OPTIMAL TIME FOR INSECTICIDE APPLICATIONS TO REDUCE THE ONION THRIPS, Thrips tabaci POPULATION ON GARLIC CROP AND THEIR EFFECT ON RESULTANT YIELD.

An experiment was carried out under field conditions at Ziton village in Beni-Sueif Governorate during two successive seasons, 2011-2012 and 2012-2013 to choose the suitable time of insecticide applications and their effect on T. tabaci infestation on garlic plants and resultant yield. The four tested treatments by applying two recommended insecticides at different times of plant growth were Carbosulfan (Marshal 20% EC with recommended rate 200 cm^3/ fed.) and Spinetoram (Radiant 12% SC with recommended rate 120 cm^3 Results and their statistical analysis showed clearly that all treatments significantly decreased the population density of T. tabaci and increased the garlic yield comparing with control treatment. The applying of Carbosulfan and Spinetoram at 15 day intervals (12 times of applications) throughout the whole growing season of garlic plant till one month before harvesting (T1) lead to reduce the population density of T. tabaci infesting garlic plants and gave the highest yield in the two studied seasons, as an average head weight of 12463.50 kg / feddan. Although, garlic plants which treated by Carbosulfan and Spinetoram after one month of sowing date from Nov., 1/ fed) compared with the untreated garlic plants. st at 30 old days till Dec., 15th However the application of T3 (Spraying of Carbosulfan and Spinetoram from Jan., 1 (4 times of applications) (T2) infested by higher number of T. tabaci,then gave the considerable head yield (9313.50 kg / feddan). st of at 90 old days till Feb., 15th) and T4 (spraying of Carbosulfan and Spinetoram from March 1st at 150 old days till April, 15 th