Caption title. "August 1988." At head of title: Project summary. "EPA/600-S2-88-024."

"Efficacy of composted municipal sludge (CMS) for suppression of Phytophthora root rot of soybean in field soil and for suppression of Rhizoctonia and Pythium diseases of ornamental plants produced in container media was investigated over a 3-year period. CMS increased yields of soybean by improving soil fertility and/or by partial control of Phytophthora root rot (PRR). Disease-enhancing effects of salt in the CMS were controlled with a selective fungicide. In the absence of the fungicide, beneficial effects were obtained only by application of CMS at least 3 months prior to planting with cultivars tolerant to PRR. Increased yields of soybeans were observed when high rates of CMS were applied to corn crops and soybeans were grown in the next year without further CMS application. No residual effects were observed from high rates of CMS applied to soybeans. All container media prepared with CMS cured 4 months or more and stored 4 weeks after formulation became consistently suppresslve to Rhizoctonia and Pythium diseases of ornamentals at levels adequate to avoid losses under commercial conditions. An unknown beneficial microflora involved in suppression, if present, survived in the outer low-temperature layer of curing piles only. Several bacterial and fungal isolates were identified that effectively induced suppression to Rhizoctonia and Pythium "damping-off" in CMS media. The relative contributions of these microbes to the overall suppressive effects remain to be determined. Most bacterial strains were more efficacious in combination with an isolate of Trichoderma. A synergistic interaction was found among an isolate of Trichoderma hamatum and of Flavobacterium balustinum for suppression of Rhizoctonia damping-off. These isolates, if added to conducive CMS media, consistently rendered them suppressive in the absence of the 4-week incubation period required for development of natural suppression."