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.
See section Soil Fumigation Outdoors in the Disease Management section. Proper use of Vapam can provide weed control and will be more economical if multiple plantings are used.
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.
- pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0.
Preemergent Herbicides (before weeds germinate)
- dimethenamid (Outlook): PHI 21d, REI 12h, Group 15. Apply 7-21 oz/A per application, only 1 application per year. Apply as a broadcast application when the radish has reached the 2-leaf stage but before the 4-leaf stage. Temporary leaf injury may occur.
- trifluralin (Treflan HFP): REI 12h, Group 3. Apply 1-1.5 pt/A per application, only 1 application per year. Apply and incorporate into the soil before planting. Rate based on soil texture and percent organic matter.
Postemergent Herbicides (after weeds germinate)
- carfentrazone (Aim EC): PHI 0d, REI 12h, Group 14. Apply 0.5-2 oz/A per application. Do not exceed 6.1 oz/A per season. Can be applied with hooded sprayers to control emerged weeds. 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.
- clethodim (Select Max): PHI 15d, REI 24h, Group 1. Apply 9-16 oz/A per application, up to 2 applications allowed per year, a minimum of 14 days apart. Do not exceed 32 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.
- pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0. Apply a 3-10% solution (3-10 gallons per 100 gallons of spray). Apply in 75-200 gal/A of spray. Can use preplant, before crop emergence, or as a directed and shielded spray during crop growth. Avoid contact with foliage or crop damage may occur. Can also be used as a harvest aid and dessicant to remove leaves before harvest. Spray to wet, but do not allow runoff of spray solution.
- sethoxydim (Poast): PHI 14d, REI 12h, Group 1. Apply up to 2.5 pt/A per application, only 1 application 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.