Weed Control

NOTE:  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. 

Stale Seedbed

See Stale Seedbed Technique (page 107).

glyphosate (Roundup Power Max): REI 12h, Group 9.

paraquat (Gramoxone SL 2.0*): restricted use. REI 12h, Group 22. Use 2 – 4 pts/A. Include a nonionic surfactant at 0.25% v/v, or crop oil concentrate/methylated seed oil at 1.0% v/v (1 gal/100 gal) of the finished spray volume for maximum efficacy. 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-certified-applicators. The training must be completed a minimum of every three years.

pelargonic acid (Scythe): PHI 1d, REI 12h, Group 17. Use a 3 -10% solution (3 to 10 gallons per 100 gallons).

Herbicides Used Preemergence to Weeds

clomazone (Command 3ME): REI 12h, Group 13.  Apply 21.3 fl oz/A to the soil surface after seeding but prior to crop emergence. Place seed, or roots of the transplants, below the chemical barrier when planting. Will control annual grasses and many broadleaf weeds including common lambsquarters, velvetleaf, and jimsonweed. Some temporary crop injury (partial whitening of leaf or stem tissue) may be visible after crop emergence. Complete recovery will occur from minor early injury without affecting yield or earliness. See label for replanting restrictions.

linuron (Lorox DF): REI 24h, Group 5. Make a single application of up to 2 lbs/A after planting but prior to crop emergence. Use lower rates on coarse soils and higher rates on heavier soils.

s-metolachlor (Dual Magnum): REI 12h, Group 15.  English peas and dry peas. Apply either preplant incorporated or to the soil surface just after seeding. See label for specific rates on different soil types and organic matter content (1 to 2 pt/A). NOTE: If soil is cold and wet during pea germination/emergence, use of Dual Magnum can delay maturity and reduce yield. 

pendimethalin (Prowl H2O): REI 24h, Group 3. Apply 2 to 3 pt/A preplant and incorporate into the soil 2" to 3". Do not apply after seeding.  Rainfall or irrigation is required for activation.

trifluralin (Treflan HFP): REI 12h, Group 3. English peas. Incorporate 1 to 1.5 pt/A before planting. Select rate based on soil texture; see label for details.  Must be incorporated into the top 2 to 3 inches of the final seedbed within 24 hours of application.  Disc twice after spraying for satisfactory incorporation. See label for info on incorporation recommendations based on different equipment and single pass incorporation. Especially effective for annual grass.

Herbicides Used Pre- and Postemergence to Weeds

imazethapyr (Pursuit): PHI 30d, REI 4h, Group 2. English peas and dry peas.  Apply up to 3 oz/A as a preplant incorporated (with 1 week of planting) or as a preemergence up to 3 days after planting. 

Can also be used early Postemergence:  Apply to dry peas and English pea when peas are 3” tall but before 5 nodes and before flowering. Nonionic surfactant must be added to the spray solution for post emergence use.

Herbicides Used Postemergence to Weeds

bentazon (Basagran): PHI 10d, REI 48h, Group 6.  Used postemergence on actively growing weeds.  Rate varies based on weed species targeted (1 to 2 pt/A). Peas are tolerant to after 3 pairs of leaves (or 4 nodes) are present.  Pea injury such as yellowing, bronzing, speckling or burning of leaves may occur under certain conditions.  Temporary injury is generally outgrown without delay of podset, maturity or reducing yields. An effective treatment in an emergency situation to control certain broadleaf weeds and fairly effective against yellow nutsedge when 4" to 6" tall.  Do not apply when peas are in bloom or under stress from root rot.  Do not add oil for use on peas.

carfentrazone (Aim EC): REI 12h, Group 14.  Aim is a burndown herbicide and will injure any foliage it comes into contact with. Apply Aim 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 inches tall and rosettes less than 3 inches across. Good coverage is essential for good control.  Apply up to 2 oz/A per application, and do not exceed a total of 6.1 oz/ per season. 

clethodim (Select Max): PHI 21d, 24hr REI, Group 1.  Will control grass weeds only. Apply to actively growing grasses.  See label for rate selection.  A single application of 9 to 16 oz/A is permitted.  Apply before bloom. Add 0.25% v:v nonionic surfactant (1 qt per 100 gal of spray).  Can also be used as a spot-spray by mixing 1/3-2/3% (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.

pelargonic acid (Scythe):  PHI 1d, REI 12h, Group 17. Use a 3 -10% solution (3 to 10 gallons per 100 gallons). Use a 3 to 5% solution for annual weeds, a 5 to 7% solution for biennial and perennial weeds, and 7 to 10% solution for maximum burndown. Delivery rate for boom applications should be 75 to 200 gals of spray solution per acre; complete coverage of weed foliage is essential. Use a DIRECTED/ SHIELDED SPRAY; contact with crop will cause injury. For hand-held equipment, spray to completely wet all weed foliage but not to the point of runoff. Repeat applications as necessary. Tank mixes are allowed with this product. See label for complete details.

quizalofop (Assure II): PHI 60d dry peas, PHI 30d succulent peas, REI 12h, Group 1. Apply to actively growing grasses. Rate based on target weed species, see label for grass growth stage and rate selection.  Multiple applications permitted.  Allow at least 7 days between applications.  Do not exceed 14 oz/A per season.  Apply with either crop oil concentrate or non-ionic surfactant. Do not apply when crop or weeds are under drought stress.

sethoxydim (Poast): PHI 30d dry peas, PHI 15d succulent peas, REI 12h, Group 1.  Controls grass weeds only.  Apply to actively growing grasses (see product label for susceptible stage).  Maximum 2.5 pt/A per application, minimum 14-days between applications.  Do not exceed 4 pt/A per year. Use with crop oil concentrate (2.0 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 used as a spot-spray by mixing 1-1.5% (1.3 to 1.9 oz per gallon) Poast and 1% v:v crop oil concentrate (1.3 oz per gallon).  Spray to wet, but do not allow runoff of spray solution.