Timing of fungicide application for Botrytis cinerea control in blackcurrant (ribes nigrum)

Abstract

Flower blight in blackcurrants caused by the fungus Botrytis cinerea has received little attention in New Zealand. To determine the efficacy of a fungicide application in relation to the timing of infection, fungicides were applied 5, 3 and 1 day before as well as immediately after, 1, 2 and 5 days after an infection event. Cyprodinil and fludioxonil (Switch®) were chosen because of the translaminar systemic and protective mode of action. Studies were conducted during the 2006 flowering season in the laboratory and in the field on commercial properties in Canterbury and Nelson. Natural Botrytis flower inoculation and infection events were common during the 2006/07 production season. Results suggest that timing of fungicide application is critical for B. cinerea control in blackcurrants. Protection of flowers was achieved with cyprodinil and fludioxonil applications from 3 days before to 3 days after an inoculation and/or infection event. Reduction of flower infections resulted in increased fruit set.