Postharvest biological control of gray mold rot of strawberry with Cryptococcus laurentii

Cryptococcus laurentii was evaluated for its activity in reducing postharvest gray mold decay of strawberries caused by Botrytis cinerea. In the test on PDA (potato-dextrose agar medium) plates, agar disks of C. laurentii NYDA (nutrient yeast dextrose agar) cultures placed on PDA plates seeded with pathogens did not inhibit the growth of B. cinerea. Spore germination of pathogens in PDB (potato dextrose broth) was greatly controlled in the present of living cell suspensions of Crytococcus laurentii. Washed cell suspensions of yeast controlled gray mold better than yeast in culture broth. Treatments of wounds with autoclaved cell cultures or cell-free cultures filtrate did not prevent decay. The concentrations of antagonists had significant effects on biocontrol effectiveness: the higher the concentration of the antagonist, the lower the disease incidence regardless of whether the fruit was stored at 20℃ for 3 days or 2℃ for 20 days. The experiments of reducing natural decay development of intact fruit gave similar result. Thus, C. laurentii could be an alternative to synthetic fungicides for control of postharvest gray mold disease on strawberries.