Suppressiveness of municipal solid waste composts to plant diseases induced by soilbome pathogens

Abstract

Composts produced from municipal solid wastes (MSW) or other organic wastes have been demonstrated to present suppressive effects towards numerous soilborne plant pathogens (Hoitink and Grebus, 1994) such as Rhizoctonia sp. (Mathot, 1987), Rhizoctonia solani, Pythium ultimum (Schuler et al., 1989), and Mycosphaerella pinodes (Schuler et al, 1993). In the experiments presented here, we studied the suppressiveness of MSW-composts to four diseases induced by soilborne pathogens: soft and dry rots of potato tubers, clubroot of Crucifers and Fusarium wilt. Soft rot of potato tubers caused by Erwinia carotovora subsp. atroseptica, as well as dry rot caused by Fusarium roseum var. sambucinum, appear during tuber storage. They originate from propagules present at the tuber surface contaminated in soil during the growing period. Suppressiveness of a soil (or a compost) affects rot development during tuber storage (Tivoli et al., 1987). Since the main way of pathogen transmission for soft rot to the tubers is soil water, we studied the suppressiveness of compost water extracts. Clubroot disease of Crucifers causes root galls on colza, cauliflower and various cabbages. Its causal agent, Plasmodiophora brassicae, can survive in soil as resting spores for many years. Attempts have been reported to control this disease with composted bark or wool waste (Kinoshita et al., 1988) or with a cattle manure lumbricompost (Szczech et al., 1993). Fusarium wilts, caused by formae speciales of Fusarium oxysporum, affect a large range of cultivated plants. A variety of bark composts as well as pig slurry compost appeared to be suppressive to these diseases (Filippi and Pera, 1989; Reisinger et al., 1992; Trillas-Gay et al., 1986). The purpose of our work was to compare the suppressiveness of an MSW-compost and an MSW-lumbricompost to the four diseases described previously.