IMPACT OF PLANTING DATES ON Thrips tabaci Lindeman INFESTATION AND YIELD LOSS IN ONION (Allium cepa L.)

Field experiments were conducted for 4 years during l999-2002 at NRCOG  farm, Rajgurunagar, India, to find out the appropriate date of transplanting for onion to  minimize the yield loss due to thrips infestation. Rabi season plantings (1 November -  15 December) were severely attacked by onion thrips, Thrips tabaci Lindeman followed  by kharif plantings (1 June -1 August). Thrips infestation was highest on crop planted  on 15 - November (70.39/plant) followed by 1 - December planting (59.6/plant). Late  kharif plantings (15 August - 15 October) were comparatively safer from thrips damage.  Onion crop transplanted on 15 - August and 1 - September attracted lowest number ol  thrips (5.48/plant). Highest marketable yield of 44.44 llha was obtained in I5 — September  plantings followed by 1— October. Yield loss up to 46.87% was recorded in rabi season  due to thrips attack. Variations in yields even under low thrips population may be due to  seasonal variations.