Comparison of Suppressiveness of Vermicomposts Produced from Animal Manures and Sewage Sludge against Phytophthora nicotianae Breda de Haan var. nicotianae

The degrees of suppression produced by vermicomposts produced from cattle manure, sheep manure or horse manure and by vermicomposts produced from sewage sludge were compared in greenhouse experiments. The e€ect of these vermicomposts on the growth and infection of tomato seedlings by Phytophthora nicotianae var. nicotianae was studied. The density of the pathogen and the number of micro-organisms in container media amended with vermicomposts were also analysed. The vermicomposts produced from animal manure signi®- cantly reduced the infection of tomato seedlings by the pathogen. The density of P. nicotianae in media which included these vermicomposts was similar to that in infested peat substrate (control treatment). The vermi- composts from sewage sludge did not protect tomato seedlings against P. nicotianae. They also signi®cantly inhibited growth of the plants as well as decreasing the density of the pathogen in container media. In general the vermicomposts had no e€ect on total number of micro-organisms in potting media compared with con- trol. They only had higher levels of actinomycetes but this did not appear to correspond with their ability to suppress the pathogen.