CHA HARA RACTERIZA CTERIZATI TION ON OF OF BO BOTRYTIS TIS - PowerPoint PPT Presentation

CHA HARA RACTERIZA CTERIZATI TION ON OF OF BO BOTRYTIS TIS CINE NEREA EA RE RESIS ISTANCE ANCE TO O FU FUNGI GICIDES CIDES IN IN CAL ALIF IFORNIA ORNIA STRA RAWB WBERRIES ERRIES SCOTT TT COSSEBOOM SSEBOOM

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

When strawberries are 4 Show where strawberries are Where strawberries are 1 2 3 Season in California The biology of Botrytis Maybe show life cycle Cultural management grown grown grown Fight The Chemical management Fungicide resistance Resistance management Recent research 5 6 7 8 Resistance

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

20 California production regions Production (millions of trays) 18 Northern district Central district 16 Southern district 14 12 10 8 6 4 2 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month

Life cycle of Botrytis Adapted from: Agrios 2005

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

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

Fungicide resistance sensitive individual fungicide application resistant individual regeneration Adapted from: Deisling, H. B. et al. 2008.

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

Previous research Eastern U 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 Califo fornia ▪ Resistance reported to frequently used fungicides ▪ Resistance increasing in a population within a season

FU FUNGICIDE GICIDE RE RESIS ISTANCE ANCE SCREENING REENING

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

20 18 Northern district Production (millions of trays) 16 Central district 14 Southern district 12 10 8 6 4 2 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Early-season sampling Late-season sampling

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

1 2 3 5 6 4 Fernández-Ortuño, D. et al. 2014. No fungicide Cyprodinil Iprodione Fludioxonil Fenhexamid T-methyl Boscalid Fluopyram Penthiopyrad Isofetamid Experimental 1 Experimental 2

Boscalid Fludioxonil Fenhexamid Control

California conventional Early-season (n=340) 100 Late-season (n= 362) 90 Frequency of resistance (%) 80 70 60 50 40 30 20 10 0 T-methyl Iprodione Boscalid Penthiopyrad Isofetamid Fluopyram Cyprodinil Pyraclostrobin* Fludioxonil Fenhexamid 2 7 7 7 9 1 11 12 17 7 Active ingredient FRAC code

Early-season (n=92) California organic Late-season (n=94) 100 90 Frequency of resistance (%) 80 70 60 50 40 30 20 10 0 T-methyl Iprodione Boscalid Penthiopyrad Isofetamid Fluopyram Cyprodinil Pyraclostrobin* Fludioxonil Fenhexamid 1 2 7 7 7 7 9 11 12 17 Active ingredient FRAC code

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

Early-season 50 Late-season Frequency of phenotype (%) 45 40 35 30 25 20 15 10 5 0 0 1 2 3 4 5 6 7 Chemical class resistances

Geneti tics s behin ind d resis sistanc tance Genotype observed Chemical Class Gene ERG27 F196C, F412I, F412S Hydroxyanilides Bos1 I356N, I365N, I365S Dicarboximides Beta-tubulin E198A MBCs Cytochrome b G143A QoIs SDHb H272R, H272Y, N230I, P225F SDHIs Genotypes matched phenotypes 94%

FU FUNGICIDE GICIDE USE E SURVEY VEY

Peroxyacetic acid Hydrogen dioxode Aureobasidium pullulans Thiophanate-methyl Bacillus amyloliquefaciens ▪ 15 applications per season Streptomyces lydicus Thiram Extract of Reynoutria Sachalinensis Active ingredient ▪ 12 day interval Bacillus subtilis Trifloxystrobin BLAD Fluopyram Extract of Neem Oil Polyoxin D Fluxapyroxad Sodium Tetraborohydrate Decahydrate Penthiopyrad Pyrimethanil Fenhexamid Boscalid Fludioxonil Cyprodinil Pyraclostrobin Captan 0 1 2 3 4 5 6 7 8 Avg. no. applications per season

SPE PECIES CIES ID IDENT ENTIFICA IFICATI TION ON

FI FIEL ELD D TRI RIAL AL

No fungicides applied Fungicides applied weekly 2 1 3 4 5 8 9 10 11 12 6 7 Week 2 3 5 1 4 Sampling time (collection) Resistance testing 1) non-amended control 2) Endura (boscalid) 3) Scholar (fludioxonil) 4) Elevate (fenhexamid)

100 Fenhexamid Timing of isolate collection I II III IV V 90 80 Frequency of resistance (%) 70 60 50 40 30 20 10 0 Non-treated Fenhexamid Rotation Tank-mix + rotation Field treatment

100 Fludioxonil 90 Timing of isolate collection I II III IV V 80 Frequency of resistance (%) 70 60 50 40 30 20 10 0 Non-treated Cyprodinil + fludioxonil Rotation Tank-mix + rotation Fungicide treatment

100 Boscalid 90 Timing of isolate collection I II III IV V 80 Frequency of resistance (%) 70 60 50 40 30 20 10 0 Non-treated Boscalid + pyraclostrobin Rotation Tank-mix + rotation Fungicide treatment

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.

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).