Field Evaluation of Foliar Insecticides Against Rice Caseworm, 1980

Abstract

Abstract Fourteen days after transplanting, field plots(2 m2) were hand infested with greenhouse-reared second instar larvae at 4 larvae/hill. The next day insecticides were applied as foliar sprays at 0.75 kg ai/ha in a volume of 300 l/ha. The IRRI (Los Banos, Laguna, Philippines) trial (randomized complete block design) was replicated 4 times over time. Each plot surrounded with levees was encircled with plastic sheeting to prevent interplot larval movement. Two replications planted April 4 were sprayed April 18 and two replications planted May 26 were sprayed June 9. Climatic data for the two 10-day periods after each spraying were: rainfall 0 and 8.2mm, RH 79% and 83%, mean daily maximum temperature 32° and 32° C, and mean daily minimum temperature 23 and 25° C, respectively. Caseworm damage was scored immediately before spraying and 5 and 10 days later. A tiller was scored as damaged if at least one leaf was cut by caseworm feeding. The leaf scraping index (1-9) was based on percent leaf area removed: 1 = 0%, 3 = 1-10%, 5 = 11-25%, 7 = 26-50%, 9 = 51-100%.