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Is the super-resistant fungus among us? Genesis and consequences of recent epidemic of Botrytis cinerea in strawberry fields in Florida.
A. AMIRI (1), S. M. Heath (1), N. N. Peres (1). (1) University of Florida, Wimauma, FL, U.S.A.

Strawberry growers in Central Florida experienced a severe epidemic of <i>Botrytis cinerea</i>, the causal agent of Botrytis fruit rot (BFR), in the last 10 days of February 2012. Economic consequences are being estimated but immediate investigations should be undertaken to understand the reasons behind such a sudden epidemic. Herein, we address the role of two major possible factors, the effect of weather conditions on the disease development and the prevalence of resistance to multiple fungicides. The disease cycle of <i>B. cinerea</i> can be completed in 15 to 20 days if favorable conditions persist for only a few hours (14) in the field. The Strawberry Advisory System (SAS) for monitoring the risk for <i>B. cinerea</i> and <i>Colletotrichum acutatum</i> indicated that between Feb 6 and 7 and Feb 17 and 18, leaf wetness duration and temperatures were highly conducive for BFR. These dates corresponded to peak bloom of early cultivars and beginning of bloom of mid-season and late cultivars, respectively. Severe symptoms of BFR were observed within the following 15 days. Furthermore, based on a recent fungicide resistance monitoring throughout Florida, a large number of <i>B. cinerea</i> isolates investigated were resistant to at least four of the most common fungicides used for BFR control. The widespread of <i>B. cinerea</i> populations with multiple fungicide-resistance has worsened the situation especially where appropriate sprays have not been applied at bloom. The implementation of programs warranting continuous monitoring of risks linked to disease and fungicide resistance development will be key components of future BFR management in strawberries.<p><p>Keywords: Fungus, Fruits-Nuts, Strawberry

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