Cooperative
Extension
Service


University of Illinois
at
Urbana-Champaign


No. 7/May 8, 1998

Options for Controlling Over-sized Vegetation in No-Till

A wet, cool spring has delayed corn planting across much of Illinois and has also given early weeds time to grow. Some no-till fields have an impressive display of healthy vegetation that will require management before planting corn or soybeans. Atrazine, Bladex, or Extrazine II have both foliar and soil activity but are limited in the size of weeds they control when used in notill burndowns. These products have fairly good activity on annual grasses 1.5 inches or less and on many broadleaf species in the 3-to-4-inch range. Options for controlling larger vegetation in no-till situations include 2,4-D or Banvel/Clarity for broadleaf species and Touchdown 5, Roundup Ultra, or Gramoxone Extra for grass and broadleaf weeds.

2,4-D ester may be applied at 1 pint per acre before planting corn or soybeans, but at least 7 days must elapse between application and soybean planting. Banvel or Clarity may be added to many preplant corn herbicides. Roundup Ultra or Touchdown 5 may be used at 1 to 2 pints per acre in many preemergence herbicide mixes. FieldMaster, a premix of Harness Xtra and Roundup Ultra, may be applied preplant or preemergence in corn at 3.5 to 5 quarts per acre.

Gramoxone Extra may be tank-mixed with several preplant or preemergence herbicide mixes for corn or soybeans at 1.5 to 3 pints per acre, depending upon weed size. The addition of atrazine, Bladex, or Extrazine II improves control of smartweeds, giant ragweed, and marestail with Gramoxone Extra in corn. Sencor or Lexone (also in Canopy) may be added to Gramoxone Extra for no-till soybeans.

Authority Broadleaf and Canopy XL (sulfentrazone + chlorimuron) have both foliar and soil-residual activity, primarily for broadleaf weed control, and may be applied preplant or preemergence in soybeans. Pursuit, Pursuit Plus, and Steel also have both foliar and soil-residual activity on many grass and broadleaf weed species.

Aaron Hager (hagera@idea.ag.uiuc.edu) and Marshal McGlamery (mmcglame@uiuc.edu), Department of Crop Sciences, (217)333-4424