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

Recent research Maybe show life cycle Show where strawberries are grown Season in California

Fight The Resistance

When strawberries are grown The biology of Botrytis Cultural management Chemical management Fungicide resistance Resistance management Where strawberries are grown

1 2 3 4 5 6 7 8

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

Strawberry production

2 4 6 8 10 12 14 16 18 20

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Production (millions of trays) Month

Northern district Central district Southern district

California production regions

Adapted from: Agrios 2005

Life cycle of Botrytis

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

Cultural management

▪ Most effective method when weather is favorable for the pathogen ▪ Multiple applications are made per season ▪ Three types: Site-specific, multi-site, biological

Chemical management

Photo: G. Holmes

Fungicide resistance

Adapted from: Deisling, H. B. et al. 2008.

sensitive individual resistant individual fungicide application regeneration

Resistance management

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

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

Previous research

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

2 4 6 8 10 12 14 16 18 20

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Production (millions of trays)

Early-season sampling Late-season sampling

Northern district Central district Southern district

active ingredient was not tested in this study

• 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

No fungicide Cyprodinil

1 2 3 4 5 6

Iprodione Fenhexamid Fludioxonil T-methyl Boscalid Fluopyram Penthiopyrad Isofetamid Experimental 1 Experimental 2

Fernández-Ortuño, D. et al. 2014.

Boscalid Fenhexamid Fludioxonil Control

10 20 30 40 50 60 70 80 90 100

T-methyl Iprodione Boscalid Penthiopyrad Isofetamid Fluopyram Cyprodinil Pyraclostrobin* Fludioxonil Fenhexamid

Frequency of resistance (%) Active ingredient FRAC code

California conventional

Early-season (n=340) Late-season (n= 362)

1

2 7 7 7 7 9 11 12 17

10 20 30 40 50 60 70 80 90 100

T-methyl Iprodione Boscalid Penthiopyrad Isofetamid Fluopyram Cyprodinil Pyraclostrobin* Fludioxonil Fenhexamid

Frequency of resistance (%) Active ingredient FRAC code

California organic

Early-season (n=92) Late-season (n=94)

1 2 7 7 7 7 9 11 12 17

1 2 3 4 5 6 7 Conventional Organic Average CCR Production type

Early-season Late-season

b a bc c

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

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 Geneti tics s behin ind d resis sistanc tance Genotypes matched phenotypes 94%

FU FUNGICIDE GICIDE USE E SURVEY VEY

1 2 3 4 5 6 7 8

Captan Pyraclostrobin Cyprodinil Fludioxonil Boscalid Fenhexamid Pyrimethanil Penthiopyrad Sodium Tetraborohydrate Decahydrate Fluxapyroxad Polyoxin D Extract of Neem Oil Fluopyram BLAD Trifloxystrobin Bacillus subtilis Extract of Reynoutria Sachalinensis Thiram Streptomyces lydicus Bacillus amyloliquefaciens Thiophanate-methyl Aureobasidium pullulans Hydrogen dioxode Peroxyacetic acid

• Avg. no. applications per season

Active ingredient

▪ 15 applications per season ▪ 12 day interval

SPE PECIES CIES ID IDENT ENTIFICA IFICATI TION ON

FI FIEL ELD D TRI RIAL AL

Resistance testing 1) non-amended control 2) Endura (boscalid) 3) Scholar (fludioxonil) 4) Elevate (fenhexamid)

Week

1 2 3 4 5 6 7 8 9 10 11 12

Sampling time (collection)

1 2 3 4 5

Fungicides applied weekly No fungicides applied

10 20 30 40 50 60 70 80 90 100 Non-treated Fenhexamid Rotation Tank-mix + rotation

Frequency of resistance (%) Field treatment

Fenhexamid

I II III IV V

Timing of isolate collection

10 20 30 40 50 60 70 80 90 100 Non-treated Cyprodinil + fludioxonil Rotation Tank-mix + rotation

Frequency of resistance (%)

Fungicide treatment

Fludioxonil

I II III IV V Timing of isolate collection

10 20 30 40 50 60 70 80 90 100 Non-treated Boscalid + pyraclostrobin Rotation Tank-mix + rotation

Frequency of resistance (%) Fungicide treatment

Boscalid

I II III IV V Timing of isolate collection

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).