Proceedings of the 2007 CPM Short Course and … of the 2007 CPM Short Course and MCPR Trade Show ... Add 1-2 sprays with boscalid mixed with protectant

Proceedings of the2007 CPM Short Course and

MCPR Trade Show

December 4 – 6, 2007

Minneapolis Convention Center

Do not Reproduce or Redistribute Without Written Consent of the Author(s)

W. R. StevensonUW - Madison

Dept of Plant Pathology

W. R. StevensonUW - Madison

Dept of Plant Pathology

Chemical Control Chemical Control –– A critical component of A critical component of many disease management programsmany disease management programs

Chemical controls complement other control measures Chemical controls complement other control measures such as regulatory (quarantines, seed tolerances), cultural such as regulatory (quarantines, seed tolerances), cultural (planting date, rotation, sanitation, irrigation and (planting date, rotation, sanitation, irrigation and nutrition management), host resistance, biological and nutrition management), host resistance, biological and physical methodsphysical methodsChemicals are toxic to pathogens Chemicals are toxic to pathogens ––

May be lethal to pathogen or May be lethal to pathogen or inhibit germination, growth, multiplication of pathogeninhibit germination, growth, multiplication of pathogenSome may affect quality of inoculum (survival, amount)Some may affect quality of inoculum (survival, amount)Some are multipleSome are multiple--site toxicants, others are single sitesite toxicants, others are single site

General groups include General groups include --Fungicides, bactericides, Fungicides, bactericides, nematicidesnematicides, , viricidesviricides, fumigants, fumigants

Chemical Control Chemical Control –– Fungicides Fungicides –– Common UsesCommon Uses

Seed treatmentsSeed treatmentsSoil applications Soil applications –– broadcast, inbroadcast, in--furrowfurrowFoliar sprays, dusts, paints, Foliar sprays, dusts, paints, systemicssystemicsPost harvest sprays, dips, aerosolsPost harvest sprays, dips, aerosolsUse of fungicides requires thorough knowledge of Use of fungicides requires thorough knowledge of host, pathogen and effect of environmenthost, pathogen and effect of environmentGoal is to eliminate the pathogen or at least slow Goal is to eliminate the pathogen or at least slow the rate of disease development the rate of disease development

Examples of fungal diseases:Soybean Asian Rust

Potato Late Blight Sporangia, Zoospores, LesionsPotato Late Blight Sporangia, Zoospores, Lesions

Potato Early BlightPotato Early Blight

Alternaria solani Alternaria solani conidiaconidia

Alternaria solani Alternaria solani conidia germinationconidia germination

Conidia adversely affected by fungicideConidia adversely affected by fungicide

Chemical controls have an important place in Chemical controls have an important place in the history of plant pathologythe history of plant pathology

Sulfur for control of wheat rust Sulfur for control of wheat rust –– 1000 B.C.1000 B.C.Lime sulfur for control of grape downy mildew Lime sulfur for control of grape downy mildew ––early 1800early 1800’’ssBordeaux Mixture (copper sulfate and quicklime Bordeaux Mixture (copper sulfate and quicklime for control of downy for control of downy mildew)(Millardetmildew)(Millardet –– 1883)1883)1932 1932 –– Dawn of organic fungicide eraDawn of organic fungicide era

Chemical Control Chemical Control –– Effect of fungicide on Effect of fungicide on disease developmentdisease development

Early Blight Control - Hancock, 1998Early Blight Control - Hancock, 1998

0

20

40

60

80

100

6/29/1

999

7/6/19

997/1

3/199

97/2

0/199

97/2

7/199

98/3

/1999

8/10/1

999

8/17/1

999

8/24/1

999

Untreated

Bravo/Curzate+Bravo/Bravo+Super TinBravo/ Curzate +BravoQuadris / Curzate +BravoBravo/Curzate+Manzate +BravoSuper Tin + cymoxanil

