BIOCONTROL OF SOIL-BORNE PLANT-PATHOGENS - CONCEPTS AND THEIR APPLICATION

A few soil-borne plant pathogens have been controlled successfully by commercial formulations of biocontrol agents, but many attempts to dev elop biocontrol inoculants, although promising under experimental cond itions, have met with difficulties in practice. The reasons for this a re discussed in this review, which outlines some of the major findings on the behaviour of microbial inoculants in soil. It is emphasized th at biocontrol also occurs naturally in current agricultural practice a nd can be exploited purposely, but it is vulnerable to disruption by a grochemicals or mismanagement. The future of biocontrol of soil-borne plant pathogens probably lies in integrated (biorational) control syst ems that combine the use of commercial inoculants, where appropriate, with management practices that maintain and enhance the natural biocon trol systems.