PHTOPHTHORA DRECHSLERIJ براي كنترل بيولوژيك بيماري بوته ميري جاليز TRICHODERMA ارزيابي جدايه هاي

Evaluation of Trichoderma isolates for biological control of Phytophthora drechsleri in glasshouse

Trichoderma harzianum 139, T. harzianum M, T. virens DAR 74290, T: viride and Trichoderma sp. 96 were evaluated for biological control root of and stem rot of cucurbit caused by Phytophthora drechsleri in vitro and in galsshouse. Dual culture, cellophane overlays technique and volatile metabolites were used in vitro assay. Greenhouse experiments were carried out to test Trichoderma isolates against P. drechsleri by seed and soil treatments. Results of in vitro assay indicated that, all tested isolates of Trichoderma inhibited the growth of P. drechsleri. Mycelial inhibition varied between isolates of Trichoderma and ranged from 17.82 to 82.65 in dual culture and from 15.96 to 100% using the cellophane overlay methods. Cell-free metabolites of T. virens DAR74290 completely inhibited the growth of P. drechsleri in vitro and appeared having fungicidal properties. Mycelial growth of P. drechsleri was reduced 11-50% by volalite metabolite of Trichoderma isolates throughout 120 hours inoculation. Survival of seedling in pots treated with Trichoderma only or Trichoderma + pathogen was significantly (P< 0.001) greater than inoculated plant with the pathogen only. Population of antagonists and pathogen were estimated (cfulg) in potting mix 10 and 40 days after planting. The population (cfu/g) of pathogen and antagonist were fixed during experiments.