Cross resistance of new FRAC 7 Fungicides for Control of Gray Mold in Berries in PNW

Transcription

1 Cross resistance of new FRAC 7 Fungicides for Control of Gray Mold in Berries in PNW Tobin Peever David Dutton Dalphy Harteveld Olga Kozhar Dept of Plant Pathology Washington State University Siva Sabaratnum BC Ministry of Ag Funding: WRRC WBC WSCPR WSCBG BC Blueberry Council

2 Grey Mold Disease Cycle 8 2C Modified from Cornell University

3 Fungicides Tested Elevate (fenhexamid) - inhibitor of sterol biosynthesis FRAC group 7 Rovral (iprodione) inhibitor of osmoregulation FRAC group 2 Switch (cyprodinil) inhibitor of methionine biosynthesis FRAC group 9 Switch (fludioxonil) inhibitor of osmoregulation FRAC group 2 Pristine (boscalid) inhibitor of respiration FRAC group 7

4 Fungicide Sensitivity Assay no fungicide fungicide

5 Iprodione Sensitivity WA Blueberry 26 Proportion Growth of Control Isolate

6 Spore Germination - Field Rate Iprodione Treat plates with field rates of iprodione Streak spores of isolates with different sensitivity. Percent growth of control on 3 ppm iprodione.

7 Botrytis spore germination Field Rates of Switch, Cyprodinil, Fludioxonil Percent Germination 8 hours Isolate Fludioxonil Cyprodinil Switch BC--8-3 BC--5-9 BC--6-5 BC BC BC BC BC---2 BC BC-8--3 BC BC BC BC-2--7 BC BC-6--3 BC BC-8--8 BC BC BC BC BC BC--2-5 BC-6-2- BC--9-3 BC--4-5

8 Boscalid Resistance in PNW Raspberry 26. Proportion of Isolates. Washington Raspberry 6% Resistant British Columbia Raspberry 75% Resistant Field

9 Fungicides Tested X X X Elevate (fenhexamid) - inhibitor of sterol biosynthesis FRAC group 7 Rovral (iprodione) inhibitor of osmoregulation FRAC group 2 Switch (cyprodinil) inhibitor of methionine biosynthesis FRAC group 9 Switch (fludioxonil) inhibitor of osmoregulation FRAC group 2 X? Pristine (boscalid) inhibitor of respiration FRAC group 7

10 FRAC Group 7 Fungicides (SDHIs) Inhibit succinate dehydrogenase in the inner membrane of the mitochondrion ( Boscalid widespread resistance in PNW average freq. ~ 7% isofetamid Kenja, ISK pydiflumetofen Adepidyn, Syngenta fluopyram Luna, Bayer penthiopyrad Fontelis, Dupont fluxapyroxad Xemium, BASF These new SDHI fungicides are claimed by their manufacturers to control some boscalid-resistant strains of Botrytis cinerea Molecular mechanism of boscalid resistance is known mutations in subunits B, C, and D of succinate dehydrogenase abolish binding Efficacy of these new fungicides will depend on which mutations are present in PNW

11 Cross-Resistance Resistance to Fungicide B Fungicides in the same FRAC group are generally cross-resistant Resistance to Fungicide A

12 Group 7 EC 5 Values in PNW 2 boscalid Number of Isolates Cut-off value for boscalid resistance (approx. > 8- ppm) adepidyn isofetamid fluopyram penthiopyrad fluxapyroxad EC 5

13 Cross resistance to boscalid in PNW Botrytis fluopyram isofetamid adepidyn penthiopyrad fluxapyroxad... boscalid 2 boscalid

14 Activity of new SDHI-fungicides against boscalidresistant strains of Botrytis cinerea isofetamid fluopyram boscalid fluxapyroxad penthiopyrad sensitive S S S S S H272R S S R S S H272Y S S R MR R H272V - *MR R **R **R N23I S MR R MR R P225F R R R R R H272L R R R MR R S: Sensitive MR: Moderately Resistant R: Resistant Data provided by Chris Gee, ISK Biosciences, *Angelini et al. 24, **George Musson, Bayer

15 Boscalid resistance mutations SdhB gene 22 isolates with different boscalid insensitivities: resistant to boscalid sensitive to boscalid sensitive resistant resistant resistant reference Codon 272 Frequencies 45% (5) - H272Y 46% (5) - H272R 9% () - H272V

