Division of Entomology, College of Agriculture, Andhra Pradesh Agricultural University, Rajendranagar, Hyderabad-500 030 (India).
*A part of approved M.Sc (Ag.) thesis submitted by D. Sridevi to Andhra Pradesh Agricultural University, Hyderabad (India).
Persistence of carbofuran 3G in different soil types, viz., red sandy loam, black sandy loam, clay, and alkaline sandy clay loam in relation to control of brown plant hopper (BPH), Nilaparvata lugens (Stal), was studied in greenhouse. Bioefficacy studies involved the release of BPH nymphs on TN-(1) rice plants at 1, 5, 10, 15, 20 and 25 days after treatment (DT) with carbofuran @ 1kg a.i./ha. More than 50 per cent mortality was recorded in red and black sandy loam soils till 5 DT, while in clay and alkaline no appreciable mortality was recorded. Analysis of plant, water and soil carried out simultaneously for total carbofuran residues showed that in plants at 5 DT, carbofuran was non detectable, while 3-keto carbofuran was a major metabolite. Maximum persistence was recorded in plants grown in red sandy loam. However, persistence was maximum in water from alkaline soils. In soils, 3-keto carbofuran was non-detectable in clay at 0 DT, while in other three soil types it was non-detectable from 1 DT. Persistence of chemical in the four soils had less variation and ranged from 4.7 to 5.37 days.
