EFFECT OF SULFONYLUREA HERBICIDES ON EGYPTIAN BROOMRAPE (OROBANCHE AEGYPTIACA) IN TOMATO (LYCOPERSICON-ESCULENTUM) UNDER GREENHOUSE CONDITIONS

A time course of Egyptian broomrape development on tomato roots grown in pots in the greenhouse revealed an increase in the number of parasi tic attachments from 2.6 at 4 weeks after planting (WAP) to 139 when r ated 2 wk later. Rimsulfuron sprayed on tomato foliage as single and s plit applications (12.5 g ai/ha) 3, 4, 5, 6, and 7 WAP did not decreas e Egyptian broomrape damage to tomato plants, as expressed by reduced tomato plant height and fresh weight, and the total number of parasiti c attachments on the roots was not significantly different compared to the nontreated control. A single foliar application of rimsulfuron (2 5 g ai/ha) to tomato at 10 days after planting (DAP) and split applica tions at 10 and 20 and 10, 20, and 30 DAP significantly reduced the nu mber of Egyptian broomrape inflorescences to 2.2, 0.2, and 0, respecti vely, 9 WAP compared with 19.6 inflorescences in the nontreated contro l. Application of the herbicide under the same conditions to tomato pl ants in pots covered with activated charcoal did not significantly inf luence the number of Egyptian broomrape inflorescences. Chlorsulfuron and triasulfuron applied directly to the soil at rates greater than or equal to 3.75 g ai/ha completely controlled Egyptian broomrape. Primi sulfuron and chlorimuron, each at 22.5 g ai/ha, reduced the number of inflorescences to 0.6 and 0.4, respectively. Chlorimuron did not signi ficantly reduce the total number of parasitic attachments on the roots , but primisulfuron at the same concentration significantly increased the total number of parasitic attachments on the root system to 50 as compared to 23 in the nontreated control. Tribenuron had no effect on the parasitism process, as reflected in the number of inflorescences a nd parasitic attachments on the roots.