Suppression of Stem Rot Caused by Sclerotium rolfsii and Growth Promotion of Tomato Plants Using Non-Aerated Compost Teas

The ability of non-aerated compost teas to suppress stem rot, caused by Sclerotium rolfsii (P A Sacc.), and to enhance plant-growth was evaluated. Efficacy of compost extracts on mycelial growth was evaluated using the well-cut diffusion method and the poisoned food technique. Based on the well-cut diffusion method, the compost teas CT3 and CT4 were found to be the most effective against the phytopathogen isolates leading to 68.5 and 56.4% decrease in their mycelial growth, respectively. However, using the poisoned food method, all compost teas exhibited a significant growth inhibitory potential with varying degree depending on their composition and their interaction with pathogen isolates. As for their effects on dry mycelium weight, CT2, CT3 and CT4 teas were the most active leading to 60.8-64.4% decrease in this parameter. Treated on tomato plants, they were found to be the most effective in suppressing necrosis with chitinolytic, proteolytic and lipolytic activities. CT2 was found able to produce the volatile metabolite hydrogen cyanide. The three screened compost teas were found able to produce the indole-3-acetic acid and solubilized the phosphate with positive siderophores production and nitrogen fixation activity. This study demonstrated that CTs can play a promising role in the biological control of plant diseases and the plant growth promotion in organic agriculture.