Study on Impact of Sowing Dates on Rice Leaf Folder Cnaphalocrocis medinalis (Guenee) in Direct Seeded Rice

A field experiment to study the impact of sowing dates on Rice leaf folder in direct seeded rice was conducted at Agricultural College Farm, Bapatla during kharif, 2021. Early planted rice crop had lower pest than later transplanted rice. Various dates have a significant impact on the occurrence of biotic stress, particularly insect pests. To identify suitable plating dates to minimize the leaf folder infestation in paddy the following experiment was conducted. Sowing was done at four different dates with 10 days interval which were taken as treatments each replicated with five times and the data has also been correlated with light trap data. The mean per cent damage ranged from 9.44 to 16.64 %. Highest infestation (16.64 %) was observed in last date of sowing and least damage (9.44 %) was observed in first date of sowing. Correlation analysis of light trap catch data shown a positive correlation with morning (r = 0.373) and evening (r = 0.186) relative humidity while a negative correlation with maximum (r = - 0.182), and minimum (r = - 0.017) temperatures and rainfall (r= - 0.154). Multiple Linear Regression (MLR) of trapped adult number and climatic conditions at different sowing dates revealed that weather parameters contributed to the variation in moth number trapped in light trap by 35.4 per cent in first date of sowing, 42.2 per cent in second date of sowing, 59.6 per cent in third date of sowing, and 50.7 per cent in fourth date of sowing. Yield ranged from 3632 kg ha-1 in last date of sowing to 5156 kg ha-1 in first date of sowing.