OROBANCHE AEGYPTIACA CONTROL IN TOMATO WITH SULFONYLUREA HERBICIDES

Orobanche spp. are root holoparasitic that cause severe damage to vegetable and field crops worldwide. O. aegyptiaca is common throughout Israel and parasitizes a wide range of crops, including processing tomatoes. Efficacy of O. aegyptiaca control and selectivity of 4 tomato varieties to sulfosulfuron (Monitor, Monsanto, 75% WG), rimsulfuron (Titus, DuPont, 25% WG), and ethoxysulfuron (Sunrice, Avetis, 60% WDG) was studied under greenhouse and field conditions. Post application (POST) applied sulfosulfuron, rimsulfuron, and ethoxysulfuron at all tested rates did not injure Brigade, H-4077, and H-5811 tomato varieties. In H-LRT variety, minor developmental delay was observed when sulfosulfuron and ethoxysulfuron were applied POST at 150 and 200 g a.i. ha^-1, respectively, but plants recovered upon maturity. Pre planting incorporated (PPI) treatments, excluding rimsulfuron, were more phytotoxic than POST application. All the POST and PPI applied herbicide treatments resulted in effective O. aegyptiaca control. However, no O. aegyptiaca control was achieved at POST herbicide treatments when pots were topped with charcoal, suggesting that the herbicides were absorbed by the charcoal and could not penetrate into the soil. Field study conducted in naturally Orobanche-infested commercial field, confirmed the results obtained under greenhouse conditions. Rimsulfuron at 100, 150 and 200 g a.i. ha^-1, and sulfosulfuron at 50 and 100 g a.i. ha^-1 followed by 300 m³ ha^-1 sprinkler irrigation did not cause any damage to tomatoes and effectively controlled the broomrape. To prevent further Orobanche emergence, 3 g a.i. ha^-1 of chlorsulfuron (Glean, DuPont, 75% WG), injected directly into the drip irrigation system at 28, 42, and 56 DAP is required.