Weed Control

Stale Seedbed

The following herbicides are nonselective and are used to control weeds which are present in a field prior to planting or before the crop emerges, which is especially useful for the Stale Seedbed Technique (see the Weed Management section for more information).

• glyphosate (Roundup Power Max): PHI 14d, REI 4h, Group 9.
• paraquat (Gramoxone SL 2.0*): PHI 30d, REI 48h, Group 22. *Restricted use: Applicators must complete an EPA-approved paraquat training every 3 years: https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training-certified-applicators.
• pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0.

Preemergent Herbicides (before weeds germinate)

HRAC Group 0:

• napropamide (Devrinol 2-XT): 2 to 4 qt/A. REI 24h. 1 application per year. Apply before transplanting or before or after direct seeding. May be applied before laying plastic mulch or between plasticulture beds.  

HRAC Group 3:

• pendimethalin (Prowl H2O): 1 to 3 pt/A. PHI 21d, REI 24h. Apply as a broadcast surface application under plastic mulch, before transplanting crops, in a band to previously untreated row middles between beds, or as a directed spray after transplanting. Contact with crop will cause damage.

• trifluralin (Treflan HFP): 1 to 2 pt/A. REI 12h. 1 application per year. Apply and incorporate before transplanting, or apply after transplanting as a directed spray between rows and incorporate. A second incorporation pass in the opposite direction may be required.

HRAC Group 14:

• sulfentrazone (Aquesta 4F): 2.25 to 12 fl oz/A. REI 12h. 1 application per year. Apply banded or broadcast before transplanting.

HRAC Group 15:

• s-metolachlor (Dual Magnum): 1 to 2 pt/A. PHI 30d for applications 1.33 pt/A or less, 90d for applications greater than 1.33 pt/A, REI 24h. Apply before transplanting, or as a directed spray after transplanting, or between beds (including plasticulture). Can be applied to soil prior to laying plastic mulch. Damage may occur in some conditions—see label.

Pre- and Postemergent Herbicides

HRAC Group 2:

• halosulfuron (Sandea): 0.5 to 1 oz/A. PHI 30d, REI 12h. Do not exceed 2 oz/A per year. Apply to soil no less than 7 days before transplanting tomatoes onto bare ground, or just prior to laying black plastic. Apply over-the-top, post-directed, or with shielded sprayer to established and actively growing tomatoes, no less than 14 days after planting. Apply between beds, including plasticulture beds, as a directed spray or with wiper applicator. Split applications will help with nutsedge control—see label.

• rimsulfuron (Matrix SG): 1 to 2 oz/A. PHI 45d, REI 4h. Do not exceed 4 oz/A per year. Apply broadcast or banded after transplanting. Under stressful growing conditions, temporary chlorosis may occur but should not affect yield. 

HRAC Group 5:

• metribuzin (Metribuzin 75): 0.3 to 1.3 lb/A. PHI 7d, REI 12h. Do not exceed 1.3 lb/A per year—see label for additional restrictions. Apply as a broadcast application to the soil surface immediately before transplanting, or over the top of established and actively growing transplants. Do not apply within 24 hours of treatment with other pesticides or within 3 days after periods of cool, wet, or cloudy weather.

Postemergent Herbicides (after weeds germinate)

HRAC Group 0:

• pelargonic acid (Scythe): 3 to 10% solution. PHI 1d, REI 12h. Apply preplant, or as a directed and shielded spray during crop growth. May be used in high tunnels. Contact with crop will cause damage.

HRAC Group 1:

• clethodim (Select Max): 9 to 32 fl oz/A. PHI 20d, REI 24h. Do not exceed 64 fl oz/A per year. Apply to actively growing grasses. 

• sethoxydim (Poast): 0.5 to 1.5 pt/A. PHI 20d, REI 12h. Do not exceed 4.5 pt/A per year. Apply to actively growing grasses. BASF has stopped production and will discontinue the registration at the end of 2027.

HRAC Group 9:

• glyphosate (Roundup Power Max): 10 fl oz to 3.1 qt/A. PHI 14d, REI 4h. Do not exceed 5 qt/A per year. Apply during fallow intervals and up to 3 days prior to planting, at planting, before crop has emerged, or to row middles with a wiper applicator.  Spray contact may cause crop death. Turn air circulation fans off when applying inside a greenhouse.

HRAC Group 14:

• carfentrazone (Aim EC): 0.5 to 2 fl oz/A. PHI 0d, REI 12h. Do not exceed 6.1 fl oz/A per year. Apply as a preplant burndown immediately before transplanting or to row middles of emerged crops with a hooded sprayer, including crops grown on plastic mulch. Contact with crop will cause damage.

HRAC Group 22:

• paraquat (Gramoxone SL 2.0*): 1.3 to 2.7 pt/A. PHI 30d, REI 48h. Up to 3 applications allowed before planting, 3 applications after planting, and 2 applications after final harvest as a desiccant. Do not exceed 8 pt/A per year. Can also be applied after the crop has emerged with a directed spray. May be fatal if swallowed or inhaled. *Restricted use: Applicators must complete an EPA-approved paraquat training every 3 years: https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training-certified-applicators.