16 Boscalid resistance mutations - WA berry crops 27 Field ID Crop # boscalid resistant H272Y H272R Other raspberry raspberry raspberry raspberry raspberry raspberry : strawberry strawberry strawberry 3 2 2:. 24 blueberry 3 3 2:. 2 blueberry blueberry blueberry blackberry blackberry blackberry blackberry blackberry currants 4 3 Total Percent 62 27

17 Summary New FRAC7 fungicides look promising for Botrytis control in PNW need to be used with care! Resistance may already exist Two functional groups fluopyram/isofetamid and adepidyn/ penthiopyrad/fluxapyroxad Resistance to boscalid in PNW populations of Botrytis cinerea is conferred by 3 mutations in codon 272 of SdhB gene H272R, H272Y, H272V H272Y (6%) and H272R (3%) are most frequent boscalid-resistance mutations in PNW appear to be controllable by some of the new Group 7 fungicides Mutation H272V appears to confer cross resistance to all new FRAC 7 fungicides need to follow this mutation carefully in PNW

18

19 Boscalid Resistance in PNW Rasbpberry Blueberry Percent Resistant Washington British Columbia

20 5 5 Boscalid 5ppm Sensitivity to Group 7 Fungicides in PNW Discriminatory Doses 5 Fluopyram 5ppm 5 Adepidyn ppm Frequency Isofetamid ppm 5 Penthiopyrad 5ppm Proportion Growth of Control

21 New SDHIs appear to fall into 2 functional types isofetamid penthiopyrad fluopyram H272Y mutation adepidyn H272V mutation

22 Cross resistance to boscalid in PNW Botrytis fluopyram isofetamid boscalid boscalid adepidyn boscalid penthiopyrad boscalid

23 Next Steps Screen a larger number of B. cinerea isolates from different berry crops in WA, BC, OR for sensitivity to adepidyn, isofetamid, fluopyram, penthiopyrad Single conc n screening adepidyn and isofetamid ( ppm), fluopyram and penthiopyrad (5 ppm) ~ population mean EC 5 Relate in vitro sensitivity to ability of field rates to protect fruit from most insensitive isolates establish a threshold for resistance Characterize mutations in SDH gene among PNW isolates with different sensitivity phenotypes to boscalid and other Group 7 fungcides Field trials of new Group 7 fungicides to test efficacy and support registration on berries

24 Cross resistance to boscalid in PNW Botrytis adepidyn boscalid penthiopyrad boscalid fluxapyroxad... boscalid

25 Cross resistance to boscalid in PNW Botrytis fluopyram isofetamid boscalid boscalid

26 Classic Cross Resistance within a FRAC Group Correlation of sensitivities to cyprodinil and pyrimethanil AP fungicides (FRAC Group 9) PNW Botrytis cinerea.2 ppm pyrimethanil ppm cyprodinil

27 WA Botrytis Fungicide Resistance Across All Berry Crops. Proportion Resistant Isolates. fenhexami d boscalid cyprodinil blueberry 25 blackberry 25 strawberry 25 raspberry 25 raspberry 24

28 Sensitivity to new Group 7 fungicides and boscalidresistance mutations in PNW isolate county, crop Year boscalid EC5 boscalid 5 ppm 5 ppm fluopyram ppm isofetamid ppm adepidyn 5 ppm penthiopyrad BC Skagit, strawberry 25 ND H272 BC-2--5 Skagit, raspberry 25 ND (8.4) 5 (.9).34 (.3).39 (2.) H272 BC Whatcom, raspberry 25 ND.5.53 (8.5).53 (2.5).39 (.).53 (7.8) H272 BC---2 Whatcom, raspberry H272 BC--2-7 Whatcom, raspberry H272 BC--7-5 Whatcom, raspberry H272 BC-5--2 BC, Raspberry H272 BC BC, Raspberry H272 BC BC, Blueberry H272 BC BC, Raspberry H272 BC BC, Raspberry 25 ND.54 9 (4.).55 (2.) (.5) ND H272 SDHB mutation BC--6-8 Whatcom, raspberry (3.3) H272R BC--- Whatcom, raspberry (.7) 2.39 H272R BC-5-- BC, Raspberry H272R BC BC, Blueberry H272R BC-26-- BC, Blueberry 25 ND.92 6 (3.3).54 (.2).52 (2.7) 6 (3.) H272R BC--4-8 Whatcom, raspberry H272Y BC Skagit,Strawberry 25 ND H272Y BC Whatcom, raspberry 25 ND H272Y BC BC, Raspberry H272Y BC BC, Raspberry 25 ND (.7) 7 (.4).53 (2.) 2 H272Y BC-23-B-5 Skagit, blackberry 25 ND H272V

