Actigard Reduces Anthracnose on Field-grown Strawberry

Abstract

Anthracnose fruit rot (AFR) and crown rot can cause severe economic losses on susceptible `Chandler' and `Camarosa' strawberry in Virginia: `Sweet Charlie' and `Bish' are moderately resistant to resistant. Actigard (acibenzolar-S-methyl), an inducer of systemic acquired resistance, has been effective at reducing black spot and speck on tomato, blue mold on tobacco, and fire blight on apple. The objective of this study was to determine if Actigard, when spray-applied to field-grown strawberry, can reduce AFR better than or equal to several registered fungicides. Four varieties (VAR) (Chandler, Camarosa, Sweet Charlie, and Bish) were treated with four fungicides (FUNG) (water control, azoxystrobin, chlorothalonil, and actigard). Experimental design was a split plot with FUNG as the main plot and VAR as the split plot with four replicates. Standard annual hill system practices were used throughout. Plots were inoculated three times throughout the harvest season with a conidia: water solution of 1 × 106 conidia per mL. Plots were treated with FUNG on a 14-day schedule from bloom to end of season. Plots were visually assessed for anthracnose and fruit were harvested 2× weekly and weighed into four categories: marketable, cull, fruit with anthracnose, and fruit with other diseases. Environmental conditions were conducive for anthracnose development: extended periods of rain and high relative humidity. Plots treated with water control had more AFR, other fruit rots, and higher overall disease ratings than those treated with a compound. Plots treated with actigard had the same level of AFR as did those treated with azoxystrobin. `Chandler' and `Camarosa' had considerably more AFR than `Sweet Charlie' and `Bish' had the least amount over all FUNG.