Detection and diagnosis of leaf spot of mungbean leaf spot bacterium from seeds and its management

Abstract

Mungbean (Vigna radiata) crop cv. Merta local in Nagour, Rajasthan suffered from bacterial leaf spot during kharif, 2012. Bacterium Xanthomonas axonopodis pv.vignaeradiatae was isolated and pathogenicity was proved on a one month old plants. Symptoms were observed on all above ground parts of plants. Brown necrotic spots were developed on leaves with shot holes. Stems had elongated, dark brown spots with cracks. Small, deformed seeds were developed on dark brown spotted pods. Leaf blight and mortality was not seen. Bacterium was detected on five agar media. Kado and Heskett’s medium was best followed by yeast extract glucose chalk agar and modified Peterson’s media. Higher infection was seen on seeds of artificially inoculated plants. All fungicides, antibiotics, bioagents and botanicals were able to inhibit bacterial growth and reduce disease in pots with increased seed germination. In three pot trials, antibiotics were superior over bioagents, fungicides and botanicals. Minimum disease and highest fresh plant weight of mungbean was obtained by Labistryn followed by Streptocycline and Bacterinol when used as seed treatment + two foliar sprays. Blitox, Pseudomonas fluorescens and neem oil were better in their groups against the disease.