Bio-efficacy of trichoderma isolates and bacillus subtilis against root rot of muskmelon cucumis melo l. caused by phytophthora drechsleri under controlled and field conditions

Root rot of muskmelon caused by Phytophthora drechsleri (Tucker) is considered the most important disease limiting muskmelon production in Pakistan. In this study, three molecularly characterized isolates of Trichoderma (T. harzianum HK, T. harzianum HM, T. asperellum TH) and phenotypically characterized isolate of Bacillus subtilis were evaluated against P. drechsleri under laboratory conditions. The different antagonism assays such as, dual culturing, non-volatile, volatile metabolites and field conditions were tested. The results showed that all tested isolates of Trichoderma and Bacillus subtilis significantly (p<0.001) inhibited the mycelial growth of the pathogen. In all dual cultures, T. asperellum TH showed maximum mycelial inhibition followed by T. harzianum HK, T. harzianum HM and Bacillus subtilis. Non-volatile metabolites were more effective against pathogens than volatile metabolites. Under field conditions, percent disease incidence was decreased while percent plant survival, dry root and shoot weight significantly (p<0.001) were increased by the application of To (combination of all tested Trichoderma isolates and B. subtilis) followed by T. asperellum TH during both growing seasons. It is suggested that bio-control agents can be used for the sustainable management of root rot of muskmelon. (Cucumis melo L.) (author)