Prevalence and management of spot blotch (Cochliobolus sativus) of barley (Hordeum vulgare L.) in eastern India

Blighted samples of barley leaves collected from eastern Uttar Pradesh, Bihar and Jharkhand during 2003-06 revealed Bipolaris sorokiniana (Sacc. in Sorok.) Shoem. causing spot blotch, Drechslera graminea (Rab. ex Schlecht) Shoem. causing stripe disease, and Drechslera teres (Sacc.) Shoem. causing net blotch, with 63%, 12% and 11% frequency of isolation, respectively, as major foliar blight pathogens. Field trials conducted during 2003-04 and 2004-05 established 3 sprays of propiconazole (Tilt) 25 EC @ 0.75 litres per hectare at maximum tillering, boot leaf and sort dough stages as most effective and economic spray on highly Susceptible barley variety RD 2503. It resulted in 42.56% disease severity, 3.73 tonnes per hectare yield and Rs. 18939 net return, 79.62% yield loss avoidance, and 6.68 benefit: cost ratio. Under artificial spot blotch epiphytotics., NDB 1173 was found the best barley variety with moderately resistant disease reaction and 3.25 tonnes yield per hectare. Jyoti with 3.02 tonnes yield per hectare was at par with it with moderately susceptible reaction. Evaluation of 205 recently generated barley genotypes against spot blotch pathogen, revealed that only 86 genotypes showed stable moderately resistant reaction.