Abstract
The efficacy of the University Boom Sprayer was tested for mortality rate of bollworms on cotton variety CM-496- PB planted at Post-graduate Aqricultural Research Station (PARS) experimental fields, University of Agriculture, Faisalabad. Both the booms (over to top conventional and upward spraying nozzles) washed the cotton leaves thoroughly and helped to kill bollworms lying in buds, squares, flowers, bolls and on leaves. The boom height and drop pipe angle (45° backward w.r.t. boom axis) were adjusted so as the drop nozzles hung between the rows in the middle of the upper half dense canopy prevent the crop and machine breakage. At the time of first spray, the only bollworm seen was spotted, while at second spray Spotted as well as American bollworms were seen. At first spray, boll worm mortality was evaluated at three intervals after spraying (24-hr, 48-hr, and 72-hr) while at second spray mortality rate measurements were made one day and one week after spraying. The mortality rate of spotted bollworms was found significantly affected by sprayer velocity, spraying pressure and spraying angle of drop nozzles. Greatest bollworm mortality was achieved 72-hr after spraying in case of first spray and one week after in case of second spray at 4.0 kmlh field speed, 400 kPa pressure, and 30 ° upward angle of drop nozzles w.r.t. horizontal. Key words: Bollworm, boom sprayer, cotton, nozzle, drop pipe