29 New Group 7 Fungicide EC 5 Values PNW Botrytis Frequency Cut-off value for boscalid resistance (approx. > 8- ppm) boscalid adepidyn isofetamid fluopyram penthiopyrad EC 5

30 Iprodione Sensitivity WA Blueberry 26 Proportion Growth of Control Isolate

31 Fruit Protection Assay Field Rate of Cyprodinil UNINOCULATED DAY 23 4 BC % BC % BC % NOT PROTECTED PROTECTED

32 Activity of new SDHI-fungicides against boscalid-resistant strains of Botrytis cinerea isofetamid fluopyram boscalid fluxapyroxad penthiopyrad sensitive S S S S S H272R S S R S S H272Y S S R MR R H272V - *MR R **R **R N23I S MR R MR R P225F R R R R R H272L R R R MR R S: Sensitive MR: Moderately Resistant R: Resistant Data provided by Chris Gee, ISK Biosciences *Angelini et al. 24, **George Musson, Bayer

33 Boscalid Resistance in PNW Blueberry 26. Proportion of Isolates. Washington Blueberry 86% Resistant British Columbia Blueberry 65% Resistant Field

34 Frequencies of Fungicide Resistance PNW Botrytis Populations 24-5 Fenhexamid Boscalid Cyprodinil

35 Multiple Fungicide Resistance in Botrytis cinerea WA Raspberry 25 Proportion Resistant Isolates Fenhex/Bosc/Cypro Bosc/Cypro Fenhex/Cypro Fenhex/Boscalid Cypro Bosc Fenhex Field

36 Can Fungicide Use History Predict Resistance?.2. Fenhexamid Frequency of Resistant Isolates Boscalid Cyprodinil Average Number of Sprays per Year

37 Conclusions No evidence of highly insensitive isolates to fludioxonil or iprodione in PNW to date Resistance detected to 3 of 5 site-specific fungicides used to control Botrytis in berries some fields have high levels to all three Widespread resistance to fenhexamid, boscalid, and cyprodinil in all berries need to reduce selection Large variation in frequencies of resistance from field to field are Botrytis populations local? Clear correlation of fungicide use history to fungicide insensitivity selection for resistance Frequencies of multiple fungicide resistance 3-4% - selection by each fungicide may not be independent Reduce selection by reducing fungicide use AND using integrated disease control

38 Fungicide Resistance Management Monitor fields to determine current status of resistance each field is likely different Reduce selection pressure reduce number of sprays from each FRAC group to minimum Alternate high-risk fungicides from each FRAC group through season Pay attention to mode of action and FRAC group rather than tradename or chemical name Reduce reliance on site-specific fungicides by mixing with non site-specific fungicides like Captan Use alternative disease control measures whenever possible Use fungicides only when needed timing of application related to infection events rather than calendar

39 PNW Botrytis Sampling Year Location Host Fields Isolates 24 WA Raspberry 3 2 BC Raspberry 9 BC Blueberry WA Blueberry 8 85 WA Raspberry 3 WA Strawberry 8 WA Blackberry 7 64 WA Wild Blackberry 4 5 WA Currant 6 BC Raspberry 3 29 BC Blueberry WA Raspberry 6 9 WA Blueberry 8 2 WA Blackberry 2 3 BC Raspberry 7 5 BC Blueberry 8 8

40 Non-Fungicidal Gray Mold Control Promote air circulation and drying of plant tissue by maintaining an open plant canopy, burning back early primocanes and controlling weeds Optimize irrigation to prevent plants from being wet for extended periods of time Minimize sources of inoculum like dead leaves and canes, prunings

41 Gray Mold Control Recommendations BC Berries Production Guide Begin fruit rot control sprays once flowers start to open (% bloom). Repeat weekly or as necessary during periods of wet weather Apply control sprays for fruit rot, as required Apply fruit rot sprays, as necessary. If rain occurs during harvest, apply a fungicide immediately after a harvest to prevent the development of "spot mould" on the fruit Do we know when is necessary? No, not really! Control of grey mold currently relies on calendar-based spray schedules Can we lower selection pressure for fungicide resistance by reducing number of sprays?