Effects of Municipal Sludge Compost Curing Time on Suppression of Pythium and Rhizoctonia Diseases of Ornamental Plants

Abstract

Composts prepared from municipal sewage sludge and formulated into container media initially were conductive to both Pythium and Rhizoctonia damping-off. Sludge composts cured 4 mo, when temperatures in the center of piles were <60 C, consistently suppressed Pythium damping-off but not Rhizoctonia damping-off. Additional storage of media prepared with 4-mo-cured sludge compost for a 4-wk period consistently rendered them suppressive to both diseases. The levels of suppressiveness induced in such media amended with 25% (v/v) sludge compost were adequate to avoid plant losses caused by Rhizoctonia solani or Pythium spp. in greenhouse and nursery crops over 5-mo and 2-yr production cycles, respectively.