The Egyptian broomrape (Orobanche aegyptiaca Pers.) is an obligate holoparasitic weed that causes severe damage to many important vegetable and field crops. In this investigation, three herbicides; chlorsulfuron, triasulfuron and imazaquin were tested to evaluate their efficiency in controlling the tomato broomrape. The herbicides significantly reduced the broomrape parasitizing tomato plants growing in pots, irrigated open field and under greenhouse conditions as foliar spray at the

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... ons (0.5 -10 µg·ml −1 ) without visible injury effect on the plants. In the pot experiments, triasulfuron increased the dead spikes from 77% to 84%; chlorsulfuron from 51% to 84% and imazaquin from 52% to 84% at the concentrations (0.5 -5 µg·ml −1 ) compared with the control. In the irrigated open field experiment, the herbicides were less efficient in controlling the broomrape. The dead spikes increased from 10.5% to 29.1% at the concentrations (1 -5 µg·ml −1 ) compared with the control. In the greenhouse experiment, the herbicides were more effective than open field and the dead spikes were increased from 30 to 68% at the concentrations 5 and 10 µg·ml −1 . In conclusion, the foliar application of herbicides were able to increase the broomrape dead spikes attached to the tomato plants at the concentrations (3 -5 µg·ml −1 ) without visible negative effect on tomato plants. The Effect of Herbicides on the Egyptian Broomrape (Orobanche aegyptiaca) in Tomato Fields 347 The Effect of Herbicides on the Egyptian Broomrape (Orobanche aegyptiaca) in Tomato Fields