BAS 500

Quadris (lo) + Bond/Bravo

% Foliage Infection% Foliage Infection

Chemical Control Chemical Control –– Key TermsKey Terms

PreventativePreventative –– prevents establishment of pathogenprevents establishment of pathogenCurativeCurative –– interrupts development of established interrupts development of established infection which is not showing symptomsinfection which is not showing symptomsEradicantEradicant –– interrupts further development of interrupts further development of established infection which is showing symptomsestablished infection which is showing symptomsAntisporulantAntisporulant –– prevents or decreases inoculum prevents or decreases inoculum production without stopping vegetative growthproduction without stopping vegetative growthSystemicSystemic –– movement of fungicide in plant; locally movement of fungicide in plant; locally systemic or systemic or translocatedtranslocated through plant via xylem or through plant via xylem or phloemphloem

Major events in disease development vs. Major events in disease development vs. type of fungicide useful at each eventtype of fungicide useful at each event

Preventative FungicidesPreventative Fungicides

Preventative Preventative ––prevents establishment of an prevents establishment of an infection (sometimes termed protectant)infection (sometimes termed protectant)

Provides chemical barrier to pathogenProvides chemical barrier to pathogenMust be present on plant before infectionMust be present on plant before infectionNot absorbed or Not absorbed or translocatedtranslocated by plantby plantCanCan’’t stop established disease, but slow spreadt stop established disease, but slow spreadComplete coverage is criticalComplete coverage is criticalAffected by environmental variablesAffected by environmental variablesInsurance treatmentInsurance treatment

Curative FungicideCurative Fungicide

Curative Curative –– interrupts development of established interrupts development of established infection which is not showing symptomsinfection which is not showing symptoms

Can cure diseaseCan cure diseaseSystemic (e.g. local, Systemic (e.g. local, translaminartranslaminar, whole plant), whole plant)Coverage not as critical as for preventativesCoverage not as critical as for preventativesKickback activity Kickback activity –– window of opportunitywindow of opportunityOften used after disease appearsOften used after disease appearsResistance in pathogen population more likely than Resistance in pathogen population more likely than with preventativeswith preventatives

Grouping Fungicides By Mode of Action

Currently there are over 40 groups of fungicides Currently there are over 40 groups of fungicides classified by classified by Mode of ActionMode of ActionReference: Reference: www.frac.infowww.frac.info for complete listingfor complete listingAdditional fungicides and Mode of Action groups Additional fungicides and Mode of Action groups added when discovered or identified added when discovered or identified

http://www.frac.info/

Grouping Fungicides By Mode of Action

Dow AgroSciences

Table Legend

Table Cell # common name

Chemical Structure

Major Supplier or Originator

FRAC Group Main Crop/Use

Mode of action LD50 (rat) mg/kg

Main Crop/Use

Efficacy WHO toxicity class

Main Crop/Use

Fungicide GroupingsFungicide Groupings

FRAC Fungicide Grouping:1-37; U, M, P

Modes of Action: A - Y

Elemental sulfur and copperElemental sulfur and copperSulfur used since early Roman timesSulfur used since early Roman timesElemental copper rarely used because of Elemental copper rarely used because of phytotoxicityphytotoxicity

Preventative Fungicide Preventative Fungicide -- InorganicInorganic

Preventative Fungicide Preventative Fungicide -- OrganicOrganic

Multisite inhibitor

Broad spectrum

Used on wide array of crops

Sold as Dithane, Manzate, Penncozeb


Multisite inhibitor

Broad spectrum

Treatment of seed and potato seedpieces

Sold as Captan


Multisite inhibitor

Prevents spore germination

Broad spectrum

Organometallic/fixed copper

Used on wide array of crops

Copper Hydroxide –Sold as Kocide, Champ


Inhibits sulfur-containing enzymes

Used on many crops

Sold as Bravo, Echo, Equus

Curative Fungicide Curative Fungicide -- OrganicOrganic

Inhibition of mitosisSingle site of actionUsed as postharvest treatment

on potatoesResistance risk is highSold as Mertect


Inhibits RNA synthesisPrimarily for control

of OomycetesMultiple sites of actionLow resistance risk Used on potatoes and grapesSold as Curzate


