Asian Research Journal of Current Science

The research was conducted to study the morphology and pathogenicity of Sclerotium rolfsii isolates, to evaluate the responses of tomato varieties to collar rot disease, and to select the effectiveness of Trichoderma isolates in controlling this disease. The experiments were laid out in completely randomized design and carried out at the Department of Plant Pathology, Yezin Agricultural University (YAU), Myanmar during February, 2024 to February, 2025. Total seven isolates of S. rolfsii were obtained from the tomato fields of seven villages in Zeyarthiri Township, Nay Pyi Taw Union Territory and named the isolates as SR1, SR2, SR3, SR4, SR5, SR6 and SR7. Their pathogenicities were tested on the tomato variety, Kyaukme Gaung Seine. Except SR7 isolate, other six isolates caused 100% seedling mortality. After inoculation of ten tomato varieties with the S. rolfsii isolate; SR5, the variety; Red Diamond115 was moderately susceptible while the rest were susceptible to the disease. According to the molecular characterization based on PCR with species specific primers, HAR220FP5 and HAR220RP5 for Trichoderma harzianum and VIRI900FP7 and VIRI900RP7 for Trichoderma viride, the commercial Trichoderma isolate (DAR-Tri.sp) was identified to be T. harzianum and the four Trichoderma isolates from YAU were diagnosed to be T. viride. When the effectiveness of Trichoderma isolates on mycelial growth of S. rolfsii were tested, YAU-Tri.sp4 showed the highest inhibition percent among the tested five Trichoderma spp.. Also, it had promoted tomato plant growth and controlled the collar rot disease (84%) compared to Trichoderma uninoculated plants. Therefore, YAU Trichoderma isolate, YAU-Tri.sp4 could be used as a potential biocontrol agent for the management of tomato collar rot disease.