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Poster: Biology & Disease Mgmt: Biological Control


The potential use of a Cladosporium sp. as a biological control agent for white mold caused by Sclerotinia sclerotiorum
B. ROBINSON (1), R. Cating (2), K. Frost (2) (1) Oregon State University; Hermiston High School, U.S.A.; (2) Oregon State University, U.S.A.

Sclerotinia scelortiorum (Lib.) de Bary is a pathogenic ascomycete known to cause disease in more than 400 plant species, including white mold in potato. In this study, a fungal contaminant found associated with S. sclerotiorum that appeared to inhibit S. scelortiorum growth was isolated, sub-cultured, and identified. Morphological characteristics and sequence data from internal transcribed spacers 1 and 2, 5.8s rDNA, and Actin and Calmodulin genes were consistent with the unknown fungus belonging to the Cladisporium genus. A bioassay was used to examine inhibition of S. sclerotiorum growth by the Cladisporium isolate. A 5mm plug of the Cladisporium isolate was plated on potato dextrose agar and left to grow for 72 hours before a 5mm plug of S. sclerotiorum was plated 50mm from the Cladisporium plug. Isolates of S. sclerotiorum and Cladisporium were plated alone as controls. The plates (n=10 per treatment) were incubated for 4 days at room temperature with a 12:12 photoperiod. Radial growth of S. sclerotiorum mycelia was measured and the experiment was repeated in entirety one time. Averaging over both experiments, the radii of S. sclerotiorum plated with the unknown isolate was reduced by 34.1 mm (Paired t-test: t = 27.4, df = 19, p < 0.001) when compared to the radii of the S. sclerotiorum plated alone. These data indicate that the Cladisporium isolate has potential use as a bio-control agent against S. sclerotiorum and should be further evaluated in vivo.