Grass Weed Control

Soil-Applied Grass Herbicides

dimethenamid (Frontier 6.0): 16 to 32 ounces/A (50 dh, REI 12h, Group 15). May be applied preplant surface, preplant incorporated, preemergence, or postemergence (up to 8” tall corn). A split application may be used. Will not control emerged weeds. Check with seed supplier for potential varietal susceptibility to injury.

pendimethalin (Prowl H20): 2 to 4 pt/A (REI 24h, Group 3). Apply preemergence only after seeding. Do not incorporate into the soil. A broadleaf herbicide such as atrazine or simazine should also be used to control broadleaf weeds. If this herbicide is moved into the seed zone, there is potential for crop injury. Some basic suggestions for minimizing the potential for crop injury are to plant in a firm seedbed, plant corn seed at least 1.5” deep, plant into moist rather than dry soil, do not mix Prowl with liquid fertilizers, and avoid sandy soils. If the soil is dry, consider irrigating instead of waiting for rainfall prior to application. If heavy rains follow an application to dry soil, Prowl can move to the seed zone and cause crop injury. Specific weeds for which this herbicide should be considered include triazine-resistant lambsquarters, and velvetleaf. Growers may consider a lower rate of Prowl in addition to using a broadleaf herbicide and another grass herbicide such as Dual Magnum (metolachlor), Lasso (alachlor), Frontier (dimethenamid), Sutan+ (butylate) or Eradicane (EPTC+safener).

Preplant Incorporated Herbicides (Thiocarbamate Family): These herbicides must be broadcast over the soil surface and incorporated prior to seeding.

butylate (Sutan+ 6.7E): 3 3/4 pt/A (REI 12h, Group 8). Apply before planting and immediately work into soil with a disc to a depth of 2” to 3” for annual grasses and 4 to 6” for nutsedge. Weak on many broadleaf weeds. May be tank mixed with atrazine or cyanazine to improve broadleaf weed activity.

EPTC + safener (Eradicane 6E): 2 7/10 to 4 qt/A (REI 12h, Group 8). Provides similar grass weed control to butylate but offers better control of pigweed and velvetleaf. Must be incorporated immediately to a depth of 2” to 3”. May be tank mixed with atrazine or cyanazine to improve broadleaf weed activity.

Soil Surface Applied Herbicides (Acetanilide Family)

alachlor (Lasso 4EC): 2 to 3 qt/A (REI 12h, Group 15). Apply to the soil surface after seeding. Generally weak on lambsquarters and ragweed. May also be applied after crop emergence to weed-free soil before crop is 5” tall. May cause some temporary crop burn if applied after corn emergence.

metolachlor (Dual Magnum): 1/2 to 2 pt/A (REI 12h, Group 15). Apply to the soil surface after seeding. Poor control of lambsquarters. May also be applied after crop emerges to weed-free soil before crop is 5” tall.

Postemergence Applied Grass Herbicides

pelargonic acid (Scythe 4.2): 3% to 10% (REI 24h, Group 27). Use a 3-5% solution for annual weeds (4-6 oz/gal water), a 5-7% solution for biennial and perennial weeds (6-9 oz/gal water), and 7-10% solution for maximum burndown (9-13 oz/gal water). Delivery rate for boom applications should be 75 to 200 gal spray solution/A; 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. These include tank mixes with glyphosate (Roundup), sulfosate (Touchdown), and residual herbicides. See label for complete details.