STUDIES ON INCIDENCE OF MAJOR LEPIDOPTERAN PESTS IN RICE AND THEIR MANAGEMENT WITH BOTANICALS AND NEW INSECTICIDES
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Date
2022-08-17
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guntur
Abstract
An experiment entitled as “Studies on incidence of major lepidopteran pests in rice and their management with botanicals and new insecticides” was conducted at Agricultural College Farm, Naira, during rabi, 2020-21.
The incidence of major lepidopteran pests with abiotic factors was recorded at an interval of 5 days beginning at 15 days after transplantion on 10 randomly selected hills. While for management, when the yellow stem borer and leaf folder infestation was observed to reach Economic Threshold Levels, pretreatment count was recorded one day prior to the application of treatments and post treatment data was taken at 1st , 3rd , 7th and 12th day after spraying from ten randomly selected hills.
The data pertinent to the incidence revealed that the months of March and April were favorable for the occurrence of yellow stem borer and leaf folder in rice. The peak incidence of Scirpophaga incertulas (23.50% dead hearts) was observed during 12th standard week (third week of March) and multiple regression analysis (dead hearts) showed that the weather parameters altogether can cause variation upto 49.5 per cent (R2 = 0.495). The results from correlation analysis between weather parameters and yellow stem borer showed non siginificant positive correlation with maximum temperature (r = 0.315) and morning relative humidity (r = 0.222). Whereas minimum temperature (r = -0.179), evening relative humidity (r = -0.307) and rainfall (r = -0.313) showed non significant negative correlation. However, a significant positive correlation was observed between minimum temperature (r = 0.693), rainfall (r = 0.515) and per cent white ear head incidence.
The peak incidence of Cnaphalocrocis medinalis (24.56% leaf damage) was observed during 13th standard week (last week of March) and multiple regression analysis showed that abiotic factors were able to cause variation in the incidence of leaf folder to an extent of 36.7 per cent (R2 = 0.367). The correlation analysis between leaf folder and weather parameters revealed that, maximum temperature (r = 0.372), mimimum temperature (r = 0.042) and morning relative humidity (r = 0.059) showed non significant positive correlation where as evening relative humidity (r = -0.134) and rainfall (r = -0.324) showed non significant negative correlation.
The studies on management of major lepidopteran pests with insecticides revealed that, Chlorantraniliprole 18.5 SC @ 0.4 ml/l was most effective against yellow stem borer and leaf folder followed by Flubendiamide 480 SC @ 3.0 ml/l and Spinetoram 11.7 SC @ 1.5 ml/l.
The highest B: C Ratio of 2.44: 1 was obtained under Chlorantraniliprole 18.5 SC @ 0.4 ml/l by recording a yield of 5940 kg ha-1 with 86.60 per cent increase in yield over untreated control (3183 kg ha-1).
Description
STUDIES ON INCIDENCE OF MAJOR LEPIDOPTERAN PESTS IN RICE AND THEIR MANAGEMENT WITH BOTANICALS AND NEW INSECTICIDES