Validation of integrated pest management components for onion thrips in the Gezira area

This study was carried out at the Gezira Research Station (GRS) in Wad Medani and the University of Gezira Research Farm during the two successive seasons 2004/05 and 2005/06. The study was conducted to investigate the effects of three integrated pest management (I PM) components i. e. effect of irrigation, varietal resistance or tolerance and time of planting, for Thrips tabaci control on onion.The irrigation intervals, 7, 10 and 14 days, with flooded and normal irrigation in each interval, sowing at the recommended sowing date (middle of October), 15 days earlier and 15 days later were studied. Also, twenty three onion cultivars were screened for susceptibility to the onion thrips. The results indicated that, in both seasons, the numbers or thrips were very low at shorter irrigation interval (7 days) than at the other irrigation intervals. Flooded irrigation reduced the numbers or thrips. However, in both seasons 7 days interval of normal irrigation resulted in the highest yield (9.7 ton/fed and 10.9 ton/fed., respectively».Saggai cultivar was found to be the most tolerant cultivar among the all tested onion cultivars. It had the lowest numbers of thrips and highest yields. 9.7-16.5 tons/fed were obtained with Saggi Improved while the yields of Dongla yellow were 5.0-5.97 tons/fed. In both seasons, until the end of February the thrips numbers were higher in the first planting date than the other two planting dates. But in March the second planting date had more number of thrips than the other two planting dates. However, the earliest (beginning of October) planting date gave the highest yield in both seasons than the other two planting dates (11.6 ton/fed and 10.7 ton/fed, respectively). The yields obtained by the recomended sowing date were 8.1 and 7.2 tons/fed, in the two seasons respectively. While the latest sowing date (the end of October) resulted in the lowest yields 5.6 and 5.3 tons/fed. In conclusion the study suggests early planting date (beginning of October), 7 days normal irrigation and planting Saggai Improved cultivar for thrips management in onion