STRAWBERRY GRAY MOLD: sustainable management and ...
Fungicide usage survey 32 strawberry fields were surveyed for fungicide usage in 2016. A summary of usage for products labeled for gray mold of strawberry is below: • Average number of applications per season: 15 • Average application interval: 12 days • Number of different modes of action applied: 13 Trilogy
Ph-D Fontelis
Product
Merivon Scala Prev-Am Ultra Elevate Pristine Switch Captan 0
2 4 6 8 Avg. no. applications/season Figure 2. Average number of applications/season of the top ten most applied fungicides labeled for gray mold of strawberry in 32 California strawberry farms in 2016.
Table 1. Fungicides labeled for gray mold of strawberry in California Example trade name Active ingredient(s) FRAC* Topsin Thiophanate-methyl 1 Rovral Iprodione 2 Fontelis Penthiopyrad 7 Kenja 400 Isofetamid 7 Luna Tranquility Fluopyram + pyrimethanil 7 9 Luna Sensation Fluopyram + trifloxystrobin 7 11 Merivon Fluxapyroxad + pyraclostrobin 7 11 Pristine Boscalid + pyraclostrobin 7 11 Scala Pyrimethanil 9 Switch Cyprodinil + fludioxonil 9 12 Elevate Fenhexamid 17 CaptEvate Fenhexamid + captan 17 M4 Ph-D Polyoxin-D 19 Thiram Thiram M3 Captan Captan M4 Prev-Am Ultra Sodium tetraborate decahydrate NL*** Trilogy Neem Oil 46 Fracture Banda de Lupinus albus doce BM 01 Actinovate AG/SP Streptomyces lydicus NL Double Nickel LC/55 Bacillus amyloliquefaciens 44 Coragen Chlorantraniliprole NL Serenade ASO Bacillus subtilis 44 Regalia Extract of Reynoutria sachalinensis 46 Oxidate 2.0 H2O2 + Peroxyacetic acid NL Botector Aureobasidium pullulans NL O Single-site mode of action**; conventional use only O Multi-site mode of action; conventional use only O OMRI approved
STRAWBERRY GRAY MOLD: sustainable management and fungicide resistance
*Fungicide Resistance Action Committee; active ingredients are grouped according to cross resistance behavior. **Resistance is a risk with single-site fungicides. Risk varies by the mode of action (Figure 1). ***NL = Not listed in 2017 FRAC code list.
strawberry.calpoly.edu Figure 3. Left: Early symptoms of gray mold usually start as brown water-soaked lesions near the calyx. Right: Late signs of gray mold appear as a velvety gray mold.
Photo credit: G. Holmes (inside) and S. Cosseboom (outside)
Strawberry gray mold is a fruit rot that is primarily caused by the fungal plant pathogen Botrytis cinerea. This disease is favored by wet weather and can cause high losses in yield and postharvest decay. Gray mold can be managed by both chemical and cultural methods. Cultural methods: • Harvest fruit at optimum maturity • Remove rotten fruit and senescent foliage from field • Increase space between plants to make promote air movement • Use plastic mulches to force water off beds to keep fruit dry Chemical methods: • Use effective products; consult UC IPM • Make applications preventively • Time applications to coincide with favorable weather conditions
Early-season
Fungicide resistance in Botrytis cinerea Recent reports have shown that Botrytis cinerea is becoming resistant to fungicides that were once very effective. If the Botrytis cinerea population in your field is resistant to the fungicide you use, the efficacy of that fungicide is compromised. In 2016, a survey of 37 conventional strawberry fields distributed throughout the Oxnard, Santa Maria, Salinas and Watsonville growing areas tested 702 isolates for resistance to ten fungicides. This survey found varying levels of resistance to all ten active ingredients tested (Figure 1). Resistance also tended to increase from the beginning to the end of the season. This may be due to the average of 15 individual fungicide applications per season (Figure 2).
Resistance management guidelines • • •
• •
Spray less often and when weather favors disease Rotate between modes of action (Table 1) Each time a single-site mode of action fungicide is applied, tank-mix it with a multi-site mode of action fungicide (e.g., captan or thiram) Use labeled rates with a recently calibrated sprayer Apply multi-site or organically approved fungicides alone when disease pressure is low
Late-season
Thiophanate-methyl (1)
Active ingredient (FRAC code)
What is strawberry gray mold?
Iprodione (2) Isofetamid (7) Penthiopyrad (7) Fluopyram (7) Boscalid (7) Cyprodinil (9) Pyraclostrobin* (11)
Fludioxonil (12) Fenhexamid (17) 0
20
40
60
80 100
Frequency of resistance (%)
Figure 1. Early-season and late-season frequencies of resistance to ten active ingredients from 702 isolates collected in the Northern, Central, and Southern strawberry growing districts of California in 2016. *fewer isolates (415) were tested for resistance to pyraclostrobin due to widespread nature of strobilurin resistance.
