Drip-applied metam potassium and herbicides as methyl bromide alternatives for Cyperus control in tomato

Field trials were conducted to determine the efficacy of pre-emergence herbicides and metam potassium (metam-K) on density of a mixed stand of Cyperus esculentus and Cyperus rotundus in tomato (Solanum lycopersicum L.). Treatments consisted of a combination of doses and application methods of the herbicides napropamide + S-metolachlor (2.3 + 1.5 kg a.i./ha) and EPTC (4.0 kg a.i./ha), as well as the presence or not of drip-applied metam-K (400 kg a.i./ha). A non-treated control and a grower standard (methyl bromide + chloropicrin) were added. Results indicated that drip-applied EPTC was injurious to tomato, while the drip-applied combination of napropamide + S-metolachlor was ineffective against the weed. The best combinations were obtained with bed top applications of either napropamide + S-metolachlor or EPTC followed by metam-K, which provided similar levels of Cyperus control and tomato yields to methyl bromide + chloropicrin treated plots.