Investigation on The Ability of Thrichoderma spp. Existent in The Soil of Cucumber Greenhouses of Yazd Province to Control Fusarium Wilt Agent in Vitro Condition

Biocontrol of plant diseases is a significant indicator for the production of organic agricultural products. In order to find suitable native Trichoderma spp., for the purpose of biological control of Fusarium wilt of cucumber, samples were taken from the greenhouse soil of major areas of greenhouse cucumber cultivation in Yazd province. After the processes of separation and purification, and based on morphological and molecular characteristics, native Trichoderma spp. isolates were identified. Twenty Trichoderma isolates were identified which belonged to T. harzianim and T. atroviride species. The results of analysis of variance of dual-culture experiments and the test data relating to the production of volatile metabolite substances showed that native isolates inhibited the F. oxysporum mycelium growth (α=1%). The results indicated that the rapidity of growth in native isolates was notably higher than that of Fusarium wilt agent, so that after some days they covered its colonies. Besides, while having occupied the place of growth and using the needed nourishment, they grew on pathogen mycelium, and through producing volatile substances they inhibited the formation of pathogen mycelium. The results showed that T. atroviride (Ta8) isolate had the maximum growth inhibition effect.