Evaluation Of Strptomyces Strains As Biocontrol Agents For Cantaloup Wilt, (Phytophthora Drechsleri)

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Abstract

Thirteen strains of Streptomyces were evaluated as a potential biological agent for control of cantaloup mot rot that caused by P. drechsleri. Eight strains of Streptomyces were obtained from soil surrounding the roots of cucurbit plants in Varamin area and five strains were obtained from soil surronding roots of capsicum in glasshouse. Dual culture and cellophane overlay technique were used for in vitro assay. In dual culture and cellophane overlay techniques, all strains of Streptomyces inhibited the growth of P. drechsleri. The inhibition rate varied among strains of Streptomyces and ranged from 33.01% to 93.07% in dual culture and frol1'l36.18% to 100% in the cellophane overlay method. Adding a mixture of 13Streptomyces strains (5 g) prepared in 1 kg wheat bran to soil infested with mixture of six P. drechsleri isolates increased seedling survival by 43.07% (P < 0.05). Also seed treatment with 7.3 x 106 cfu per seed increased plant stand by 50.21% (P < 0.01). Average population of Streptomyces in potting mix decreased at a uniform rate.

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