Efficacy of commercial formulation of two biofungicides for control of blue mold and gray mold of apples in cold storage

The effectiveness of a new biofungicide, Bio-Save 11, based on a strain of Pseudomonas syringae (ESC-11 = L-59-66) and formulated as a 10% wettable powder was evaluated and compared to thiabendazole and fresh cells of the bacterium using two apple (Malus X domestica Borkh.) cultivars in each of two seasons. The effectiveness of a 10% wettable powder of another strain of Pseudomonas syringae, ESC-10, was also evaluated. The dry wettable powder formulation of strain ESC-11 (ESC-11 WP) of P. syringae performed as well as the fresh cells of the bacterium. Application of a suspension containing diphenylamine, conidia of Penicillium expansum Link and Botrytis cinerea Pers.:Fr. (both at 1 x 10(4) conidia/ml) and ESC-11 WP at the proposed label rate to wounded Golden Delicious and Delicious apples controlled fruit decay as effectively as the fresh cells of the bacterium applied in a similar suspension. The control achieved with both suspensions of this antagonist was comparable to that with thiabendazole. ESC-10 WP significantly reduced the incidence of disease; but often less effectively than with the formulated preparation (ESC-11 WP) or the fresh cells of P. syringae (L-59-66). Populations of the biocontrol agent from either formulated or fresh preparations increased in the wounds more than 10-fold during 3 months in storage at 1 degrees C and appeared to reach wound carrying capacity at approximately 1x10(8) CFU/wound. The dry commercial formulation did not adversely affect the performance of the bacterium for control of blue mold and gray mold of apples in the presence of diphenylamine applied at the label recommended rate after harvest. Published by Elsevier Science Ltd.