Characterization of Ampelomyces and its Potentiality as an Effective Biocontrol Agent against Erysiphe cichoracearum DC Causing Powdery Mildew disease in Bhendi (Abelmoschus esculentus (L.) Moench)

摘要

Ampelomyces is one of the most naturally occurring mycoparasitic fungi on powdery mildews. A detailed survey was conducted in major bhendi (Abelmoschus esculentus (L.) Moench) growing regions of Coimbatore district of Tamil Nadu to assess the incidence of powdery mildew disease. The results revealed that disease incidence ranged from 38.04 to 69.54 per cent. From the surveyed areas, ten isolates of Ampelomyces spp were isolated using water agar medium. All the isolates were identified by their morphological characters and microscopic studies. Initially, the mycelia were hyaline and septate in nature over a period of time the color of the matured colonies in various medium turned greyish white to brownish black. Most of the isolates showed radial, flat to the submerged growth pattern. The pycnidia of different isolates of Ampelomyces varied in their shape and were mostly ovoid, pyriform to globose in shape. The size of pycnidia varied from 56.24 - 74.20 x 50.23 - 63.81um. The pycnidial production was found to be more in the isolates viz., AQB1 and AQB7. Pycnidiospores are unicellular and guttulate in shape. An in vitro mycoparasitic activity on detached leaves of bhendi and a detailed microscopic analysis of the interactions between mycoparasite and Eryisphe cichoracearum was documented. Fungicide application is one of the most effective methods to manage powdery mildew disease. However, the frequent use of these fungicide has many disadvantages like the development of resistance to pathogens, residual toxicity and environmental pollution. Hence, we search for an alternative means for disease management. The genus Ampelomyces is considered to be the potential biocontrol agent against the powdery mildew pathogens.