Thirty four isolates belonging to seven Trichoderma species from different geographical locations of India were screened in vitro for their antagonism to Colletotri gloeosporioides and the efficient isolates were further evaluated for their bioefficacy in vivo and in field for control of anthracnose of grapes. In in vitro screening, all Trichoderma isolates overgrew C. gloeosporioides colony. Microscopic examination of hyphal interaction showed plasmolysis of hyphae of C .gloeosporioides by all Trichoderma isolates. The percent inhibition of radial growth of C. gloeosporioides by toxic volatile and non-volatile metabolites produced by different isolates of Trichoderma ranged from 40.8 to 63.6 and from nil to 65.9 respectively. In in vivo trial with 20 most antagonistic isolates, the lowest disease incidence was recorded in leaves treated with T. harzianum 5R obtained from Kodagu, followed by T. hamatum (NAIMCC- 1717) from Andaman and Nicobar islands and T. asperellum (NAIMCC 1769) from Pitchavaram. Survival studies on grape phylloplane with selected 11 isolates indicated that when applied at 5×106 spores per ml the population ranged from 4087.05 to 1185.42 cfu per cm2 on day 5 which further declined by day 15. On foliar application of these eleven isolates in field, lowest PDI was recorded in T. viride (NAIMCC-1817) initially obtained from soil of western Ghats of Kerala. The other isolates which recorded low PDI values were T. harzianum (NAIMCC-1965) obtained from Darjeeling, T. koningii (NAIMCC-1938), T. pseudokoningii (NAIMCC-1775) obtained from Andaman&Nicobar islands and T. harzianum 5R obtained from Kodagu (Karnataka).
Keywords
Colletotrichum gloeosporioides, Trichoderma Spp. Volatile Metabolites, Non-Volatile Metabolites, Lysis and Phylloplane.
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