NOTE: For the herbicides listed below, one product trade name and formulation is provided for each active ingredient along with preharvest interval (PHI), restricted entry interval (REI), resistance management group number, and example of rates and special instructions. In many cases, there are other products available with the same active ingredient. However, not all products with the same active ingredient are registered for use in a crop. Always check the product label to be sure that the crop is listed before using.
Suggestions for weed management in okra include use of the Stale Seedbed Technique and use of plasticulture. Plasticulture is preferred for okra since it is such a warm season crop.
See Stale Seedbed Technique (page 107). In place of herbicides, flaming can also be used.
carfentrazone (Aim EC): REI 12h, Group 14. Apply up to 2 oz/A per application, and do not exceed a total of 6.1 oz/ per season.
glyphosate (Roundup Power Max): REI 12h, Group 9.
paraquat (Gramoxone SL 2.0*): restricted use. REI 12h, Group 22. Use 2 – 4 pts/A.
pelargonic acid (Scythe): PHI 1d, REI 12h, Group 17. Use a 3 -10% solution (3 to 10 gallons per 100 gallons).
Stale seed beds can be used between plastic mulch (be careful with flaming as it melts the plastic). Some hand weeding may be needed in the planting holes as okra grows slowly at first after transplanting. Apply the plastic at least 2 to 3 weeks prior to planting and kill the weeds between the mulch prior to setting the okra plants on the plastic.
Herbicides Used Preemergence to Weeds
trifluralin (Treflan HFP): REI 12h, Group 3. Apply 1 to 2 pts/A as a soil-incorporated treatment prior to planting. Select rate based on soil texture and crop, see label for details. Must be incorporated into the top 2 to 3 inches of the final seedbed within 24 hours of application. Disc twice after spraying for satisfactory incorporation. See label for info on incorporation recommendations based on different equipment and single pass incorporation.
Herbicides Used Pre- and Postemergence to Weeds
mesotrione (Callisto): PHI 28d, REI 12h, Group 27. Callisto can be applied as a row middle OR a hooded post-direct treatment (but not both) for weed control in okra. Do not make more than one application of Callisto per okra crop. Injury risk is greatest on coarse-textured soils (sand, sandy loam or loamy sand). Do not apply Callisto as a broadcast preemergence or broadcast postemergence application to okra or severe injury will occur. Do not apply Callisto directly over the planted okra row or severe crop injury may occur. Controls many annual broadleaf weeds, including common lambsquarter and triazine resistant biotypes. Temporary injury, appearing as whitening of the foliage after emergence, may occur. Varieties may differ in sensitivity to mesotrione.
Preemergence row-middle application: Apply Callisto at a rate of 6.0 oz/A as a banded application to the row middles prior to weed emergence. Leave one foot of untreated area over the okra row or 6” to each side of the planted row. For banded applications, the application must be made to account for band width, i.e. to deliver 6.0 fl oz per treated acre.
Postemergence hooded application: Apply Callisto at a rate of 3.0 fl oz/A as a postemergence directed application using a hooded sprayer for control or partial control of the weeds listed in Table 28, page 109. Okra must be at least 3” tall at the time of this application. It is recommended that a nonionic surfactant (NIS) type adjuvant at a rate of 0.25% v/v be added to the spray solution. For postemergence hooded applications, the spray equipment must be set up to minimize the amount of Callisto that contacts the okra foliage or crop injury will occur. For best postemergence results, Callisto must be applied to actively growing weeds.
prometryn (Caparol 4L): PHI 14d, REI 12h, Group 5. Primarily controls annual broadleaf weeds. Annual grasses may only be suppressed. Can be used preemergence and/or post-directed to okra. Make a single preemergence broadcast application of Caparol 4L after planting before crop emergence at the rate of 3.0 pt/A. For two applications make the first preemergence after planting, before crop emergence at the rate of 1.5 pt/A and the second post-directed when okra plants are at 7-9 leaf stage at the rate of 1.5 pt/A. Apply post-directed before weeds are 2 inches tall. Do not exceed one preemergence and one post-directed application per crop cycle. Do not exceed 3 pt/A of Caparol 4L per crop cycle.
Herbicides Used Postemergence to Weeds
carfentrazone (Aim EC): REI 12h, Group 14. For use between rows after crop establishment. Aim is a burndown herbicide and will injure any foliage it comes into contact with. Apply Aim to row middles of emerged crops with hooded sprayers to control emerged weeds, including crops grown on mulch or plastic. Prevent any spray from contacting the crop, or injury will occur. For best results, make application to actively growing weeds up to 4 inches tall and rosettes less than 3 inches across. Good coverage is essential for good control. Apply up to 2 oz/A per application, and do not exceed a total of 6.1 oz/ per season.
halosulfuron (Sandea): PHI 30d, REI 12h, Group 2. Apply between rows of okra for control of broadleaf weeds. Avoid crop contact. If plastic mulch is used, keep the herbicide off the plastic. DO NOT allow Sandea to contact the planted crop or crop injury will occur. See label for additional precautions. Excellent on velvetleaf, smartweed, ragweed, pigweed. Good on yellow nutsedge and morning glory. Use 0.5 to 1.5 oz/A per application. Do not apply more than 2 times per season and do not exceed 2 oz/A per year. See label for list of weeds and other precautions. Weed control may be reduced without the use of a surfactant.
paraquat (Gramoxone SL 2.0*): REI 12h, Group 22. For use between rows after crop establishment. Apply up to 2 pt/A as a directed and shielded spray to emerged weeds between rows when weeds are succulent and weed growth is less than 6”. Maximum 3 applications per year, not to exceed a total of 8 pt/A per season. Allow 14 days between applications. Use precision directed spray application equipment adjusted to prevent spray contact with crop plants. Crop contact by the spray will cause severe injury or death. Do not exceed 30 psi nozzle pressure or spray under conditions which may cause excessive drift.
pelargonic acid (Scythe): PHI 1d, REI 12h, Group 17. Use a DIRECTED/SHIELDED SPRAY; contact with crop will cause injury. Use a 3 -10% solution (3 to 10 gallons per 100 gallons). Use a 3 to 5% solution for annual weeds, a 5 to 7% solution for biennial and perennial weeds, and 7 to 10% solution for maximum burndown. Delivery rate for boom applications should be 75 to 200 gals of spray solution per acre; complete coverage of weed foliage is essential. For hand-held equipment, spray to completely wet all weed foliage but not to the point of runoff. Repeat applications as necessary. Tank mixes are allowed with this product. See label for complete details.