Inhibition of ergosterolsynthesis – Group 3

Single site of actionRisk of resistance - MediumUseful for control of

powdery mildew and rustUsed on cucurbits, mint

and fruitSold as Rally and Nova




powdery mildew and rustUsed on grasses, peanutSold as Folicur




powdery mildew and rustUsed on celery, sweet corn,

corn, cerealsSold alone as Tilt, Stratego as mix with trifloxystrobin, Quilt as mix with azoxystrobin




powdery mildew and rustSold as Domark

Strobilurin Chemistry Strobilurin Chemistry –– Preventative and Preventative and Curative PropertiesCurative Properties

Broad spectrumDisrupts electron transport in

mitochondrial cytochromebc1 complex

SystemicTranslaminar movementHigh risk for resistanceUsed on wide array of cropsSold as Quadris, Heritage,

Abound

Strobilurin Chemistry Strobilurin Chemistry –– Preventative and Preventative and Curative PropertiesCurative Properties

Broad spectrumDisrupts electron transport in

mitochondrial cytochromebc1 complex

SystemicTranslaminar movementHigh risk for resistanceUsed on wide array of cropsSold as Cabrio, Headline

Critical Issues in Use of Fungicides

CoverageCoverageGrowth phases of cropGrowth phases of cropEquipment choice and calibrationEquipment choice and calibrationWeatheringWeatheringWeather variablesWeather variables

TimingTimingComplete protection Complete protection -- start to finishstart to finish

Resistance managementResistance managementSafety Safety –– Environment, applicator, consumerEnvironment, applicator, consumerEconomics of useEconomics of use

Fungicide Resistance

Defined – Inherited change in pathogen’s susceptibility to a fungicideFactors:

Fungicide mode of activity Multi-site e.g. mancozeb, chlorothalonilSingle-site e.g. metalaxyl, members of strobilurin group

PathogenSingle-cycle e.g. White moldMulti-cycle e.g. Late blight, Early blight

Late BlightFoliage LossReduced YieldsStorage Losses

Leaf Infection

Terminal Death

Tuber Decay

Resistance To:metalaxylmefenoxam

WI Case Example – Late Blight

Prior to 1992 – Late blight a periodic problem – 1/5 yrsUS#1 genotype, A1 mating type – metalaxyl sensitiveOutstanding control with Ridomil MZ treatment

Beginning in late 1992, appearance of new genotypes1993 – Appearance of US#8 genotype

Highly aggressive, A2 mating type – metalaxyl insensitiveBy 1996 and thereafter – only US#8 genotypeEffect on Control Tools

Removal of metalaxyl from recommended listAddition of cymoxanil, propamocarb hydrochloride, zoxamideand dimethomorph as late blight productsHeavy dependence on protectant materials – old “standbys”

WI Case Example – Late Blight

The Tragedy of Late Blight1. Loss of valuable chemistry – metalaxyl/mefenoxam because of resistant pathogen genotypes

2. Some growers continued to use ineffective metalaxyl sprays – heavy loss of yield and tuber quality

3. Multimillion $$ loss attributed to late blight when trusted chemicals were ineffective

4. Sudden increase in control costs$50/A control bills ballooned to >$300/AMarket did not compensate for higher control costs

5. A few long established growers quit the potato business when production expenses exceeded returns

Potato Early BlightPotato Early Blight Early BlightDefoliationReduced YieldsTuber Quality Loss

Resistance To:strobilurin group

WI Case Example – Early Blight

Annual appearance on irrigated sandsProgressive loss in foliageAffect on yield and tuber quality

Traditional fungicide program included:Mancozeb, metiram, chlorothalonil, triphenyl tin hydroxide

Arrival of strobilurin class of fungicidesField plot evaluation – best early blight control ever seenExperimental Use Permit – Quadris - 1998 - ~5,000 acres

Outstanding control in split field trialsFull Label (national) – Quadris – 1999Thereafter - Additional strobilurin products released

Amistar, Headline, Gem, Tanos (also contains cymoxanil), Reason, Evito

Comparison of Treatment EfficacyHancock Potato Trial, 1997

AUDPC

0

20

40

60

80

100

7/1 7/8 7/15

7/22

7/29 8/5 8/12

8/19

8/26 9/2

Untreated

Bravo WS Zn 1.5 pt

Quadris, .38 pt/Bravo

Quadris, .76 pt/Bravo

Foliar DiseaseSeverity – Early Blight 0 0.1 0.2 0.3

Earlyblight

Lateblight

Com-bined

UBrQ .38 ptQ .76 pt

Figure 2. Spray programs in 1997 that contained azoxystrobin (Quadris) and chlorothalonil (Bravo) flattened the early blight progress curve in comparison with the untreated check and plots sprayed with chlorothalonil (Bravo) alone.

