Survival of dicarboximide-resistant strains of Botrytis cinerea in plant debris during summer in Israel.

Survival- of Botrytis cinerea was monitored during two summer seasons. Mycelium and conidia were found dead on the surface of plant debris within 2 months of incubation, whereas a high level of viability was detected in thallus of the pathogen which was 1-2 mm inside the dry host tissue. Of the 148 samples of infected senescing cucumber female fruits, 8% survived seven warm months; half of these isolates of B. cinerea were resistant to dicarboximides (5 (µ/ml iprodione). Of the stems of cucumber infected with B. cinerea in winter, 18% yielded the pathogen at the beginning of the following winter; 15% of the surviving isolates were resistant to dicarboximides. Cucumber seedlings artificially infected by B. cinerea did not yield the pathogen longer than 9 weeks after establishment of infection, even when incubated in the shade. Plant debris with symptoms of gray mold were kept in the shade during the summer; at the beginning of winter it was possible to establish infection of B. cinerea from the dry debris. [ABSTRACT FROM AUTHOR]