Ph-D Fontelis
Product
Merivon Scala Prev-Am Ultra Elevate Pristine Switch Captan 0
2 4 6 8 Avg. no. applications/season Figure 2. Average number of applications/season of the top ten most applied fungicides labeled for gray mold of strawberry in 32 California strawberry farms in 2016.
Table 1. Fungicides labeled for gray mold of strawberry in California Example trade name Active ingredient(s) FRAC* Topsin Thiophanate-methyl 1 Rovral Iprodione 2 Fontelis Penthiopyrad 7 Kenja 400 Isofetamid 7 Luna Tranquility Fluopyram + pyrimethanil 7 9 Luna Sensation Fluopyram + trifloxystrobin 7 11 Merivon Fluxapyroxad + pyraclostrobin 7 11 Pristine Boscalid + pyraclostrobin 7 11 Scala Pyrimethanil 9 Switch Cyprodinil + fludioxonil 9 12 Elevate Fenhexamid 17 CaptEvate Fenhexamid + captan 17 M4 Ph-D Polyoxin-D 19 Thiram Thiram M3 Captan Captan M4 Prev-Am Ultra Sodium tetraborate decahydrate NL*** Trilogy Neem Oil 46 Fracture Banda de Lupinus albus doce BM 01 Actinovate AG/SP Streptomyces lydicus NL Double Nickel LC/55 Bacillus amyloliquefaciens 44 Coragen Chlorantraniliprole NL Serenade ASO Bacillus subtilis 44 Regalia Extract of Reynoutria sachalinensis 46 Oxidate 2.0 H2O2 + Peroxyacetic acid NL Botector Aureobasidium pullulans NL O Single-site mode of action**; conventional use only O Multi-site mode of action; conventional use only O OMRI approved
STRAWBERRY GRAY MOLD: sustainable management and fungicide resistance
*Fungicide Resistance Action Committee; active ingredients are grouped according to cross resistance behavior. **Resistance is a risk with single-site fungicides. Risk varies by the mode of action (Figure 1). ***NL = Not listed in 2017 FRAC code list.
strawberry.calpoly.edu Figure 3. Left: Early symptoms of gray mold usually start as brown water-soaked lesions near the calyx. Right: Late signs of gray mold appear as a velvety gray mold.
Photo credit: G. Holmes (inside) and S. Cosseboom (outside)
Strawberry gray mold is a fruit rot that is primarily caused by the fungal plant pathogen Botrytis cinerea. This disease is favored by wet weather and can cause high losses in yield and postharvest decay. Gray mold can be managed by both chemical and cultural methods. Cultural methods: • Harvest fruit at optimum maturity • Remove rotten fruit and senescent foliage from field • Increase space between plants to make promote air movement • Use plastic mulches to force water off beds to keep fruit dry Chemical methods: • Use effective products; consult UC IPM • Make applications preventively • Time applications to coincide with favorable weather conditions
Early-season
Fungicide resistance in Botrytis cinerea Recent reports have shown that Botrytis cinerea is becoming resistant to fungicides that were once very effective. If the Botrytis cinerea population in your field is resistant to the fungicide you use, the efficacy of that fungicide is compromised. In 2016, a survey of 37 conventional strawberry fields distributed throughout the Oxnard, Santa Maria, Salinas and Watsonville growing areas tested 702 isolates for resistance to ten fungicides. This survey found varying levels of resistance to all ten active ingredients tested (Figure 1). Resistance also tended to increase from the beginning to the end of the season. This may be due to the average of 15 individual fungicide applications per season (Figure 2).
Resistance management guidelines • • •
• •
Spray less often and when weather favors disease Rotate between modes of action (Table 1) Each time a single-site mode of action fungicide is applied, tank-mix it with a multi-site mode of action fungicide (e.g., captan or thiram) Use labeled rates with a recently calibrated sprayer Apply multi-site or organically approved fungicides alone when disease pressure is low
Late-season
Thiophanate-methyl (1)
Active ingredient (FRAC code)
What is strawberry gray mold?
Iprodione (2) Isofetamid (7) Penthiopyrad (7) Fluopyram (7) Boscalid (7) Cyprodinil (9) Pyraclostrobin* (11)
Fludioxonil (12) Fenhexamid (17) 0
20
40
60
80 100
Frequency of resistance (%)
Figure 1. Early-season and late-season frequencies of resistance to ten active ingredients from 702 isolates collected in the Northern, Central, and Southern strawberry growing districts of California in 2016. *fewer isolates (415) were tested for resistance to pyraclostrobin due to widespread nature of strobilurin resistance.
