See section on Soil Fumigation Outdoors. Proper use of Vapam can provide control of most weed species.
Stale Seedbed
The following herbicides are nonselective and are used to control weeds that 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.
- pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0.
Preemergent Herbicides (before weeds germinate)
HRAC Group 3:
pendimethalin (Prowl H2O): Up to 3 pt/A (PHI 60d) or 3.1 to 8.2 pt/A (200d); REI 24h. Do not exceed 8.2 pts/A per year. Apply to the soil surface at least 1 day before transplanting.
HRAC Group 14:
flumioxazin (Chateau SW): 4 fl oz/A. REI 12h; 1 application per year. Apply no later than 2 days before transplanting.
Pre- and Postemergent Herbicides
HRAC Group 14:
oxyfluorfen (Goal 2 XL): 4 to 6 pt/A; PHI 5d, REI 24h. Do not exceed 6 pt/A per year. Apply a minimum of 60 days after transplanting. Contact with crop will cause damage.
Postemergent Herbicides (after weeds germinate)
HRAC Group 0:
- pelargonic acid (Scythe): 3% to 10% solution; PHI 1d, REI 12h. Apply before planting, or as a directed and shielded spray during crop growth. Contact with crop will cause damage.
HRAC Group 1:
clethodim (Select Max): 9 to 16 fl oz/A; PHI 5d, REI 24h. Do not exceed 64 fl oz/A per year. Apply to actively growing grasses.
sethoxydim (Poast): 0.5 to 2.5 pt/A; PHI 7d, REI 12h. Do not exceed 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 2:
- halosulfuron (Sandea): 1 to 2 oz/A; PHI 5d, REI 12h. Do not exceed 2 oz/A per year. Avoid contact with plastic mulch. Contact with crop will cause damage.
HRAC Group 9:
- glyphosate (Roundup Power Max): 10 fl oz to 3.1 qt/A; PHI 5d (spot treatment), 14d (all other uses), REI 4h. Do not exceed 5 qt/A per year. Apply during fallow intervals, prior to planting, at planting, before crop has emerged, or to row middles with a hooded or shielded sprayer or wiper applicator. Spray contact can cause crop death.
HRAC Group 14:
- carfentrazone-ethyl (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 no later than 1 day before transplanting or as a hooded application between beds.
HRAC Group 22:
- paraquat (Gramoxone SL 3.0*): 1.7 to 2.7 pt/A; PHI 1d, REI 48h. Do not exceed 5.3 pt/A per year. Apply between rows as a directed shielded spray after crop establishment. 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.