Abstract
A laboratory study was conducted to evaluate the ability of three locally isolated Trichoderma spp., T. longibrachiatum UAMH7955 (Lib1), T. harzianum ( Lib2) and T. longibrachiatum UAMH7956 (Lib3) and two commercial T. harzianum ATCC 20847 (T22), T. atroviride ATCC 74058 (Tp1) to antagonize Sclerotinia sclerotiorum at 20, 25°C. Results showed the effect of Trichoderma isolates in the inhibition of mycelium growth and sclerotia formation of S. sclerotiorumat 20, 25°C. The highest numerical inhibition rate 55% and 45% of S. sclerotiorum mycelium growth was caused by Lib1 and Lib3 at 25°C, respectively. While, similar antagonistic range 30 -40% was reported for all Trichodema isolates At 20°C, on the other hand, Lib1, Lib2, Lib3, and T22 were able to inhibit sclerotia formation at 25°C compared to Tp1. The lowest inhibition of sclerotia formation 60% and 49.7% was reported for Lib1 and Tp1 treatments at 20°C. Significant inhibition rate (71, 77.7, 91, 91%) was caused by Lib2, T22 at 20 and 25°C, respectively. Effect of the antagonistic fungi on germination of pea seeds (local variety) pretreated with Trichoderma isolates and seedlings infection rate after 12 and 24 h. was also tested, 96.9% of seed germination treated with Lib1, Lib2 was reported and 76% for Tp1. Lower seedlings infection rate by S. sclerotiorum was also reported. Key words: Biological control, Mycoparasitism, Trichoderma, Sclerotinia scleroti