POSTHARVEST BIOLOGICAL-CONTROL OF PENICILLIUM-DIGITATUM DECAY ON CITRUS-FRUIT BY BACILLUS-PUMILUS

A new antagonist/pathogen combination is reported, with Bacillus pumilus showing strong antagonistic activity against Penicillium digitatum. B. pumilus (1.6 x 10(10) to 1.6 x 10(12) cfu ml-1) gave significant control of P. digitatum infection in Valencia orange, which was as effective as imazalil (500-mu-g ml-1) and was significantly better than benomyl treatment (500-mu-g ml-1). When lower concentrations of B. pumilus (1.9 x 10(7) to 1.9 x 10(9) cfu ml-1) were tested on Washington Navel orange and Lisbon lemon fruit, the antagonist caused significant control of P. digitatum infection at two inoculum levels (6.5 x 10(4) and 6.5 x 10(5) spores ml-1). Concentrations of both the pathogen and the antagonist affected the biocontrol effect.