A selective medium for improving quantitative isolation ofTrichoderma spp. from soil

ATrichoderma-selective agar medium (TSM) was developed for quantitative isolation ofTrichoderma spp. from soil. Selectivity was obtained by using chloramphenicol as a bacterial inhibitor, and pentachloronitrobenzene, p-dimethylaminobenzenediazo sodium sulfonate and rose-bengal as selective fungal inhibitors. The TSM also contains a low concentration of glucose which still allows relatively rapid growth and sporulation ofTrichoderma, enabling convenient and rapid identification ofTrichoderma colonies. All the 15Trichoderma isolates tested formed colonies and grew well on this medium. Recovery ofTrichoderma from artificially inoculated soils was high and was not affected by soil type or by other microorganisms. A positive correlation was observed betweenTrichoderma added to soil and counts ofTrichoderma colonies on TSM plates. When combined with a soil pellet sampler, the selective medium was also used successfully for recovery of the indigenousTrichoderma population of natural soils.