EFFECTS OF COMPOSTS AND SOIL AMENDMENTS ON SOIL MICROFLORA AND PHYTOPHTHORA ROOT AND CROWN ROT OF BELL PEPPER

Three field tests were established at Boynton Beach, Florida during 19 92-1995, to evaluate various composts and soil amendments incorporated into the top 20 cm of beds for control of Phytophthora root and crown rot of bell pepper caused by Phytophthora capsici. Test plots were tr eated with one of the following: chitosan, crab shell waste, humate, m unicipal solid waste, perennial peanuts, seed peanuts, sewage sludge-y ard trimming (SY), and wood chips. Untreated plots served as controls. Soil populations of five microbial functional groups and total microb ial activity were monitored by measuring fluorescein diacetate hydroly sis analysis. Two plantings (II September and 16 November 1995) of cv. Boynton Belie were evaluated in each test. Chitosan (0.2%, w/v) reduc ed disease incidence and severity compared with controls in one test. Perennial peanuts reduced disease incidence and severity of Phytophtho ra root and crown rot in another test. Several treatments, especially SY and wood chips, increased total microbial activity and soil populat ions of certain microbial functional groups, some of which were negati vely correlated with disease incidence and severity.