Influence of weeds and onion thrips, Thrips tabaci (Thysanoptera : Thripidae), on onion bulb yield in Jordan

Field experiments were conducted in two seasons to investigate the effects of weeds and onion thrips on onion bulb yield grown under irrigation. Treat ments were combinations of three levels of weed infestation and two onion t hrips infestation levels. Weed interference was found to severely reduce bu lb yield, whereas reductions from onion thrips infestations were of lower m agnitude. Hand weeding was more effective in weed control than a single oxy fluorfen application. No significant interactions were detected in this inv estigation between weeds and onion thrips infestations, which could be attr ibuted to the strong preference of onion thrips towards the crop over the w eeds. (C) 2000 Elsevier Science Ltd. All rights reserved.