Weed Control in Production of Okra in Trinidad

Weed control is frequently a severe limiting factor in okra [Abelmoschus esculentus (L.) Moench] production in the Caribbean. The objective of this field investigation was to further evaluate the effectiveness of selected herbicide treatments to control weeds in okra and to determine their effects on the yield and quality of okra under rainfed conditions. The research was conducted for 3 consecutive years on River Estate loam, a fluventic eutropept, in Trinidad. Preplant herbicide treatments of benefin (N-butyl-N-ethyl-ά, ά, ά-trifluoro-2, 6-dinitro-p-toluidine), butralin [4-(1, 1-dimethylethyl)-N-(1-methylpropyl)-2, 6-dinitrobenzenamine], and trifluralin (ά, ά, ά-trifluoro-2, 6-dinitro-N, N-dipropyl-p-toluidine) and preemergence herbicide treatments of benefin, butralin, DCPA (dimethyl tetrachloroterephthalate) + diphenamid (N, N-dimethyl-2, 2-diphenyl-acetamide), DCPA, diphenamid, nitrofen (2,4-dichlorophenyl-p-nitrophenyl ether), and prometryn [2, 4-bis (isopropylamino)-6-(methylthio)-s-triazine] were applied to ‘Dwarf Long Green Pod’ okra. All herbicide treatments controlled weeds during the first 28 days after treatment. At 42 days after treatment good weed control was obtained with prometryn, trifluralin, preplant benefin, and diphenamid; and acceptable weed control was obtained with preemergence benefin and DCPA. Preplant benefin and trifluralin, and premergence benefin, prometryn, and diphenamid gave fruit yields (i.e. weight and numbers) that were equivalent to those of the handweeded check and superior to those of the other treatments. None of the herbicide treatments significantly affected the grading quality, total carbohydrate, protein, fat, or moisture content of the okra fruit. Slight initial injury to okra plants was caused by prometryn, diphenamid, and DCPA + diphenamid. The DCPA alone caused some leaf distortion which later disappeared. With the exception of nitrofen, which reduced stands, no other symptoms of injury were observed. Results of this study indicate that preplant or preemergence herbicide treatments can be used effectively in okra production.