Preharvest applications of fungicides and a biocontrol agent for postharvest management of gray mold of strawberry fruit

Gray mold (Botrytis cinerea) is a ubiquitous disease of strawberry fruit. With the loss of older protective fungicides, new alternatives are needed. In field trials, 2 or 3 preharvest sprays reduced postharvest gray mold from 86% in the check to 9, 24, and 27% by the fungicides fludioxonil/cyprodinil, fenhexamid, and boscalid/pyraclostrobin, respectively. In contrast, decay incidence with the biocontrol yeast Candida oleophila (Aspire) was 78%. Populations of the yeast on treated fruit decreased from 10 to 0 cfu/mm super(2) within 0 to 20 h after application. Similar results were obtained on laboratory-treated fruit, indicating that abiotic factors in the field did not cause the decline in population size. Furthermore, incubation of the biocontrol agent in water/fruit-disk solutions did not affect its viability. Thus, the yeast is not competitive in the phyllosphere or population levels are too low to effectively compete against B. cinerea. The new fungicides, each belonging to a new class, offer the best future management strategies.