WI Case Example – Early BlightResistance risk of strobilurin group

Initially considered lowResistance management wording on labelNumber of sprays per season, Seasonal use of products

Resistance began to emergeMost cases, gradual loss of efficacy over yearsOther states, rapid loss of efficacy – 1-2 seasons

Resistance associated with site mutation –Mutation at site F129L in cytochrome b geneDistribution of mutation throughout several statesA 10-20 fold change in sensitivity to strobilurins

Control of early blight with standard protectantsDifficult with standard “old time” protectants

Azoxystrobin Treatment, Hancock Potato Trials, 1997-2005Foliar Disease Severity – Early Blight

0

20

40

60

80

100

6/22

6/28 7/4 7/10

7/16

7/22

7/28 8/3 8/9 8/15

8/21

8/27 9/2

1997 Untreated

1998 Untreated

1999 Untreated

2000 Untreated

2001 Untreated

2002 Untreated

2003 Untreated

2004 Untreated

2005 Untreated

2001

2000

1999

1998

1997

20022002

20032004

2005

Figure 3A. Early blight progress in field trials conducted in 1997-2005 in plots left untreated with fungicide

2001

2000

1999

1998

1997

2002

20032004

2005

Azoxystrobin Treatment, Hancock Potato Trials, 1997-2005Foliar Disease Severity – Early Blight

0

20

40

60

80

100

6/19

6/26 7/3 7/10

7/17

7/24

7/31 8/7 8/14

8/21

8/28 9/4

1997 Q/B

1998 Q/B

1999 Q/B

2000 Q/B

2001 Q/B

2002 Q/B

2003 Q/B

2004 Q/B

2005 Amistar/B

Figure 3B. Early blight progress in field trials conducted in 1997-2005 in plots treated with a seasonal program containing both azoxystrobin (Quadris) (Q) and chlorothalonil (Bravo) (B)

WI Case Example – Early Blight

What Does Resistance To Group 11 Materials Mean For Future Management Of Early Blight?

Introduction of new chemistriesE.g. boscalid (Endura)

Use of multiple chemistries (modes of action) in season-long control programsReduction in number of sprays with any single mode of action, especially newer chemistries with single site activity

Programs using base program of chlorothalonil or mancozebAdd 2 sprays with strobilurin mixed with protectantAdd 1-2 sprays with boscalid mixed with protectantAdd 1-2 sprays with triphenyltin hydroxide mixed with protectant

Cost goal - <$100/A for chemical inputs in disease management program

Treatments Include:

Total Yieldcwt/A

Fungicide Cost($/A)

Gross CropValue ($)

Processing

Net CropValue ($)

Processing

Effect on Crop Value

($ Processing)

Untreated 469 0 1865 1865 0

Bravo Zn 529 65 2081 2016 151

Penncozeb 4F 521 33 1997 1964 99

Echo Zn, Headline, Endura, Dithane DF, Super Tin

622 92 2463 2371 506

$5.50 Value/Cost

Table 1. Comparison of yield, fungicide cost, crop values and benefit to crop value of selected treatments – Russet Burbank - 2005 field trial -Hancock WI Ag Research Station

Resistance Management Doesn’t Cost – It Pays

Treatments Include:

Total Yieldcwt/A

Fungicide Cost($/A)

Gross CropValue ($)

Processing

Net CropValue ($)

Processing

Effect on Crop Value

($ Processing)

Untreated 529 0 2250 2250 0

Bravo Zn 556 62 2389 2327 77

Penncozeb 4F 576 42 2484 2442 192

Echo Zn, Headline, Endura, Dithane DF, Super Tin

618 87 2921 2834 584

$6.71 Value/Cost

Table 1B. Comparison of yield, fungicide cost, crop values and benefit to crop value of selected treatments – Russet Burbank - 2006 field trial - Hancock WI Ag Research Station.

