6CDQ

ci 4zcIII 2CD~

0

30- 25IIICD

J20

CDQ

150Z

10cIIICD 5~

0

t520 64 619 75 720 84 820






510 528 616 75 723 811 830

Station Creek 1990




---e- Check~0050i1---- 025 Oil--lOil

~lTT T ~ T1 1



o

50

35- 30bullCD25I

l 20

~ 15

c 10bullCDIE 5

0

i 30

ci 20zc 10

IE

bullbull 40CDI



ParameterTreatment






















Table 3 Conlinued

TreatmentParameter













83089720629

Sodus 1991

69




0 0

20 35



t t 0

520 69 629 720 89 830 520













159




Acknow ledgments


Station Creek 1991

February 1994

10


0

6

5-IIICD4Jbull

8- 3

~ 2cIICDE

0



TreatmentParameter






















References Cited























Dip Treatments005 594 987 (16) 506 880 (111)0005 568 894 (111) 395 660 (359)00005 550 690 (339) 336 558 (303)0 522 193 (136) 435 02 (06)














100 146 796 (287) 96 (134) 888 (135) 112 (135)075 145 906 (120) 67 (93) 932 (93) 68 (93)050 157 848 (216) 41 (81) 953 (92) 47 (92)025 171 730 (186) 64 (87) 926 (90) 70 (91)Check 168 39 (74) 48 (63) 62 (114) 63 (90)


11 July 1989100 250

0 Chadlt


i 60 1500Z 40 100r

i 20 50



9 August 1989

o Check

ill Half-Season

bull Full-Season

MotilesEggso

400

800

1600

2000

1200


100

o

400

500


-IIICIIJ






-e-Check-+-005 Oil

--- 025 Oil____ 1 Oil

520 64 619 75 720 84 820


o

60

liii 50CD


~ 10

o100

liii 80CD

J

lii 60Q

ci 40Zc 20E


10- 8IIICDI 6CDQ

ci 4zcIII 2CD~

0

30- 25IIICD

J20

CDQ

150Z

10cIIICD 5~

0

t520 64 619 75 720 84 820






510 528 616 75 723 811 830

Station Creek 1990




---e- Check~0050i1---- 025 Oil--lOil

~lTT T ~ T1 1



o

50

35- 30bullCD25I

l 20

~ 15

c 10bullCDIE 5

0

i 30

ci 20zc 10

IE

bullbull 40CDI



ParameterTreatment






















Table 3 Conlinued

TreatmentParameter













83089720629

Sodus 1991

69




0 0

20 35



t t 0

520 69 629 720 89 830 520













159




Acknow ledgments


Station Creek 1991

February 1994

10


0

6

5-IIICD4Jbull

8- 3

~ 2cIICDE

0



TreatmentParameter






















References Cited






















100 146 796 (287) 96 (134) 888 (135) 112 (135)075 145 906 (120) 67 (93) 932 (93) 68 (93)050 157 848 (216) 41 (81) 953 (92) 47 (92)025 171 730 (186) 64 (87) 926 (90) 70 (91)Check 168 39 (74) 48 (63) 62 (114) 63 (90)


11 July 1989100 250

0 Chadlt


i 60 1500Z 40 100r

i 20 50



9 August 1989

o Check

ill Half-Season

bull Full-Season

MotilesEggso

400

800

1600

2000

1200


100

o

400

500


-IIICIIJ






-e-Check-+-005 Oil

--- 025 Oil____ 1 Oil

520 64 619 75 720 84 820


o

60

liii 50CD


~ 10

o100

liii 80CD

J

lii 60Q

ci 40Zc 20E


10- 8IIICDI 6CDQ

ci 4zcIII 2CD~

0

30- 25IIICD

J20

CDQ

150Z

10cIIICD 5~

0

t520 64 619 75 720 84 820






510 528 616 75 723 811 830

Station Creek 1990




---e- Check~0050i1---- 025 Oil--lOil

~lTT T ~ T1 1



o

50

35- 30bullCD25I

l 20

~ 15

c 10bullCDIE 5

0

i 30

ci 20zc 10

IE

bullbull 40CDI



ParameterTreatment






















Table 3 Conlinued

TreatmentParameter













83089720629

Sodus 1991

69




0 0

20 35



t t 0

520 69 629 720 89 830 520













159




Acknow ledgments


Station Creek 1991

February 1994

10


0

6

5-IIICD4Jbull

8- 3

~ 2cIICDE

0



TreatmentParameter






















References Cited






















-e-Check-+-005 Oil

--- 025 Oil____ 1 Oil

520 64 619 75 720 84 820


o

60

liii 50CD


~ 10

o100

liii 80CD

J

lii 60Q

ci 40Zc 20E


10- 8IIICDI 6CDQ

ci 4zcIII 2CD~

0

30- 25IIICD

J20

CDQ

150Z

10cIIICD 5~

0

t520 64 619 75 720 84 820






510 528 616 75 723 811 830

Station Creek 1990




---e- Check~0050i1---- 025 Oil--lOil

~lTT T ~ T1 1



o

50

35- 30bullCD25I

l 20

~ 15

c 10bullCDIE 5

0

i 30

ci 20zc 10

IE

bullbull 40CDI



ParameterTreatment






















Table 3 Conlinued

TreatmentParameter













83089720629

Sodus 1991

69




0 0

20 35



t t 0

520 69 629 720 89 830 520













159




Acknow ledgments


Station Creek 1991

February 1994

10


0

6

5-IIICD4Jbull

8- 3

~ 2cIICDE

0



TreatmentParameter






















References Cited




















510 528 616 75 723 811 830

Station Creek 1990




---e- Check~0050i1---- 025 Oil--lOil

~lTT T ~ T1 1



o

50

35- 30bullCD25I

l 20

~ 15

c 10bullCDIE 5

0

i 30

ci 20zc 10

IE

bullbull 40CDI



ParameterTreatment






















Table 3 Conlinued

TreatmentParameter













83089720629

Sodus 1991

69




0 0

20 35



t t 0

520 69 629 720 89 830 520













159




Acknow ledgments


Station Creek 1991

February 1994

10


0

6

5-IIICD4Jbull

8- 3

~ 2cIICDE

0



TreatmentParameter






















References Cited





















ParameterTreatment






















Table 3 Conlinued

TreatmentParameter













83089720629

Sodus 1991

69




0 0

20 35



t t 0

520 69 629 720 89 830 520













159




Acknow ledgments


Station Creek 1991

February 1994

10


0

6

5-IIICD4Jbull

8- 3

~ 2cIICDE

0



TreatmentParameter






















References Cited




















Table 3 Conlinued

TreatmentParameter













83089720629

Sodus 1991

69




0 0

20 35



t t 0

520 69 629 720 89 830 520













159




Acknow ledgments


Station Creek 1991

February 1994

10


0

6

5-IIICD4Jbull

8- 3

~ 2cIICDE

0



TreatmentParameter






















References Cited




















83089720629

Sodus 1991

69




0 0

20 35



t t 0

520 69 629 720 89 830 520













159




Acknow ledgments


Station Creek 1991

February 1994

10


0

6

5-IIICD4Jbull

8- 3

~ 2cIICDE

0



TreatmentParameter






















References Cited

























159




Acknow ledgments


Station Creek 1991

February 1994

10


0

6

5-IIICD4Jbull

8- 3

~ 2cIICDE

0



TreatmentParameter






















References Cited





















TreatmentParameter






















References Cited




















References Cited



















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