REACTION OF SEED-BORNE SOYBEAN FUNGAL PATHOGENS TO CERCOSPORIN

Cercosporin is a nonspecific toxin produced by Cercospora kikuchii and C. sojina, seedborne soyabean (Glycine max) fungal pathogens. Cercosporin was extracted from the mycelium of C. sojina, purified, and assayed for inhibition of mycelial radial growth of selected seedborne soyabean fungal pathogens in vitro. Cercosporin was fungistatic to the following under 24 hours light: Alternaria alternata, Diaporthe phaseolorum f. sp. sojae, Fusarium sp., Macrophomina phaseolina, and Phomopsis longicolla. Radial growth of C. kikuchii, C. sojina, and Colletotrichum truncatum was not inhibited when incubated under 24 hours light or dark. This inhibition suggested involvement of cercosporin in seed colonisation by Cercospora spp.