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 b lue mold (caused by Penicillium expansum), the most important postharv est disease of apples and pears. 2-DOG strongly inhibited P. expansum, and of the two antagonists investigated, Pseudomonas syringae was res istant to 2-DOG at 10 mg/ml whereas Sporobolomyces roseus was suscepti ble. 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 conce ntration of the antagonists applied to fruits without diminishing cont rol. This effect was still apparent at an inoculum of 5 x 10(4) conidi a of P. expansum per ml, which greatly exceeds concentrations found un der normal commercial conditions. The effect of 2-DOG on biocontrol wa s stronger on apples than on pears. 2-DOG had no effect on populations of the antagonists, which increased greatly in wounds on apples and p ears. The reduction in the concentration of the antagonists needed for control may improve the reliability and economy of the biocontrol sys tem and may have a significant impact on commercialization of this new technology.