Fungicide sensitivity of Botrytis cinerea causing gray mold of berries in WA Tobin Peever David Dutton Olga Kozhar Dalphy Harteveld Adrian Alcocer Amreen Toor Department of Plant Pathology, WSU Funding: WRRC WBC WSCPR WSCBG
Objectives Estimate sensitivities to five major fungicides used to control Botrytis cinerea in berries in WA Follow up on studies led by Alan Schreiber, Steve Midboe, Chris Clemons and Jim Adaskaveg in 2012 and 2013
Fungicides Tested Elevate (fenhexamid) - inhibitor of sterol biosynthesis FRAC group 17 Rovral (iprodione) inhibitor of osmoregulation FRAC group 2 Switch (cyprodinil) inhibitor of methionine biosynthesis FRAC group 9 Switch (fludioxonil) inhibitor of osmoregulation FRAC group 12 Pristine (boscalid) inhibitor of respiration FRAC group 7
Methods Screen for sensitivity on agar media amended with fungicides at different concentrations Measured growth of each isolate on a single concentration of fungicide relative to a control plate that did not contain fungicide Estimate growth as percent of control Amount of growth is indication of sensitivity to fungicide
Fungicide Sensitivity Assay no fungicide fungicide
Elevate (fenhexamid) sensitivity WA Raspberry Field #1 1.2 Percent Growth of Control 1 0.8 0.6 0.4 0.2 0 0 0.5 5 Less Sensitive Sensitive Fenhexamid concentration (ppm)
Sampling Strategy 2015 Sampled B. cinerea from 6 different hosts including blueberry, raspberry, strawberry, blackberry, wild blackberry, and currants Sampled from 3 counties in WA including Skagit, Whatcom and Island Sampled conventional, organic and untreated fields Host Number of Fields Number of Isolates Blueberry 8 85 Raspberry 8 100 Strawberry 8 100 Blackberry 7 64 Wild Blackberry 4 50 Currant 1 16
Annemiek Schilder Blueberry
Blueberry Sampling Strategy Sampled B. cinerea from 3 blueberry fields in Skagit Co., 1 field in Island Co. and 4 fields in Whatcom Co. in 2015 (n =85) Sampled conventional and low fungicide input fields Field Code County Treatment BC-19-1 Skagit Conventional BC-19-3 Skagit Conventional BC-19-11 Skagit Low Input BC-22-4 Island Low Input BC-19-13 Whatcom Conventional BC-19-6 Whatcom Conventional BC-22-8 Whatcom Conventional BC-19-10 Whatcom Conventional
WA Blueberry Botrytis Fungicide Sensitivity 2015 Proportion Insensitive Isolates Sample Fenhexamid Fludioxonil Iprodione Boscalid Cyprodinil BC-19-1 0.200 0.000 0.000 0.333 0.273 BC-19-3 0.222 0.000 0.000 1.000 0.667 BC-19-11 0.000 0.000 0.000 0.000 0.091 BC-22-4 0.417 0.000 0.000 0.182 0.083 BC-19-13 0.714 0.000 0.000 0.714 0.778 BC-19-6 0.583 0.000 0.000 1.000 0.917 BC-22-8 0.000 0.000 0.000 0.375 0.636 BC-19-10 0.667 0.000 0.000 0.833 0.667
WA Blueberry Botrytis 2015 - Fungicide Sensitivity Fenhexamid Boscalid Cyprodinil 1 0.8 0.6 0.4 0.2 0 1.0 0.8 0.6 0.4 0.2 0.0 1.0 0.8 0.6 0.4 0.2 0.0 Field 1 Field 2 Field 3 Field 4 Field 5 Field 6 Field 7 Field 8 Skagit Whatcom
Pete Bristow Raspberry
Raspberry Sampling Strategy Sampled B. cinerea from 2 raspberry fields in Skagit Co., and 6 fields in Whatcom Co. in 2015 (n =100) Sampled conventional and low input fields Field Code County Treatment BC-21-1 Skagit Low Input BC-21-5 Skagit Conventional BC-18-1 Whatcom Conventional BC-21-7 Whatcom Conventional BC-21-9 Whatcom Conventional BC-21-10 Whatcom Conventional BC-21-13 Whatcom Conventional BC-21-15 Whatcom Conventional
