Morphological Characterization and Biological Management of Gloeosporium ampelophagum (Pass.) Sacc Causing Anthracnose of Grapes in India

Abstract

Grape an important fruit crop, has been found to face a serious threat due to anthracnose disease. The disease on leaves appeared as small irregular dark brown lesions, which later developed greyish centre with dark brown margins that eventually dried and dropped resulting in peculiar shot hole appearance. On twigs (vines) the disease initially appeared as light brown circular lesion which on elongation became elliptical and developed sunken ashy grey centre. Coalescing of numerous such lesions culminated in canker formation. Berry symptoms were initiated as circular reddish brown lesions, which later coalesced, resulting in shrivelling and mummification of berries. The pathogen was isolated on potato dextrose agar medium and its pathogenicity was proved. The fungus produced circular, cottony colony with light green centre and creamish margins which later turned olive green with radial furrows. Acervuli and conidia were formed 10 days after incubation at 25±2 oC.  Conidia (6.21 × 3.87μm) were oblong and hyaline to brownish in colour. Based on its colony characters, morphological characters and by comparing with authentic descriptions as well as through pathogenicity the pathogen causing anthracnose disease of grapes was identified as Gloeosporium ampelophagum (Pass.)Sacc.  The fungus showed highest mycelial sporulation of 0.81×106/ml on oat meal agar with a pH 6.5 at 25-30 oC. Among the bio-agents screened, Trichoderma harzianum exhibited maximum inhibition in mycelial growth of 62.53 per cent that can be effectively used for the management of the disease.