Weed Control

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.  

Many growers choose to grow basil on plastic mulch. Basil usually grows quickly and shades the planting hole in plasticulture, out-competing weed growth. Apply the plastic at least 2 to 3 weeks prior to planting and kill the weeds between the mulch prior to setting the basil plants on the plastic. On bare ground culture, keep cultivations shallow to protect crop roots. Do not move soil into the crop row as basil plants may be more susceptible to diseases when soil is mounded against the stems of the crop.

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)

clomazone (Command 3ME)PHI 50d, REI 12h, Group 13. Apply 10.7 oz/A per application, only 1 application per year. Apply before seeding or transplanting, or after seeding but prior to crop emergence. Place seed, or roots of the transplants, below the chemical barrier when planting.Apply in a minimum of 10 gal/A of spray. Use the lower rate on sandy soils and the higher rate on silt and clay soils.  

napropamide (Devrinol 2-XT)REI 24h, Group 0. Apply 2-4 qt/A per application, only 1 application per year. Can only be applied to transplants before planting. Use the lower rate on sandy soils and the higher rate on silt and clay soils. Incorporate 2-4” into the soil with shallow cultivation or water through irrigation or rainfall within 24 hours of application. If using plastic mulch irrigate with sufficient water to wet to a depth of 2-4” if soil is dry, incorporate into the soil, and then lay mulch on the same day as application.

Postemergent Herbicides (after weeds germinate)

carfentrazone (Aim EC)REI 12h, Group 14. Apply up to 2 oz/A per application, multiple applications allowed per year. Do not exceed 6.1 oz/A per year. Can be applied 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.

clethodim (Select Max)PHI 14d, REI 24h, Group 1. Apply 9-16 oz/A per application, up to 4 applications allowed 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 per 100 gal of spray).  Can also be used as a spot-spray by mixing 1/3% to 2/3% (0.44 to 0.85 oz per gallon) Select Max and 0.25% v:v nonionic surfactant (0.33 oz per gallon).  Spray to wet, but do not allow runoff of spray solution. Has not been tested on all varieties, crop tolerance should be verified before treating the entire field. If no crop response is evident seven days after treatment, Select Max Herbicide may be used on the entire field at the rate tested.

glyphosate (Roundup PowerMax)PHI 7d, 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 24h, 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, or as a directed and shielded spray during crop growth. Avoid contact with foliage or crop damage may occur. Spray to wet, but do not allow runoff of spray solution.