Characterization of indigenous soil isolates of aspergillus niger aggregate and development of their commercial formulations for the management of wilt disease complex of chickpea and tomato caused by fusarium spp. and meloidogyne incognita

Abstract

Chickpea is a major source of human food and the world s third most important pulse crop after beans and peas. Similarly tomato is considered as poor man s orange , a vitamin C rich vegetable and is eaten freely hroughout the world. Chickpea production in India has declined considerably and tomato production has been limited due to the regular occurrence of wilt caused by Fusarium oxysporum f. sp. ciceri and F. oxysporum f. sp. ycopersici, respectively and root-knot caused by Meloidogyne spp. and the esulting fungus-nematode wilt disease complex. Annual yiel losses to chickpea and tomato from the wilt vary from 10-15% in India. The disease under specific conditions may cause much greater losses or may destroy the entire crop in a field or area. Root-knot nematodes have been reported to reduce the yield of chickpea and tomato by 9-40% and 24-61% in India. The concomitant situation involving Meloidogyne spp. and Fusarium spp. leading to the development of wilt disease complex is, however, more damaging. The fungus-nematode wilt complex is one of the major constraints in the production of chickpea and tomato in India, and many growers have given up cultivation of these crops because of the disease complex. Management of wilt or root-knot is not an easy task, it becomes further difficult for wilt isease complex because of multi-pathogenic nature of the disease. When a pesticide is applied, it is targeted either against the wilt fungi or root-knot nematode, consequently the disease remains relatively unchecked. In view of lesser effectiveness of chemicals, high cost of application and adverse effects, biological control offers potential substitute for the management of newlinewilt, root-knot and the wilt complex of chickpea and tomato. Present study was undertaken with an objective to identify and characterize indigenous fficient isolates of Aspergillus niger for effectiveness against wilt (F. oxysporum f. sp. iceri/lycopersici), root-knot (M. incognita) and the wilt isease complex (F. oxysporum f. sp. ciceri/lycop