Author(s):

Shruthi TH, Gururaj Sunkad, Mallesh SB, ST Yenjerappa and Mahadevswamy

Abstract: The main emphasis of the present study was isolation and antagonistic screening of native Trichoderma isolates against Ceratocystis fimbriata Ellis and Halst. The causal agent of wilt of pomegranate, which cause estimated losses up to 30%. Thirty three native Trichoderma spp. were isolated from the rhizosphere soil of healthy pomegranate plants, identified using morphological and microscopic characteristics and were evaluated for in vitro antifungal activity against Ceratocystis fimbriata by dual culture plate technique. Among the Thirty three isolates maximum per cent inhibition of 93.10 per cent was observed in Trichoderma harzianum (PT-11 isolate) followed by Trichoderma viride (PT-10) and Trichoderma harzianum (PT-4) of about 92.03% and 91.66%, respectively when compared to the all other isolates of Trichoderma spp. Based on the dual culture technique, eleven superior native Trichoderma isolates were selected for elucidating volatile metabolites production by paired plate method. The inhibition of pathogen mycelium varied depending on the Trichoderma species producing volatile metabolites, Trichoderma virense (PT-6) inhibited fungal growth up to 78.84% followed by Trichoderma harzianum (PT -11) of about78.67% and Trichoderma viride (PT-10) of 71.84%. Among superior eleven isolates, PT-6, PT-10 and PT-11 isolates were used for growth promotion and disease control studies in pot culture experiment under greenhouse. The growth of pomegranate seedlings with the antagonist alone and in combination with pathogen was greater than in plants were inoculated with pathogen alone. Among all isolates, T. virense (PT-6) showed higher mean shoot and root length (45.70 cm and 19.04 cm) with lowest disease incidence (20.38%) when compared to highest incidence in pathogen check (41.20%).

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