Improved methods for monitoring Botrytis cinerea sensitivity to fludioxonil and its prevalent sensitivity status in Gifu Prefecture, Japan

Abstract

We obtained 458 Botrytis cinerea isolates from tomato plants in Gifu Prefecture, Japan, and evaluated them for their sensitivity to the fungicide fludioxonil using mycelial plugs and potato dextrose agar containing 0.2 ppm fludioxonil, as previously reported. Of the isolates, 3.9% had clear growth and were estimated to be ‘low-susceptibility’ isolates based on a microplate or in vivo assay. In addition, we attempted to improve the mycelial plug method because unclear growth was observed in some of the susceptible isolates. The use of mycelial homogenate or paper disks soaked in a spore suspension allowed the sensitivity to be evaluated more clearly than with the use of mycelial plugs.