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
Grey Mold Disease Cycle 8 hrs @ 2C Modified from Cornell University
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
Fungicide Sensitivity Assay no fungicide fungicide
Iprodione Sensitivity WA Blueberry 26 Proportion Growth of Control.9.7.5.3. 2 4 6 8 2 4 6 8 Isolate
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.
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-2-3-6 BC-37-7-4 BC-26-2-9 BC-5-9-4 BC---2 BC-37-7-2 BC-8--3 BC-5-7-2 BC-26-9-9 BC-36-9-4 BC-2--7 BC-6-3-6 BC-6--3 BC-36-2-5 BC-8--8 BC-6-2-3 BC-37-3-4 BC-36-4-4 BC-36-3-4 BC-37-6-3 BC--2-5 BC-6-2- BC--9-3 BC--4-5
Boscalid Resistance in PNW Raspberry 26. Proportion of Isolates. Washington Raspberry 6% Resistant British Columbia Raspberry 75% Resistant Field
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
FRAC Group 7 Fungicides (SDHIs) Inhibit succinate dehydrogenase in the inner membrane of the mitochondrion (http://www.frac.info/working-group/sdhi-fungicides) 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
Cross-Resistance Resistance to Fungicide B Fungicides in the same FRAC group are generally cross-resistant Resistance to Fungicide A
Group 7 EC 5 Values in PNW 2 boscalid Number of Isolates 8 6 4 Cut-off value for boscalid resistance (approx. > 8- ppm) adepidyn isofetamid fluopyram penthiopyrad fluxapyroxad 2 54 5 46 42 38 34 3 26 22 8 4 6 2 9 7 5 3 EC 5
Cross resistance to boscalid in PNW Botrytis fluopyram isofetamid adepidyn penthiopyrad fluxapyroxad... boscalid 2 boscalid
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
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
Boscalid resistance mutations - WA berry crops 27 Field ID Crop # boscalid resistant H272Y H272R Other 32. 8 raspberry 2 7 4 32. 6 raspberry 3 2 32. 7 raspberry 4 2 2 32. 2 raspberry 9 7 2 32. 26 raspberry 5 3 32. 22 raspberry 7 5 3. : strawberry 4 3 3. 9 strawberry 4 3 3. 22 strawberry 3 2 2:. 24 blueberry 3 3 2:. 2 blueberry 4 6 33. 5 blueberry 3 33. 9 blueberry 3 2 34. 5 blackberry 34. 6 blackberry 2 34. 7 blackberry 2 2 34. 8 blackberry 34. 2 blackberry 4 2 2 35. 2 currants 4 3 Total 4 65 28 Percent 62 27
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
Boscalid Resistance in PNW 24-26 8 Rasbpberry Blueberry Percent Resistant 6 4 2 8 6 4 2 Washington British Columbia 24 25 26
5 5 Boscalid 5ppm Sensitivity to Group 7 Fungicides in PNW Discriminatory Doses 5 Fluopyram 5ppm 5 Adepidyn ppm Frequency 5 5 5 Isofetamid ppm 5 Penthiopyrad 5ppm 5 5..9.7.5.3...9.7.5.3. Proportion Growth of Control
New SDHIs appear to fall into 2 functional types isofetamid penthiopyrad.9.7.5.3..9.7.5.3. fluopyram H272Y mutation adepidyn H272V mutation
Cross resistance to boscalid in PNW Botrytis fluopyram isofetamid boscalid boscalid adepidyn boscalid penthiopyrad boscalid
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
Cross resistance to boscalid in PNW Botrytis adepidyn boscalid penthiopyrad boscalid fluxapyroxad... boscalid