WA Raspberry Botrytis Fungicide Sensitivity 2015 Proportion Insensitive Isolates Sample Fenhexamid Fludioxonil Iprodione Boscalid Cyprodinil BC-21-1 0.000 0.000 0.000 0.000 0.071 BC-21-5 0.429 0.000 0.000 0.285 0.214 BC-18-1 0.692 0.000 0.000 0.846 0.769 BC-21-7 0.692 0.000 0.000 0.923 0.846 BC-21-9 0.429 0.000 0.000 0.429 0.428 BC-21-10 1.000 0.000 0.000 0.857 1.000 BC-21-13 0.538 0.000 0.000 0.231 1.000 BC-21-15 0.615 0.000 0.000 0.538 0.333
Botrytis Fungicide Sensitivity WA Raspberry 2015 Fenhexamid Boscalid Cyprodinil 1.00 0.80 0.60 0.40 0.20 0.00 1.00 0.80 0.60 0.40 0.20 0.00 1.00 0.80 0.60 0.40 0.20 0.00 Field 2 Field 3 Field 1 Field 4 Field 5 Field 6 Field 7 Field 8 Skagit Whatcom
Strawberry
Strawberry Sampling Strategy Sampled B. cinerea from 4 strawberry fields in Skagit Co., 1 field in Island Co. and 3 fields in Whatcom Co. in 2015 (n =100) Sampled conventional, low input, organic and untreated fields Field Code County Treatment BC-20-1 Skagit Conventional BC-20-2 Skagit Untreated BC-20-3 Skagit Low Input BC-20-4 Skagit Organic BC-20-7 Island Conventional BC-20-8 Whatcom Conventional BC-20-9 Whatcom Conventional BC-20-11 Whatcom Untreated
WA Strawberry Botrytis Fungicide Sensitivity 2015 Proportion Insensitive Isolates Sample Fenhexamid Fludioxonil Iprodione Boscalid Cyprodinil BC-20-1 0.091 0.000 0.000 0.091 0.083 BC-20-2 0.143 0.000 0.000 0.000 0.000 BC-20-3 0.167 0.000 0.000 0.583 0.417 BC-20-4 0.000 0.000 0.000 0.000 0.000 BC-20-7 0.154 0.000 0.000 0.077 0.000 BC-20-8 0.500 0.000 0.000 0.333 0.250 BC-20-9 0.643 0.000 0.000 0.385 0.200 BC-20-11 0.667 0.000 0.000 0.250 0.167
Botrytis Fungicide Sensitivity WA Strawberry 2015 1.00 0.80 Fenhexamid 0.60 0.40 0.20 0.00 1.00 0.80 Boscalid 0.60 0.40 0.20 0.00 1.00 0.80 Cyprodinil 0.60 0.40 0.20 0.00 Field 1 Field 2 Field 3 Field4 Field 5 Field 6 Field 7 Field 8 Skagit Whatcom
WA Botrytis Fungicide Sensitivity Across All Berry Crops 1.000 Proportion Insensitive Isolates 0.800 0.600 0.400 0.200 fenhexamid boscalid cyprodinil 0.000 blueberry 2015 blackberry 2015 strawberry 2015 raspberry 2015 raspberry 2014
Adjacent Raspberry, Strawberry, Blueberry and Blackberry Fields 1 Proportion Insensitive Isolates 0.8 0.6 0.4 0.2 0 1 0.8 0.6 0.4 0.2 0 1 0.8 0.6 0.4 0.2 0 Fenhexamid Boscalid Cyprodinil Strawberry BC-20-9 Blueberry BC-19-13 Blackberry BC-23-3 Strawberry BC-20-7 Blackberry BC-23-4 Raspberry BC-1-1 Blackberry BC-23-2
Conclusions No evidence of highly insensitive isolates to fludioxonil or iprodione in WA Widespread insensitivity to Elevate (fenhexamid) in raspberry need to monitor to determine if frequencies decline Clear correlation of fungicide use history to fungicide insensitivity selection for insensitivity Insensitivity detected to 3 of 5 site-specific fungicides used to control Botrytis in berries some fields have high levels to all 3
Conclusions (cont d) Frequencies of isolates highly insensitive to Rovral (iprodione) have declined since late 1990 s fungicide can be used again but carefully Large variation in frequencies of insensitivity from field to field for a given crop and also among berry crops even adjacent fields Botrytis populations appear to be quite local (ie. no long-distance movement among fields, between adjacent berry crops) Many fields have high levels of insensitivity to cyprodinil, one component of Switch. Does this mean that fludioxonil is masking insensitivity to cyprodinil?
