OROBANCHE AEGYPTIACA CONTROL IN TOMATO FIELDS WITH SULFONYLUREA HERBICIDES

Field experiments were conducted from 1994 to 1997 at two locations to study the effectiveness of chlorsulfuron and triasulfuron applied thr ough different irrigation methods (chemigation) for control of Orobanc he aegyptiaca Pers. in tomato (Lycopersicon esculentum Mill). Three sp lit applications of chlorsulfuron at 2.5 g a.i. ha(-1) and of triasulf uron at 7.5 g a.i. ha(-1), through conventional sprinkler irrigation s ystems, 10-14 days apart followed immediately by sprinkling with water , controlled O. aegyptiaca cl by about 90% and 80% and increased crop yield 25-47% and 30%, respectively, without any crop injury symptoms. Repented applications of the same herbicides at half rates resulted in slightly higher O. aegyptiaca control and crop yield than only one he rbicide application at double rate. Chemigation by the sprinkler syste ms (microsprinklers, 60 m(3) ha(-1)) slightly increased the herbicide efficiency as compared with the high volume spray (800 m(3) ha(-1)). O . aegyptiaca control from sulfonylureas applied by drip chemigation wa s poor, as this probably requires very accurate timing and the herbici de distribution in the soil was not uniform.