DEVELOPMENT OF COLLETOTRICHUM-GLOEOSPORIOIDES F-SP CLIDEMIAE AND SEPTORIA-PASSIFLORAE INTO 2 MYCOHERBICIDES WITH EXTENDED VIABILITY

Two potential mycoherbicides were formulated for extended viability: o ne, containing Colletotrichum gloeosporioides f. sp. clidemiae as the active ingredient, was effective against Koster's curse (Clidemia hirt a); and the other, containing Septoria passiflorae, was effective agai nst banana poka (Passiflora tripartita var. tripartita). Microcycle co nidiation of both fungi occurred on the surface of solid media inocula ted with spore suspensions greater than or equal to 1 x 10(6) conidia per ml, ca. 1.67 x 10(4) conidia per cm(2). In 4 days, C. g. f. sp. cl idemiae produced 5 x 10(6) conidia per cm(2) after incubation at 25 de grees C under continuous illumination on the surface of potato-dextros e agar adjusted to 3% agar. In 3 weeks, S. passiflorae produced 8.6 x 10(7) conidia per cm(2) after incubation on 10% Gerber Mixed Cereal fo r Baby agar, while on agitated potato-dextrose broth the production wa s 3.9 x 10(7) conidia per mi at 21 degrees C under continuous illumina tion after 4 days incubation. Spores of C. g. f. sp. clidemiae and S. passiflorae, harvested by scraping the surfaces of solid cultures, wer e mixed in kaolin, dried, and stored at -18 and 1 degrees C. They main tained greater than 84% viability for over 4 months and greater than 9 5% viability for 6 months, respectively. Spores of S. passiflorae harv ested from liquid culture and stored at less than or equal to 1 degree s C, mixed in kaolin and/or by lyophilization, maintained 97% viabilit y for greater than or equal to 1 year. C. g. f. sp. clidemiae spores p roduced in liquid culture had low viability and were killed by lyophil ization. Viability was optimally maintained in both fungi when they we re stored at -18 degrees C. Viability of spores of both fungi stored a s a kaolin formulation at 22 degrees C was short-lived. No significant differences in pathogenicity were found in spores as a kaolin formula tion after 4 months of storage. The shelf life of stored C. g. f. sp. clidemiae-kaolin was not affected by rehydrating in a 30% sucrose solu tion; whereas significant loss of viability occurred when the spore-ka olin mixtures were rehydrated in sterile distilled water (SDW). Rehydr ation of the mycoherbicide containing S. passiflorae in SDW did not de crease its activity. Both fungi produced a significantly higher number of lesions when applied to host plants suspended in 2% sucrose-0.5% g elatin solution than in SDW. Also, the number of lesions produced incr eased linearly with increases in inoculum. There was no significant di fference in pathogenicity between freshly harvested spores and kaolin- spore mixtures stored for 4 months.