CONTROL OF WOOD DECAY BY TRICHODERMA (GLIOCLADIUM) VIRENS - II - ANTIBIOSIS

Trichoderma (Gliocladium) virens has shown good antagonism against dec ay fungi in agar medium and in wood blocks. Gliotoxin produced by T. v irens is associated with biocontrol of some plant diseases, but its im portance to biocontrol of wood-attacking fungi is unknown. We investig ated the ability of gliotoxin-producing [GLT+] isolates of T. virens a nd gliotoxin-deficient [GLT-] mutants of T. virens to inhibit growth o f wood-attacking fungi in agar medium and to prevent decay in wood. Th e brown-rot fungi Postia placenta and Neolentinus lepideus and the whi te-rot fungi Trametes versicolor and Phlebia brevispora were completel y inhibited by the GLT+ isolate and the GLT-mutants in agar medium. Th e GLT+ isolate also completely inhibited the growth of the brown-rot f ungus Gloeophyllum trabeum and the white-rot fungus Irpex lacteus, but the GLT-mutants caused lesser inhibition. The GLT+ isolate and GLT-mu tants were ineffective in preventing growth of mold fungi, but both in hibited stain fungi in dual agar culture. Pretreatment of wood blocks with the GLT+ isolate or GLT-mutant prevented decay by the brown-rot f ungi. Although the GLT+ isolate prevented decay by the white-rot fungi , the GLT-mutants did not. G. virens [GL-21] was grown on a sulfur-con taining medium at pH 3.5 to enhance antibiotic production in culture f iltrates. However, inhibition of growth of decay fungi on agar medium containing culture filtrates was not enhanced. Decay was reduced in bl ocks treated with the culture filtrates but was not completely stopped . The filtrates were also ineffective in preventing growth of mold and stain fungi on wood.