حمیدرضا علیزاده

Sclerotinia sclerotiorum is one of the most important pathogenic fungus of cucumber throughout the regions were cultivated. Jiroft and Kahnuj areas, with 600 ha of greenhouse and more than 3000 ha of short tunnel cucumber farms, are the major regions of cucumber cultivation in Iran. Biological control has recently considered as an efficient strategy to manage plant diseases. Present study was performed to evaluate the biological control of the disease, and antagonistic activity of fluorescens pseudomonad against S. sclerotiorum. More than 80 isolates of Pseudomonad were isolated from rhizosphere of cucumber and purified on S1 selective medium. Antagonistic activities such as inhibition zone diameter, volatile metabolits and protease and Hydrogen cyanid production were examined. As preliminary Results, using dual culture method,15 isolates showed remarkable inhibitory activity against S. sclerotiorum which amongst, 19C, 24A, 33B, and 33C isolates having more effect by producing 13, 12, 23 and 7 mm inhibition zone. In addition, the effects of volatile compounds were evaluated on preventing mycelia growth, protease and HCN protection tese. Based on results, isolates 19C, 24A, 33B, 33C, had the most inhibitory effects on mycelial growth (87%, 82%, 80%, 82%, respectively). All isolates were capable protease (19C and 33C had the most protease activity) and isolates 33B and 33C hav e also the ability of HCN production. Molecular identification and antagonistic effects of mentioned isolates against Sclerotinia stem rot under greenhouse and field conditions are underway.