Emergence of brown leaf spot of rice in Punjab and efficacy of some chemicals against it

Brown spot caused by Drechslera oryzae (Breda de Haan) Subram and Jain is an emerging disease of rice in Punjab causing significant yield losses. A regular survey of rice crop was conducted during 2000 to 2005 Kharif seasons in the state. The severity of disease was observed to be highest during kharif 2002. Mean disease severity was maximum (28.9%) in the Gurdaspur district while it was minimum (13.9%) in Sangrur district on different varieties. PR 106, PR 114 and PR 116 were found to be relatively more susceptible to brown spot as compared to PR 111, PR 113, PR 115 and PR 118 under artificial inoculation conditions. Efficacy of some new fungicides against brown spot was evaluated under artificial inoculation conditions during Kharif 2003, 2004 and 2005 on variety PR116. Armure 30EC @ 0.1 per cent was the most effective chemical as it significantly reduced the mean disease severity to 5.18 per cent and increased grain yield to 6153 Kg/ha as compared to the untreated control where mean disease severity and grain yield was, 40.18 per cent and 4593 Kg/ha, respectively. Tilt 25EC @ 0.1 per cent and RIL FA200SC @ 0.25 per cent were the next most effective fungicides with mean disease severity of 8.47 per cent & 8.71 per cent respectively followed by Contaf 5EC @ 0.2 per cent (13.35%). Sheathmar 3L, Saaf 75WP and Antracol 70WP were comparatively less effective chemicals in controlling brown spot. However, Kitazin 48EC and Baycor 25WP were the least effective fungicides in controlling brown spot of rice.