Effect of Nitrogen fertilizer, weed control and seed rate on incidence and severity of narrow brown leaf spot in rice cultivation under the dry zone of Sri Lanka

Narrow Brown Leaf Spot (NBLS) caused by Cercospora janseana is a common disease of rice causing severe yield loss. In order to identify the factors favourable for disease development under field conditions, a study was carried out during the 2017/2018 Maha and 2018 Yala seasons. Effects of mineral N fertilizer, weed control, and seed rate on the incidence and severity of NBLS disease were determined. Two levels of mineral N, i.e., Department of Agriculture, Sri Lanka (DOF) recommended level and half of the DOF level were used with weedy and weed-free conditions, under four different seed rates, 100 kg/ha, 125 kg/ha, 150 kg/ha and 175 kg/ha. NBLS incidence was significantly higher (p