E. Bakhshi - Department of Plant Pathology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Islamic Republic of Iran.
N. Safaie - Department of Plant Pathology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Islamic Republic of Iran.
M. Shamsbakhsh - Department of Plant Pathology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Islamic Republic of Iran.

Seventy five bacterial strains were isolated from cucurbits rhizosphere and examined for antagonistic activities against Macrophomina phaseolina isolate ۴۴, the causal agent of melon charcoal root rot disease. The results of screening strains including B۲, B۱۱, B۱۲ and BKN showed high potential of antagonistic activities against the pathogen in laboratory experiments. Inhibition of mycelial growth varied from ۵۴.۳ to ۶۲.۲۲%, ۳۹.۴۳ to ۵۴.۸۲%, ۷۸.۵۲ to ۱۰۰%, and ۶۴.۴۵ to ۸۸.۸۹% in dual culture, volatile metabolite, antibiotic production, and cell free culture tests, respectively. In greenhouse experiment, seed treatment with strain B۲ significantly (P= ۰.۰۱) controlled the disease by increasing plant growth indices including height, shoot and root fresh weight, shoot and root dry weight by ۳۷.۹۸, ۳۶.۲۷, ۳۲.۹۷, ۳۴.۴۴, and ۳۰.۳۹%, respectively, as compared to the control. The biochemical and physiological tests as well as gyrA sequence confirmed these four strains as Bacillus amyloliquefaciens. Results indicated that strain B۲ could be an important new biological control agent for charcoal root rot disease of melon.

Antagonistic activity, Biological control, Cucurbits Macrophomina phaseolina, Rhizosphere., کنترل بیولوژیک, ریزوسفر, کدوییان, ایران, قارچ Macrophomina phaseolina