A Method to Screen Trichoderma Isolates Against Soil Sclerotial Fungi and Armillaria Root Rot

Naturally occurring or mutated strains of soil microorganisms should be assessed for their biocontrol abilities in experimental conditions that closely match those of the natural environment (Whipps and Budge, 1990). Screening for isolates able to control soil fungi should be carried out in natural soils with the target parasite and the antagonist being introduced together. Moreover, the parasite should be tested for aggressiveness (on a test plant) or at least for viability (Lumsden and Lewis, 1989). This method is time and space consuming and impractical when strains are being compared. However, simplified methods can be used when the main mechanisms of antagonist action have been defined. For instance, fungal wall lysis and saprophytic competitiveness have been shown to be important prerequisites for the control of sclerotial soil by Trichoderma (Adams, 1989; Davet, 1987; Elad et al., 1982).