NOTES: 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.
Growing on Plastic Mulch
Plasticulture is a common practice for okra since it is such a warm season crop. 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. Kill the weeds between the mulch prior to setting the okra plants on the plastic.
Stale Seedbed
See Stale Seedbed Technique for information on the use of these herbicides or flaming.
- glyphosate (Roundup Power Max): PHI 14d, REI 4h, Group 9.
- paraquat (Gramoxone SL 2.0*): restricted use. REI 12h or 24h, Group 22.
- pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0.
Preemergent Herbicides (before weeds germinate)
- sulfentrazone (Aquesta 4F): REI 12h, Group 14. Apply 2.25-12 oz/A per application, only 1 application per year. Rate based on soil texture, organic matter and soil pH. Apply banded or broadcast before transplanting.
- trifluralin (Treflan HFP): REI 12h, Group 3. Apply 1-2 pts/A per application, only 1 application per year. Apply and incorporate before or immediately after planting. Incorporate 2-3’’ into the soil of the final seedbed within 24 hours of application. If incorporating after planting, take care not to disturb the seed. Disc twice for satisfactory incorporation. Rate based on soil texture.
Pre- and Postemergent Herbicides
- mesotrione (Callisto): PHI 28d, REI 12h, Group 27. Apply 3-6 oz/A per application, only 1 application per year. Can be applied as a row middle OR a hooded post-direct treatment (but not both) for weed control in okra. Injury risk is greatest on sand, sandy loam or loamy sand soils. If applying in row middles, apply 6 oz/A as a banded application prior to weed emergence. Leave one foot of untreated area over the okra row or 6" to each side of the planted row. Do not apply directly over the planted row. If applying as a directed spray, apply 3 oz/A to actively growing weeds using a hooded sprayer to minimize contact with okra foliage. Okra must be at least 3” tall.
- prometryn (Caparol 4L): PHI 14d, REI 12h or 48h, Group 5. Apply 1.5-3 pts/A per application, up to 2 applications allowedper year. Do not exceed 3 pts/A per year. Can be applied after planting, before crop emerges or as a directed spray when the okra plants are at the 7- to 9-leaf stage and before weeds are 2” tall.
Postemergent Herbicides (after weeds germinate)
- carfentrazone (Aim EC): PHI 0d, REI 12h, Group 14. Apply 0.5-2 oz/A per application, multiple applications allowed per year. Do not exceed 6.1 oz/A per year. Apply 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” tall and rosettes less than 3” across. Can also apply up to 2 oz/A as a preplant burndown no later than 7 days before planting by seed or immediately before transplanting.
- clethodim (Select Max): PHI 3d, REI 24h, Group 1. Apply 9-16 oz/A per application, up to 4 applications per year, a minimum of 14 days apart. Do not exceed 64 oz/A per year. Apply to actively growing grasses. Add 0.25% v:v nonionic surfactant (1 qt/100 gal of spray). Can also be applied as a spot-spray by mixing 0.33-0.66% (0.44-0.85 oz/gal) Select Max and 0.25% v:v nonionic surfactant (0.33 oz/gal). Spray to wet, but do not allow runoff of spray solution.
- glyphosate (Roundup Power Max): PHI 14d, REI 4h, Group 9. Apply 10 oz to 3.1 qts/A per application, multiple applications allowed per year. Do not exceed 5 qts/A per year. Rate based on target weed species. Can be applied during fallow intervals, prior to planting or transplanting, at planting, or before crop has emerged. Could cause injury when applied prior to transplanting or direct-seeding into plastic mulch. Remove residual product from plastic mulch with a 0.5” of water through irrigation or rainfall prior to planting.
- halosulfuron (Sandea): PHI 30d, REI 12h, Group 2. Apply 0.5-1.5 oz/A per application, up to 2 application allowed per year. Do not exceed 2 oz/A per year. Apply between rows of okra for control of broadleaf weeds. 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.
- paraquat (Gramoxone SL 2.0*): restricted use. REI 12h or 24h, Group 22. Apply 1.3-2.7 pts/A per application, up to 3 applications allowed per year, a minimum of 14 days apart. Do not exceed 5.3 pts/A per year. Only 1 application may be made before crop emergence, and 2 may be made after crop emergence. Use precision directed spray application equipment adjusted to prevent spray contact with crop plants. May be fatal if swallowed or inhaled. Applicators must complete an EPA-approved paraquat training listed on the following website https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training.... The training must be completed a minimum of every three years.
- pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0. Apply a 3-10% solution (3-10 gallons per 100 gallons of spray). Rate based on target weed species. Apply in 75-200 gal/A of spray or with a spot sprayer until foliage is wet but not to the point of runoff. Repeat applications as necessary. Can apply for vegetative burndown during site preparation, prior to crop emergence from soil, as a directed and shielded spray during crop growth taking care to avoid contact with foliage and green tissue of crops, or after harvest.
- sethoxydim (Poast): PHI 14d, REI 12h, Group 1. Apply 1.5 pt/A per application, multiple applications allowed per year. Do not exceed 5.5 pts/A per year. Apply to actively growing grasses. Use with crop oil concentrate (2 pt/A) or methylated seed oil (1.5 pt/A). Note that crop oil can cause injury under hot and humid conditions. Can also be applied as a spot-spray by mixing 1-1.5% (1.3-1.9 oz/gal) Poast and 1% v:v crop oil concentrate (1.3 oz/gal). Spray to wet, but do not allow runoff of spray solution.