Incidence and Management of Bipolaris oryzae in Rice

The seed lots of 45 rice hybrids and their parental lines were collected from different agroclimatic zones of India. Germination and seed health tests were conducted to evaluate the general seed quality just after the seed lots were received. Eight seed lots were selected for further studies. Seeds were treated with Mancozeb, Thiram, Bavistin and Vitavax, Neem oil, Palmarosa oil, Polykote and Seedkare Orange. Treated seeds were then packed in polythene bags of 700-gauge and kept under ambient condition for six months. Ten seedborne fungi viz. Bipolaris oryzae, Alternaria padwickii, Curvularia lunata, Fusarium moniliforme, Fusarium pallidoroseum, Alternaria alternata, Aspergillus spp., Penicilium spp., and Rhizopus spp. were found associated with these seed lots. Nine categories of seedling abnormality were recorded. Seedlings with decay in shoot and root were encountered most frequently. Mancozeb maintained germination above IMSCS after six months of storage, while other chemicals could not retain germination above IMSCS. Based on inhibition zone test, only Vitavax, Thiram and Mancozeb produced inhibition zones.