International Journal of Agricultural Science and Research (IJASR) ISSN 2250-0057 Vol. 3, Issue 3, Aug 2013, 149-150 ÂŠ TJPRC Pvt. Ltd.
A NEW RECORD OF LEAF SPOT DISEASE OF VIGNA UNGUICULATA L. CAUSED BY DRECHSLERA AUSTRALIENSIS (BUGNIC.) SUBRAM. & B. L. JAIN 1966 IN INDIA SOBITA SIMON, ABHILASHA A. LAL & MAYANK KUMAR Department of Plant Protection, Allahabad School of Agriculture, Sam Higgin Bottom Institute of Agriculture, Technology & Sciences, Allahabad Agricultural Institute, Allahabad, Uttar Pradesh, India
ABSTRACT During the monsoon season (July-September 2011) an unusual leaf spot disease was observed on cowpea crop (Vigna unguiculata) under cultivation at Department of Plant Protection, Sam Higginbottom Institute of Agriculture, Technology and Sciences-Deemed to be University (Formerly Allahabad Agricultural Institute) Allahabad, Uttar Pradesh. The infection spots on the leaves started at the tip and gradually moved towards the centre later, small irregular spots mostly scattered, dark-brown with clear margin appeared (Figure 1). Critical examination of sections of such spots in the laboratory revealed the presence of a fungus with conidia which were slightly curved, broadly fusi form or obclavate fusoid, pale or mild golden brown,smooth,3-5 pseudo- septate  The fungus growth was fast with black coloured fluffy mycelium (Figure 3).On the basis of cultural and morphological characters the fungus was identified as Drechslera sp. Further, the culture of the fungus was sent to Indian Type Culture Collection, IARI, New Delhi The fungus was identified as Drechslera australiensis (Acc No.8854.12). And the culture is submitted at ITCC, New Delhi.
KEYWORDS: Cowpea, Vigna unguiculata, Leaf Spot, Drechslera australiensis PATHOGENECITY TEST Pathogenecity of the fungus was confirmed . The suspension of the fungus was poured on the surface of moist soil in a pot and mixed in the top two cm layer of the soil and the seed were sown. The pots were kept in a polyhouse. The symptoms started appearing 25 days after sowing .D. australiensis was re-isolated from infected seedlings (Figure 4). Control plants did not show any symptoms. Search of relevant literature  revealed that leaf spot on cowpea caused by D.australiensis has not been reported earlier and this is a new record.
Ainsworth GC.1961. Dictionary of the fungi . Can J. Microbiol. 34:157-161.
Sunder S, Singh R. and Dodan DS 1993. Adaptation of Rhizoctonia solani isolates of four anastomosis groups of carbendazim and its effect on their pathogenic behaviour. Ind. J. Mycol. Pl. Pathol. 23(3):255-259.
Motlagh MR and Kaviani B. 2008. Characterization of new Bipolaris spp.: the causal agent of rice brown spot disease in the North of Iran. Int J. Agri. Biol. 10:638-642.
Sobita Simon, Abhilasha A. Lal & Mayank Kumar
Figure 1: Diseased Leaf of Cowpea
Figure 2(B) :Conidia of D. australiensis
Figure 3: Fungal Mycelial Growth on PDA Plate
Figure 2(A):Conidiophore and Conidia of Drechslera australiensis
Figure 2(C) :Mycelium of D. australiensis
Figure 4 :Pathogenecity Test
During the monsoon season (July-September 2011) an unusual leaf spot disease was observed on cowpea crop (Vigna unguiculata) under cultivati...