CHARACTERIZATION OF BOTRYTIS CINEREA RESISTANCE TO FUNGICIDES IN CALIFORNIA STRAWBERRIES SCOTT COSSEBOOM

Transcription

1 CHARACTERIZATION OF BOTRYTIS CINEREA RESISTANCE TO FUNGICIDES IN CALIFORNIA STRAWBERRIES SCOTT COSSEBOOM

2 Outline Introduction Fungicide resistance screening Fungicide use survey Species Identification Field Trial

3 Show Where where strawberries 1 are are When strawberries Season in 2 are California The Maybe biology show 3of life Botrytis cycle Cultural management 4 grown grown Fight The Chemical management Fungicide resistance Resistance management Recent research Resistance

4 Strawberry production Three districts grow 95% of strawberry fruit in CA Northern District Central District Southern District

5 Production (millions of trays) California production regions Northern district Central district Southern district Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month

6 Adapted from: Agrios 2005 Life cycle of Botrytis

7 Cultural management Show where strawberries are grown Season in California Maybe show life cycle

8 Chemical management Most effective method when weather is favorable for the pathogen Multiple applications are made per season Three types: Site-specific, multi-site, biological Photo: G. Holmes

9 Fungicide resistance sensitive individual resistant individual fungicide application regeneration Adapted from: Deisling, H. B. et al

10 Resistance management Rotate modes of action Tank-mix Use fungicides less

11 Previous research Eastern U.S. High levels of resistance to important fungicides for Botrytis gray mold control in strawberries Resistance changing over time Isolates resistant to multiple modes of action California Resistance reported to frequently used fungicides Resistance increasing in a population within a season

12 FUNGICIDE RESISTANCE SCREENING

13 47 fields 888 isolates collected 2 sampling times U.S. Department of Agriculture, National Agricultural Statistics Service

14 Production (millions of trays) Northern district Central district Southern district Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Early-season sampling Late-season sampling

15 Table. Fungicides labeled for Botrytis gray mold of strawberry in California Example trade name Active ingredient(s) FRAC code(s) Topsin Thiophanate-methyl 1 Rovral Iprodione 2 Fontelis Penthiopyrad 7 Kenja 400 Isofetamid 7 Luna Sensation Fluopyram Trifloxystrobin 7 11 Luna Tranquility Fluopyram Pyrimethanil 7 9 Pristine Boscalid Pyraclostrobin 7 11 Merivon Fluxapyroxad Pyraclostrobin 7 11 Scala Pyrimethanil 9 Switch Cyprodinil Fludioxonil 9 12 Elevate Fenhexamid 17 Ph-D Polyoxin-D 19 active ingredient was not tested in this study

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17 No fungicide Cyprodinil Iprodione Fludioxonil Fernández-Ortuño, D. et al Fenhexamid T-methyl Boscalid Fluopyram Penthiopyrad Isofetamid Experimental 1 Experimental 2

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19 Boscalid Fludioxonil Fenhexamid Control

20 Frequency of resistance (%) California conventional Early-season (n=340) Late-season (n= 362) 0 T-methyl Iprodione Boscalid Penthiopyrad Isofetamid Fluopyram Cyprodinil Pyraclostrobin* Fludioxonil Fenhexamid Active ingredient FRAC code

21 Frequency of resistance (%) 100 California organic Early-season (n=92) Late-season (n=94) T-methyl Iprodione Boscalid Penthiopyrad Isofetamid Fluopyram Cyprodinil Pyraclostrobin* Fludioxonil Fenhexamid Active ingredient FRAC code

22 Average CCR 7 6 Early-season Late-season 5 4 b a 3 2 bc c 1 0 Conventional Organic Production type

23 Frequency of phenotype (%) Chemical class resistances Early-season Late-season

24 Genetics behind resistance Chemical Class Gene Genotype observed Hydroxyanilides ERG27 F196C, F412I, F412S Dicarboximides Bos1 I356N, I365N, I365S MBCs Beta-tubulin E198A QoIs Cytochrome b G143A SDHIs SDHb H272R, H272Y, N230I, P225F Genotypes matched phenotypes 94%

25 FUNGICIDE USE SURVEY

26 Active ingredient Peroxyacetic acid Hydrogen dioxode Aureobasidium pullulans Thiophanate-methyl Bacillus amyloliquefaciens Streptomyces lydicus Thiram Extract of Reynoutria Sachalinensis Bacillus subtilis Trifloxystrobin BLAD Fluopyram Extract of Neem Oil Polyoxin D Fluxapyroxad Sodium Tetraborohydrate Decahydrate Penthiopyrad Pyrimethanil Fenhexamid Boscalid Fludioxonil Cyprodinil Pyraclostrobin Captan 15 applications per season 12 day interval Avg. no. applications per season

27 SPECIES IDENTIFICATION

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29 FIELD TRIAL

30 Fungicides applied weekly No fungicides applied Week Sampling time (collection) Resistance testing 1) non-amended control 2) Endura (boscalid) 3) Scholar (fludioxonil) 4) Elevate (fenhexamid)

31 Frequency of resistance (%) Fenhexamid Timing of isolate collection I II III IV V Non-treated Fenhexamid Rotation Tank-mix + rotation Field treatment

32 Frequency of resistance (%) Fludioxonil Timing of isolate collection I II III IV V Non-treated Cyprodinil + fludioxonil Rotation Tank-mix + rotation Fungicide treatment

33 Frequency of resistance (%) Boscalid Timing of isolate collection I II III IV V Non-treated Boscalid + pyraclostrobin Rotation Tank-mix + rotation Fungicide treatment

34 Summary 79 isolates were B. cinerea and one isolate was B. mali. Fungicide resistance frequency was high to FRAC 1, 11, 17 Low frequency of resistance to FRAC 12 Moderate frequency of resistance to FRAC 2, 7, 9 Multi-fungicide resistant isolates were present in all three growing districts. CCR3 was the most common. Few isolates were CCR0 or CCR7. There was an average of 15 applications per season. Captan, a multisite fungicide, was applied the most frequently Site-specific fungicides were applied less than twice per season A within-season increase in CCR frequency was observed in conventional fields.

35 Conclusions Botrytis cinerea is the primary causal agent of strawberry gray mold in California. Other species may exist at low frequencies. The frequency of resistant isolates in a population is a.i. dependent 73% statewide frequency of resistance to fenhexamid 2% statewide frequency of resistance to fludioxonil Fenhexamid was applied less (1.5 times per season) than fludioxonil (2.2) The survey, the CCR shift, and the field trial all indicate that populations of Botrytis may respond rapidly to a single application of a site-specific fungicide The survey: Site-specific fungicides applied < 3 times per season CCR shift: Within-season increase within conventional fields Field trial: Rapid increase in fenhexamid resistance frequency following either one (rotation treatment) or three (fenhexamid treatment) exposures to fenhexamid The field trial indicated that after rapid selection for resistance, the population may revert back to being sensitive if the selection pressure is removed (e.g., fenhexamid).

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