ENHANCEMENT OF BIOCONTROL OF BLUE MOLD WITH THE NUTRIENT ANALOG 2-DEOXY-D-GLUCOSE ON APPLES AND PEARS

The glucose analog, 2-deoxy-D-glucose (2-DOG) enhanced biocontrol of blue mold (caused by Penicillium expansum), the most important postharvest disease of apples and pears. 2-DOG strongly inhibited P. expansum, and of the two antagonists investigated, Pseudomonas syringae was resistant to 2-DOG at 10 mg/ml whereas Sporobolomyces roseus was susceptible. A mutant of S. roseus resistant to 2-DOG was developed. Addition of 2-DOG at 4 mg/ml allowed more than a 10-fold reduction in the concentration of the antagonists applied to fruits without diminishing control. This effect was still apparent at an inoculum of 5 x 10(4) conidia of P. expansum per ml, which greatly exceeds concentrations found under normal commercial conditions. The effect of 2-DOG on biocontrol was stronger on apples than on pears. 2-DOG had no effect on populations of the antagonists, which increased greatly in wounds on apples and pears. The reduction in the concentration of the antagonists needed for control may improve the reliability and economy of the biocontrol system and may have a significant impact on commercialization of this new technology.