The influence of filamentous fungi isolated from petals of bean and rapeseed on white mold caused by Sclerotinia sclerotiorum was evaluated. In laboratory trials, macerates of agar plugs containing hyphal fragments of the pathogen in combination with individual fungi were applied onto celery petioles, and subsequent lesion diameters were recorded. The efficacy of 10 fungi exhibiting a spectrum of lesion suppression on celery was correlated with the efficacy of the same fungi in growth-room (r = 0.78, P = 0.005) and greenhouse (r = 0.68, P = 0.032) trials. From 315 isolates of fungi evaluated in the laboratory trials, the 10 most suppressive isolates were selected and evaluated in growth-room trials. Spores of the test fungi were applied onto flowers simultaneously with, and up to 24 h after, inoculation with ascospores of S. sclerotiorum. The most suppressive fungi included isolates of Alternaria alternata, Drechslera sp., Epicoccum purpurascens, Fusarium graminearum, Fusarium heterosporum, and Myrothecium verrucaria. These fungi did not provide consistent control of white mold of bean in a field test repeated four times in 1988. However, Drechslera sp. and E. purpurascens significantly reduced the incidence of white mold in one and two trials, respectively. Combination treatments of A. alternata and Benlate (1.1 kg active ingredient ha−1) suppressed white mold significantly more than either treatment alone in one of four trials. Key words: Sclerotinia sclerotiorum, biological control, fungicide interaction.
EFFECT OF CONIOTHYRIUM MINITANS AND TRICHODERMA HARZIANUM IN THE BIOLOGICAL CONTROL OF WHITE MOLD DISEASE (SCLEROTINIA SCLEROTIORUM) IN LETTUCE (LACTUCA SATIVA L.)
