APPLICATION OF THE PLACKETT-BURMAN EXPERIMENTAL-DESIGN TO EVALUATE NUTRITIONAL-REQUIREMENTS FOR THE PRODUCTION OF COLLETOTRICHUM-COCCODES SPORES

Colletotrichum coccodes is being examined as a biological weed control agent for velvetleaf (Abutilon theophrasti). A modified Richard's sol ution containing V-8 juice has been used to produce C. coccodes spores for growth-chamber and field experiments. Although C. coccodes sporul ates well in this medium, V-8 is not available as a bulk commodity and is too expensive for commercial production. Eight substrates were eva luated as replacements for V-8 juice in modified Richard's solution. S oy protein and casamino acids were equal to V-8 juice for sporulation of C, coccodes. The Plackett-Burman experimental design was used to te st the relative importance of various components of a complex medium b ased on soy protein on mycelium biomass production and sporulation of C. coccodes. A new medium composed of sucrose (20 gill, soy protein (5 g/l), KNO3 (5 g/l), KH2PO4 (5 g/l), MgSO4 (2 g/l), CaCl2 (0.5 g/l), a nd CuSO4 (0.05 g/l) was selected as the base medium for further study in the development of a low-cost and effective medium for C. coccodes spore production.