Effectiveness of Glyphosate in Broomrape (Orobanchespp.) Control in Four Crops

We studied the effectiveness of glyphosate [N-(phosphono-methyl)glycine] for the control ofOrobanchespp. in the field when applied to the crop foliage prior to the emergence of the parasite. The bestOrobanchecontrol in October-sown carrots (Daucus carotaL.) parasitized byOrobanche crenataForsk. andO. aegyptiacaPers. and in December-sown broad bean (Vicia fabaL.) and peas (Pisum sativumL.) parasitized byO. crenatawas obtained by spraying twice, 2 weeks apart, in late January and in February, respectively. Carrot root yield remained unaffected by glyphosate at rates up to 200 g/ha. In heavily infested fields, carrots were irreversibly damaged by earlyOrobancheparasitism. The highest yields of pods of broad beans occurred after two or three applications of 150 g/ha glyphosate. Peas were seriously damaged by 150 g/ha. Two or three sprays of 50 g/ha glyphosate resulted in the highest green-kernel yield of pea where the soil was not heavily infested. Glyphosate effectively reducedO. cernuaLoeffl. emergence in non-irrigated tomatoes (Lycopersicum esculentumMill.), but was very phytotoxic to the crop. Glyphosate was highly effective in controllingOrobanchespp.; however, marginal selectivity may be sufficient in some crops and not in glyphosate-susceptible ones.