The' present Investigation was carried out at the Agricultural Experiment and
Researd1 StatiOn, Faculty of Agriculture, Cairo University, Giza, Egypt, during the two
growing seasons of 1990/91 and 1991192 10 study the effect of the herbicide
glyphosate on the growth. and yield of faba bean. The effectiveness of giyphosate in
controlling Orobanche was also studied. In each season two experiments were curried
out, the first In Orobanche free field and the second in field naturally Infested with
Orobanohe. Glyphosate was applied as a post emergence foliar spray at doses of 0.0,
13.5, 27.0' and·4O.5 g,e.l.Jfed. Each dose was sprayed Ihrice at thr.ee weeks intervals
started at the beginning of host flowering. Application of glyphosate specially at the rate of 40.5 g.a.i./fed., to faba bean
grown In Orobanche free field negatively affected plant growth and yield. Using the
herbidde In field naturally Infested with Orobanche decreased number and dry weight
of broomrapes per faba bean plant. The rate of 40.5 g.a.i.Jfed of glyphosate
deaeased infection by about 97%. Consequently, the growth and yield oflhe host
treated plants increased, comparing with the untreated (infested) plants.