PRE AND POST-INFECTION ACTIVITY OF PYRACLOSTROBIN FOR CONTROL OF ANTHRACNOSE FRUIT ROT OF STRAWBERRY CAUSED BY COLLETOTRICHUM ACUTATUM

Authors: Turechek, William; PERES, NATALIA - U. FLORIDA

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 5/12/2005
Publication Date: 5/12/2005
Citation: Turechek, W., Peres, N. 2005. Pre and post-infection activity of pyraclostrobin for control of anthracnose fruit rot of strawberry caused by colletotrichum acutatum. BARC Poster Day.

Interpretive Summary:

Technical Abstract: Strawberry anthracnose is one of the most serious diseases in commercial strawberry fields. The disease is managed primarily through application of fungicides applied either on a calendar schedule or in response to disease forecasts. However, unpredicted, sporadic rain events lead to infection events that occur in the absence of fungicide protection. Under this scenario, grower’s options are limited to application of fungicides with post-infection activity, but little information is available to guide growers how to best apply fungicides to obtain optimal disease control under these conditions. In this study, the efficacy of pre- and post-infection applications of pyraclostrobin (Cabrio EC) was evaluated under field conditions over two seasons in Florida and New York. The varieties ‘Camarosa’ and ‘Festival’ grown in an annual production system were used in Florida; the varieties ‘Kent’ and ‘Jewel’ grown in a matted row system were used in New York. Symptomatic fruit (FL) or an inoculum suspension of C. acutautm (NY) were used to inoculate field plots under short (8 h) or long (24 h) wetting regimes. Cabrio applications were made 16 or 24 h prior to inoculation and 4, 8, or 24 h following inoculation and their wetting event. Anthracnose incidence in the untreated controls always exceeded the incidence in the treated plots and was higher on treatments subjected to the long wetting regime. For ‘Camarosa’ and ‘Jewel’, both moderately susceptible cultivars, post-infection treatments performed as well or slightly better than the protective treatments. Disease incidence was similar with post-infection treatments with long or short wetting. For ‘Festival’, a less susceptible cultivar, pre-and post-infection treatments performed similarly for the short wetting period. However, the protective treatment was better under the long wetting period. For ‘Kent’, a highly susceptible cultivar, the protective treatment provided greater disease control than any of the post-infection applications under both wetting regimes. However, conditions for infection during the ‘Kent’ trial were exceptionally favorable with daytime temperature exceeding 32 C during their wetting periods. Results suggest that for short wetting events, such as those followed by a late afternoon thunderstorms, or on less susceptible cultivars, Cabrio may be applied after an infection event. For longer wetting events or on more highly susceptible cultivars, fungicides may have to be applied preventively.