Evaluation of Some Trichoderma harzianum Isolates for the Management of Soilborne Diseases of Brinjal and Okra

Present study investigated the efficacy of 6 Trichoderma harzianum isolates against damping off and wilt diseases of brinjal and okra caused by Fusarium oxysporium (FO) and Pythium aphanidermatum (PA), respectively in order to get more effective isolates for disease management. Isolated pathogens from brinjal were named as Fob and Pab and from okra Foo and Pao for F. oxysporum and P. aphanidermatum, respectively. In vitro analysis revealed that T. harzianum isolates inhibited the radial growth of both pathogens and isolate Th-Sks was most effective with 78.44 and 74.16% growth inhibition of Fob and Pab, and 78.19 and 78.11% of Foo and Pao, respectively. Production of volatile and non-volatile metabolites by isolate Th-Sks was more aggressive in mycelial growth inhibition of all test pathogens than that of other isolates. Isolate Th-Sks had highest suppression efficacy i.e. 95.92 and 98.93% for Fob and Pab, 96.43 and 93.33% for Foo and Pao under glasshouse conditions, 96.18 and 95.73% for Fob and Pab, and 94.66 and 96.18% for Foo and Pao in the field conditions, respectively. Additionally, seed treatment of brinjal and okra with isolate Th-Sks gave a significant stimulatory effect on plant height (brinjal 52.9 cm; okra 110.5 cm) and increased fruit yield (brinjal 328.3 g; okra 294.6 g) in comparison to other isolates and control sets during field trials. Thus, it is concluded that isolate Th-Sks can be used as biocontrol agent for management of wilt and damping off diseases of okra and brinjal after multilocation trials.