Resistance Management Doesn’t Cost – It Pays

How Can Growers Reduce The Risk Of Pathogen Resistance To Fungicides?

Crop rotation - as long as possible Use cultivars with early blight resistance – fewer inputsUse disease predictive models to time fungicide applications.Scout fields frequently Practice crop hygiene by elimination of primary inoculum sources, e.g. volunteer management, proper cull disposal and alternate host management including weeds.Monitor factors such as soil moisture and crop nutrition to avoid crop stress throughout the season.Follow label guidelines for application of all fungicides. Note label information on resistance management. Look for the Fungicide Group Code on labels and on the fungicidecontainers.

GroupCode

Chemical Group Common Name Product Names Resistance Risk

benzimidazoles thiabendazole Mertect High

thiophanates thiophanate, thiophanate-methyl

Tops, Topsin M High

2 dicarboximides iprodione Rovral M to High

4 phenylamides metalaxylmefenoxam

RidomilRidomil Gold, Ultra Flourish

High

7 carboxamides boscalid flutolanil

EnduraMoncut, Moncoat

Medium

9 anilino-pyrimidines pyrimethanil Scala Medium

11 strobilurinsmethoxy acrylatemethoxy carbamateoximino acetateozazolidine dioneimidazolinonedihydro-dioxazine

azoxystrobinpyraclostrobintrifloxystrobinfamoxadonefenamidonefluoxastrobin

Quadris, Amistar, Quadris Opti HeadlineGemTanos (contains cymoxanil)ReasonEvito

High

12 phenylpyrroles fludioxonil Maxim L to Med

14 aromatic hydrocarbons

quintozene (PCNB) Blocker L to Med

1

Resistance Risk of Fungicide Groups

GroupCode

Chemical Group Common Name Product Names Resistance Risk

15 cinnamic acids dimethomorph Forum L to Med

21 cyanoimidazole cyazofamid Ranman M to High

22 benzamides zoxamide Gavel (also contains mancozeb) L to Med

27 cyanoacetamideoximes

cymoxanil Curzate L to Med

28 carbamates propamocarbhydrochloride

Previcur Flex L to Med

29 2,6-dinitro-anilines fluazinam Omega Low

30 organotin compounds triphenyltinhydroxide

SuperTin L to Med

M M1 – copper copper hydroxide Kocide, Champ Low

M M3–ethylenebisdithiocarbamates(EBDC’s)

mancozebmanebmetiram

Dithane, Manzate, PenncozebManebPolyram

Low

M M4 – phthalimides captan Captan Low

M M5 – phthalonitriles chlorothalonil Bravo, Echo, Equus Low

Resistance Risk of Fungicide Groups

Source: FRAC Website - http://www.frac.info/frac/index.htm

Useful References on the Web

GreenbookGreenbook –– source of labels and MSDS safety source of labels and MSDS safety information on all pesticides used in U.S.information on all pesticides used in U.S.

http://http://www.greenbook.netwww.greenbook.net//

CDMS Ag CDMS Ag ChemChem Information ServicesInformation Serviceshttp:// http:// www.cdms.netwww.cdms.net//

Fungicide Resistance Action Committee (FRAC)Fungicide Resistance Action Committee (FRAC)http://http://www.frac.infowww.frac.info//

University of Wisconsin University of Wisconsin –– Extension PublicationsExtension Publicationshttp://http://www.uwex.eduwww.uwex.edu/topics/publications//topics/publications/

Dow Dow AgroscienceAgroscience –– Periodic Table of FungicidesPeriodic Table of Fungicideshttp://learningstore.uwex.edu/Plantshttp://learningstore.uwex.edu/Plants--C16.aspxC16.aspx

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Proceedings of the 2007 CPM Short Course and … of the 2007 CPM Short Course and MCPR Trade Show ... Add 1-2 sprays with boscalid mixed with protectant