Agent In-Service Training - Effective gray mold management Guido Schnabel Clemson University

Monitoring results from 8 states, 2012 Summary Monitoring results from 8 states, 2012 % Switch (fludioxonil) Rovral Switch Elevate Switch (cyprodinil) Pristine (boscalid) Pristine (pyraclo) Topsin M No resistance Moderate-high risk of resistance

Control (Untreated) Sensitive Resistant Fludioxonil Switch Rovral Topsin M Cabrio Control (Untreated) Endura Cyprodinil Elevate Sensitive Resistant

Location-specific recommendation Cyprodinil

Outlook for 2013 Resistance to multiple fungicides is here to stay (fitness, continued selection) Resistance profile varies from farm to farm Gray mold has not been a huge issue due to dry springs, but what if the weather changes? Anti-resistance management strategies need to be implemented

2013 monitoring SC location 1 Elevate Rovral Pristine Topsin M Luna Merivon Fontelis Switch Scala Switch Control

2013 monitoring SC location 2 GA location 1 Pristine Topsin M Pristine Merivon Fontelis Switch Scala Switch Elevate Rovral Luna SC location 2 GA location 1

2013 monitoring NC location 1 Elevate Rovral Pristine Topsin M Switch Merivon Fontelis Scala Switch Luna NC location 1

Strategies to combat resistance Cultural methods to keep fungus from infection Plasticulture starts with little inoculum Avoid leaf wetness (drip, not overhead; aeration in tunnels; plastic cover during rain?) Frugal fertilizer use (to avoid excessive growth) Sanitation (remove dead plant material and rotten fruit especially in early pickings) Increase spacing between plants?

Strategies to combat resistance Moderate use of site-specific fungicides Spray them only when needed and avoid spraying ineffective materials apply Thiram/captan prior to bloom, ROTATE others during bloom sprays (4 sprays max) spray prior to rain events not calendar-based get a resistance profile asap (Clemson service)

Best Fungicides Use broad spectrum fungicides as your primary weapons Thiram Granuflo (4.4 lbs/acre or 2.2 lbs/100 gal; 5 applications max; 1 d REI; 3 d PHI) Captan 80 WDG (2 to 4 lbs/acre; 30 lbs/year max; 24 h REI; 0 d PHI) Fontelis, Endura (SDHIs) Scala (AP) Elevate, Captevate (HA) Rovral (DC) Switch (PP +AP)

Other Fungicides Topsin M (no effect on gray mold and most Anthracnose) Pristine, Merivon (2014), Luna Sensation (2014) SDHI + QoI (good for gray mold BUT why spray and select for resistance to mildew or Anthracnose if not necessary?) Adament, Quadris Top, Quilt Xcel QoI + DMI (not effective for gray mold, bad choice for Anthracnose (why not spray QoI straight?) Inspire Super AP + DMI (good for gray mold BUT why spray for mildew if not necessary?)

Collecting and mailing gray mold samples for fungicide resistance profiling Flowers Send 20 to 40 dead strawberry flowers OR Any symptomatic plant tissue After incubation 22ºC-2 days

-Obtain cotton swabs individually wrapped Fruit -Obtain cotton swabs individually wrapped -Collect 10 individual berries with FRESH gray mold lesions -PLEASE: Do not collect from old mummies or discarded fruit on the ground -Use a fresh cotton swab for each berry and carefully rub one side of the swab on the diseased portion of each berry without touching the fruit itself -Return the swab to its individual package or place bulk swabs into plastic bag Yes NO Yes NO

E-mail: schnabe@clemson.edu Mail the samples to: Guido Schnabel Clemson University 113 Long Hall Clemson, SC 29634 E-mail: schnabe@clemson.edu Note: do not forget to indicate LEGIBLY the origin of the sample, your name, and e-mail so that we can send you the report electronically.