Use of Agricultural and Municipal Organic Wastes to Develop Suppressiveness to Plant Pathogens

Abstract

Research on biological control and natural suppression of fungal plant pathogens has significantly increased worldwide during the last decade (Janisiewicz, 1988; Park et al., 1988; Shimshoni et al., 1988; Sztejnberg et al., 1988). Although research has often concentrated on individual microorganisms, the use of complex organic substrates has been shown to be effective in protecting plant health (Hoitink and Kuter, 1986; Mandelbaum et al., 1990; Spring et al., 1980). Composted organic material such as plant debris and animal manure have been used for more than 2,000 years to improve soil fertility. It is known that there is a close connection between soil-borne plant disease occurrence and the organic matter content in the soil (Lumsden et al., 1983b). Balanced nutrition with compost has been considered fundamental for maintaining health through its influence on plant resistance mechanisms (Chaboussou, 1985). The importance of composted organic material in suppressing soilborne pathogens has often been demonstrated (Hadar and Mandelbaum, 1986; Hoitink et al., 1977; Hoitink and Fahy, 1986; Lumsden et al., 1983a; Spencer and Benson, 1982). Most of these studies pointed out a suppressive mechanism of action. Hoitink (1980) and Reinmuth and Bochow (1960), however, showed that composted organic material may promote disease. In most disease-suppression instances, stimulation of antagonistic microorganisms in the rhizosphere or induced defence reactions in the host plant tissue are considered responsible for the beneficial effects (Harman and Lumsden, 1990).