American Journal of Plant Sciences, 2012, 3, 346-352 doi:10.4236/ajps.2012.33041 Published Online March 2012 (http://www.SciRP.org/journal/ajps) The Effect of Herbicides on the Egyptian Broomrape (Orobanche aegyptiaca) in Tomato Fields Ibrahim Ghannam, Mohammad Al-Masri, Radwan Barakat * Faculty of Agriculture, Hebron University, Hebron, Palestine. Email: * radwanb@hebron.edu Received June 16 th , 2011; revised August 20 th , 2011; accepted November 3 rd , 2011 ABSTRACT 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 ima- zaquin were tested to evaluate their efficiency in controlling the tomato broomrape. The herbicides significantly re- duced the broomrape parasitizing tomato plants growing in pots, irrigated open field and under greenhouse conditions as foliar spray at the concentrations (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 herbi- cides were less efficient in controlling the broomrape. The dead spikes increased from 10.5% to 29.1% at the concentra- tions (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. Keywords: Orobanche aegyptiaca; Chlorsulfuron; Triasulfuron; Imazaquin; Broomrape and Tomato 1. Introduction The broomrape (Orobanche spp.) are obligate holopara- sitic weeds that cause severe damage to the most impor- tant vegetable and field crops in the Mediterranean re- gion and the Middle East [1]. Annual food crop losses due to broomrape infestation are estimated at about $1.3 to 2.6 billion. Egyptian broomrape (O. aegyptiaca) to- gether with branched broomrape (O. ramosa) infests about 2.6 million ha of solanaceous crops mainly in the Mediterranean area, North Africa, and Asia [2-4]. In Pal- estine, broomrape is listed as one of the most harmful weeds and poses a major constraint to crop production. The control of broomrapes is often difficult for various reasons and numerous control strategies have been tested over the years, with limited effectiveness. The control methods investigated have included changes in agricul- tural practices such as hand weeding, tillage, deep inver- sion, crop rotation, trap and catch crops, fertilization and soil solarization [1,5-8] as well as chemical and biologi- cal means [3,9-20]. The chemical control of broomrapes included soil fumigation and herbicide application. Soil fumigation with methyl bromide effectively controlled broomrape [18]. Several herbicides were used to control broomrape, but selectivity to the host plant remained the main obstacle. Chlorsulfuron applied at 5 g·a.i·h −1 gave 100% control of emerged broomrape shoots and under- ground attachments and completely prevent parasite de- velopment in tomato [21]. The herbicides rimsulfuron and sulfonylurea effectively controlled O. aegyptiaca in pots, but in drip-irrigated tomatoes fields, O. aegyptiaca control was poor [11]. The best results for Orobanche control in potato was obtained by applications of rimsul- furon at 12.5 g·a.i·h −1 followed by three sequential foliar applications of glyphosate at 100 g·a.i·h −1 [17]. Split ap- plication of low rates of imazamethapyr applied on toma- to foliage or chemigated via sprinkler irrigation achieved excellent O. aegyptiaca control throughout the growing season, but caused premature loss of flowers and early ripening of fruits [20]. During the last few decades, the herbicidal groups showed promising results in broomrape control; sulfony- lurea, imidazolinone, and other inhibitors of the enzyme acetolactate synthase (ALS) or acytohydroxy acid syn- thase (AHAS) are some examples. Members of these groups showed some degree of selectivity to broomrape host plants [3,10,14-16]. Chlorsulfuron, pronamide and * Corresponding author. Copyright © 2012 SciRes. AJPS