Cross resistance to boscalid in PNW Botrytis fluopyram isofetamid boscalid boscalid
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.....2 ppm cyprodinil
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
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-2-4-33 Skagit, strawberry 25 ND 5.35 5 7 H272 BC-2--5 Skagit, raspberry 25 ND.39.57 (8.4) 5 (.9).34 (.3).39 (2.) H272 BC-2-3-3 Whatcom, raspberry 25 ND.5.53 (8.5).53 (2.5).39 (.).53 (7.8) H272 BC---2 Whatcom, raspberry 24. 3 9 2.33 H272 BC--2-7 Whatcom, raspberry 24 4..3 2 6 5 9 H272 BC--7-5 Whatcom, raspberry 24 3. 2 8.54 3.34 H272 BC-5--2 BC, Raspberry 24.36 4.52 9.33 H272 BC-5-7-4 BC, Raspberry 24.7.5 9 9.32 H272 BC-6-9-7 BC, Blueberry 24 9 2.5 4 H272 BC-5-3-4 BC, Raspberry 24 6.4.39 2 2 3.3 H272 BC-25-4-4 BC, Raspberry 25 ND.54 9 (4.).55 (2.) (.5) ND H272 SDHB mutation BC--6-8 Whatcom, raspberry 24.5 4 6 (3.3) 8 4 4 H272R BC--- Whatcom, raspberry 24 35..92.5.5 (.7) 2.39 H272R BC-5-- BC, Raspberry 24 228.9 6.38 2 H272R BC-6-3-4 BC, Blueberry 24 63.5.75.5.55 5 H272R BC-26-- BC, Blueberry 25 ND.92 6 (3.3).54 (.2).52 (2.7) 6 (3.) H272R BC--4-8 Whatcom, raspberry 24 8. 4 6 9 5.58 H272Y BC-2-3-2 Skagit,Strawberry 25 ND 4.7.9.77.73 H272Y BC-2-5-5 Whatcom, raspberry 25 ND 7.52.54 H272Y BC-5-5-5 BC, Raspberry 24 533.6 8.33.33.59 H272Y BC-25--3 BC, Raspberry 25 ND.97.38 (.7) 7 (.4).53 (2.) 2 H272Y BC-23-B-5 Skagit, blackberry 25 ND.94.75.77 4 4 H272V
New Group 7 Fungicide EC 5 Values PNW Botrytis Frequency 2 8 6 4 2 Cut-off value for boscalid resistance (approx. > 8- ppm) boscalid adepidyn isofetamid fluopyram penthiopyrad 54 52 5 48 46 44 42 4 38 36 34 32 3 28 26 24 22 2 8 6 4 2 8 6 4 2 9 8 7 6 5 4 3 2 EC 5
Iprodione Sensitivity WA Blueberry 26 Proportion Growth of Control.9.7.5.3. 2 4 6 8 2 4 6 8 Isolate
Fruit Protection Assay Field Rate of Cyprodinil UNINOCULATED DAY 23 4 BC-27--5 4% BC-9-6-2 76% BC-26-6- 95% NOT PROTECTED PROTECTED
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
Boscalid Resistance in PNW Blueberry 26. Proportion of Isolates. Washington Blueberry 86% Resistant British Columbia Blueberry 65% Resistant Field
Frequencies of Fungicide Resistance PNW Botrytis Populations 24-5 Fenhexamid Boscalid Cyprodinil
Multiple Fungicide Resistance in Botrytis cinerea WA Raspberry 25 Proportion Resistant Isolates.9.7.5.3. Fenhex/Bosc/Cypro Bosc/Cypro Fenhex/Cypro Fenhex/Boscalid Cypro Bosc Fenhex Field
Can Fungicide Use History Predict Resistance?.2. Fenhexamid Frequency of Resistant Isolates..2...2. 2 3 4 2 3 4 Boscalid Cyprodinil. 2 3 4 Average Number of Sprays per Year
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
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
PNW Botrytis Sampling 24-26 Year Location Host Fields Isolates 24 WA Raspberry 3 2 BC Raspberry 9 BC Blueberry 5 8 25 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 5 36 26 WA Raspberry 6 9 WA Blueberry 8 2 WA Blackberry 2 3 BC Raspberry 7 5 BC Blueberry 8 8
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
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?