First Report of Corynespora cassicola (Berk & M A Curtis C T Wei) causing Leaf Spot on Cowpea (Vigna ungiculata L.) in West Bengal, India

摘要

Vegetable Cowpea (Figna ungiculata) is locally known as 'Barbati' and scientifically named as Vigna ungiculata L. It is an important vegetable crop of West Bengal usually cultivated in medium land as main crop or sometimes as intercrop. The mature seeds of cowpea serve as an important pulse with high protein content. This cowpea crop is severely affected by several diseases caused by fungi, bacteria and viruses. During October, 2014, a new foliar leaf spot disease caused by Corynespora cassicola wasnoticed for the first time on cowpea leaf in Jaguli Instructional Farm, Bidhan Chandra Krishi Viswavidyalaya, West Bengal. The disease appeared as small brown spots with yellow halos, later enlarging & becoming irregular in shape. The disease appeared bothon mature & immature leaves especially from the terminal sides. As the disease progressed, concentric rings in the lesions were observed (Plate 1). The disease became severe (64.4 %) due to prevalence of favourable temperature (22 C to 30.6 C), relativehumidity (68.4% -97.6%) and cumulative rainfall (2.48 mm).