INTEGRATING BIOLOGICAL-CONTROL AND CALCIUM TREATMENT FOR CONTROLLING POSTHARVEST DECAY OF APPLES

Two nonfungicidal postharvest treatments and N fertility were evaluate d for their effectiveness, singly and in combination, in controlling d ecay (''blue mold'') of apple (Malus xdomestica Borkh.) by Penicillium expansum Link. The antifungal treatments were biological control usin g the antagonist Pseudomonas syringae van Hall (isolate ESC-11 used in BioSave-11 and BioSave-110 products), and pressure infiltration of fr uit with 0.27 M CaCl2. Fruit susceptibility to decay was evaluated usi ng fruit after 3 and 6 months of storage over 2 years. Calcium infiltr ation resulted in a 3-fold increase in Ca content of apple mesocarp. B oth antagonist and Ca treatments reduced the severity and incidence of blue mold decay on 'Delicious' apples. Combining these treatments res ulted in greater control than the individual treatments alone. The eff ects were most apparent on fruit stored 6 months at 1 degrees C. High N fertilization increased decay in only 1 of 2 years of the study. Ant agonist recovery data suggest that the antagonist could be applied imm ediately after Ca treatment. Combining a biocontrol agent with Ca infi ltration may allow reduced rates of both products to be used without c ompromising the control of blue mold. This practice will increase the performance margin for biocontrol with the added benefit of increased Ca to alleviate physiological storage maladies.