Improving fungicidal control of Botrytis bunch rot

Abstract

Laboratory and field studies were undertaken to determine if potassium metabisulphite (KMS) controls Botrytis bunch infection when applied near harvest.
The laboratory studies showed that 3 g/L KMS inhibited the germination of Botrytis spores and that the effect was greater when the spores were incubated in grape juice. Volatiles emanating from suspensions of KMS inhibited germ tube elongation but not spore germination. Experiments using single inoculated berries showed that KMS inhibits the development of Botrytis when applied up to 48 hours after inoculation. However both laboratory and field studies showed that KMS had little effect on sporulation from berries infected more than 48 hours previously. Applications of 4 g/L KMS on one or two occasions at various times between veraison and harvest did not inhibit sporulation from infected berries. Further work needs to done to evaluate KMS and other fungicides for use just before harvest.

Summary

Effect of potassium metabisulphate on Botrytis – kills spores and inhibits germtube growth if it is applied within 48 hours from infection; sporulation from infected berries is also inhibited. After 48 hours no effect.