Abstract
Two experiments were carried out at College of Agriculture and and Forestry , Mosul Universty in 2003 growing season to determine the doses , frequency , duration time of application at different stage of Johnson grass growth on the efficiency of paraquate for control S . halepense . Data was subjected to the conventional analysis of Randomized Complete Block Design ( RCBD) as a factorial experiment . Results indicated that all concentrations used had effect on plant growth but there is no significant effect between different doses on growth of S . halepense rhizomes . Plant that received 0.15 , 0.30 , 0.60 L a.i / ha of paraquate at every week were more effect which reduce plant length up to 82.1 , 88.3 , 88.3 % respectively , while there was no rhizomes emerge when it spray every 3 or 4 weeks interval . However , the reduction of shoot length and dry weight were up to 44.3 and 47.5 % respectively with two times sprayed especially at flowering stage if it compared with the single application.