Recommendations Continue to avoid use of Elevate (fenhexamid) monitor populations to determine if resistant isolates decline in frequency Reduce selection pressure reduce number of sprays from each FRAC group to a minimum Reduce reliance on site-specific fungicides by alternating or mixing with non site-specific fungicides like Captan and using other disease control measures when available Use fungicides only when needed timing of application related to infection rather than calendar
Fenhexamid EC 50 WA Raspberry Isolates Sensitive = 0.62 ppm Less-Sensitive = 41.96 ppm 0 10 20 30 40 50 60 70 80 EC 50 (ppm)
Boscalid EC 50 WA Raspberry Isolates Sensitive = 1.89 ppm Less-Sensitive = 197.64 ppm 0 100 200 300 400 500 600 EC 50 (ppm)
Cyprodinil EC 50 WA Raspberry Isolates Sensitive = 0.17 ppm Less-Sensitive = 12.73 ppm 0 5 10 15 20 25 30 EC 50 (ppm)
Iprodione EC 50 WA Raspberry Isolates Sensitive = 0.59 ppm Less-Sensitive = 3.43 ppm 0 1 2 3 4 5 6 7 8 9 10 EC 50 (ppm)
EC 50 Estimates WA Raspberry Isolates Fungicide EC50 Sensitive EC50 Less-Sensitive Fenhexamid 0.62 41.96 Iprodione 0.59 3.43 Boscalid 1.89 197.64 Fludioxonil 0.18 ---- Cyprodinil 0.17 12.73
Summarizing Fungicide Sensitivity in Botrytis cinerea 50 Decreasing sensitivity to the fungicide Number of Isolates 40 30 20 10 0 0.1 0.3 0.5 0.7 0.9 1.1 Percent Growth of Control
WA Raspberry Botrytis 2014 Fungicide Sensitivity Proportion Insensitive Isolates Sample Fenhexamid Fludioxonil Iprodione Boscalid Cyprodinil BC-1-1 0.462 0.000 0.000 0.000 0.167 BC-1-2 0.417 0.000 0.000 0.000 0.000 BC-1-3 0.846 0.000 0.000 0.000 0.000 BC-1-4 0.636 0.000 0.000 0.300 0.273 BC-1-5 0.900 0.000 0.000 0.417 0.273 BC-1-6 1.000 0.000 0.000 0.100 0.100 BC-1-7 0.909 0.000 0.000 0.091 0.000 BC-1-8 1.000 0.000 0.000 0.111 0.182 BC-1-9 0.333 0.000 0.000 0.000 0.000 BC-1-10 0.000 0.000 0.000 0.000 0.000 BC-1-11 0.667 0.000 0.000 0.364 0.375 BC-1-12 0.455 0.000 0.000 0.455 0.333 BC-1-13 1.000 0.000 0.000 0.000 0.000
Botrytis Fungicide Sensitivity WA Raspberry 2014 1.00 Fenhexamid 0.80 0.60 0.40 0.20 0.00 1.00 Boscalid 0.80 0.60 0.40 Cyprodinil 0.20 0.00 1.00 0.80 0.60 0.40 0.20 0.00 Field 1 Field 2 Field 3 Field 4 Field 5 Field 6 Field 7 Field 8 Field 9 Field 10 Field 11 Field 12 Field 13 Whatcom
Comparison of Fungicide Insensitivities Strawberry vs. Raspberry Proportion Insensitive Isolates Sample Fenhexamid Fludioxonil Iprodione Boscalid Cyprodinil Raspberry 2014 Strawberry 2015 0.72 0.00 0.00 0.14 0.13 0.33 0.00 0.00 0.22 0.14
WA versus BC Botrytis Fungicide Sensitivity 1.0 Proportion Insensitive Isolates 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 fenhexamid boscalid cyprodinil 0.0 WA BC WA BC WA raspberry 2014 BC raspberry 2014 WA blueberry 2015 BC blueberry 2014 Raspberry Blueberry
Blackberry Blackberry
Blackberry Sampling Strategy Sampled B. cinerea from 3 blackberry fields in Skagit Co., 1 field in Island Co. and 2 fields in Whatcom Co. in 2015 (n =64) Sampled conventional, organic and low fungicide input fields Field Code County Treatment BC-23-1A Skagit Conventional BC-23-1B Skagit Conventional BC-23-7 Skagit Organic BC-23-4 Island Low Input BC-23-2 Whatcom Conventional BC-23-3 Whatcom Conventional
WA Blackberry Botrytis Fungicide Sensitivity 2015 Proportion Insensitive Isolates Sample Fenhexamid Fludioxonil Iprodione Boscalid Cyprodinil BC-23-1A 0.900 0.000 0.000 1.000 0.900 BC-23-1B 0.600 0.000 0.000 0.900 0.800 BC-23-7 0.167 0.000 0.000 0.167 0.167 BC-23-4 0.200 0.000 0.000 0.100 0.100 BC-23-2 0.333 0.000 0.000 0.714 0.667 BC-23-3 0.700 0.000 0.000 1.000 0.700
WA Blackberry Botrytis - Fungicide Sensitivity Fenhexamid Boscalid Cyprodinil 1.00 0.80 0.60 0.40 0.20 0.00 1.00 0.80 0.60 0.40 0.20 0.00 1.00 0.80 0.60 0.40 0.20 0.00 Field 4 Field 3 Field 5 Field 6 Field 2 Field 1 Field 4 Field 3 Field 5 Field 6 Field 2 Field 1 Field 1 Field 2 Field 6 Field 5 Field 3 Field 4 Skagit Whatcom
Repeated Sampling of Cane Isolates from Single Raspberry Field Proportion Insensitive Isolates Year Fenhexamid Fludioxonil Iprodione Boscalid Cyprodinil 2014 1.00 0.00 0.00 0.17 0.10 2015 0.69 0.00 0.00 0.85 0.77