SUPPRESSION OF COTTONY LEAK OF CUCUMBER WITH BACILLUS-CEREUS STRAIN UW85

Bacillus cereus strain UW85 was previously shown to suppress seedling diseases caused by oomycetous fungi. In this study, we tested UW85 for suppression of cucumber fruit rot caused by Pythium aphanidermatum. To evaluate UW85, we developed an assay for rotting of cucumber fruits by P. aphanidermatum. Wounded fruits were each inoculated with a suspension containing 500 zoospores of the pathogen and incubated at 32 C for 48 hr. Undiluted culture of UW85, containing approximately 4.4 X 10(8) cells per milliliter, applied to fruit by one of three methods prior to inoculation with the pathogen, significantly reduced rotting (P < 0.05) compared with fruit treated with uninoculated medium or water prior to inoculation with P. aphanidermatum. Culture filtrates and suspensions of UW85 containing less than 1.1 X 10(8) cells per milliliter did not suppress fruit rotting. UW85 cells that were washed and resuspended in sterile medium did suppress rotting.