Principles in the Development of Biological Control Systems Employing Trichoderma Species Against Soil-Borne Plant Pathogenic Fungi

Abstract

Control of plant pathogens has been accomplished in large part by the use of chemical pesticides. Biological control of these plant pathogens was originally thought to be futile (Garrett, 1956); however, many researchers have shown that certain filamentous fungi are capable of controlling several plant pathogenic fungi. These “biofungicides” have been under investigation for several years. Fungi in the genus Trichoderma have been shown to suppress Pythium spp. (Chet et al., 1981; Harman and Hadar, 1983), Sclerotium rolfsii and Sclerotinia sclerotiorum (Lee and Wu, 1984), Rhizoctonia solani (Elad et al., 1980; Harman et al., 1981; Lewis and Papavizas, 1987), Botrytis cinerea (Tronsmo, 1989), and Fusarium spp. (Sivan and Chet, 1986; 1989) and other pathogens (Cook and Baker, 1983) on various agronomically and horticulturally important plants. Diseases caused by these plant pathogens (e.g., seed rots, damping-off, wilts, fruit rots, and root rots) have been shown to be effectively reduced by Trichoderma. This ability is of major importance because of new restrictions on the applications of chemical pesticides (Harman and Lumsden, 1990). Also, the use of chemical fungicides may eliminate a large range of organisms, some of which may be beneficial to the environment. Biocontrol organisms should be less disruptive than chemical pesticides.