Agronomy and Horticulture Department


Date of this Version



Insect Science, Plant Disease, & Weed Science, University of Nebraska Cooperative Extension, Institute of Agriculture and Natural Resources 89(12) (June 13, 1989)


Copyright 1989 University of Nebraska


In This Issue:

  • Postemergence Weed Control in Grain Sorghum
  • Small Grain Harvest Aid
  • Pasture and Range Weed Control
  • Lawn Weed Control

Postemergence Weed Control in Grain Sorghum

Crop growth stage restrictions are an important consideration when choosing a postemergence herbicide for use in sorghum. This year's uneven stands complicate the situation further. Our advice is to gauge treatments based on how the majority of the field develops. Earlier applications may allow lower rates, better coverage, and more effective weed control. Do not cultivate for 5 days prior to or after a herbicide application.

Small Grain Harvest Aid

Thin stands coupled with the recent rains may lead to excessive weed growth in ripening small grains. Broadleaf weeds, especially, can cause serious harvesting problems. 2,4-D ester at 1 quart per acre (4 lbs. per gallon material) will knock down and dry up most broadleaf weeds. No tall brands of 2, 4-D are labeled for this use. Applications made after the hard dough stage of the grain will not affect grain yield. By waiting until the green color is gone from the nodes -(joints), stem brittleness and breakage can be avoided. It usually takes 7-10 days for the 2,4-D to knock down and dry up the weeds.

Pasture and Range Weed Control

Normally, the later part of June is the best time to treat broom snakeweed, vervain, goldenrod, sagebrush, snow-on-the-mountain, and western ragweed. There is a tendency to treat on the late side rather than too early. A good guideline for treating most perennials is to mow or apply the herbicide when the weeds are in the early flower bud stage. Biennial thistles are an exception and should be treated in the rosette stage.

Lawn Weed Control

Summer months are not the time to apply herbicides for perennial broadleaf weed control in turf. Dry, hot weather reduces the effectiveness of most postemergence herbicides and control suffers. wait until late September to early October to control perennial broadleaf weed problems. In addition to lack of control, high temperatures and wind speed increase the chances of drift and volatility problems which will cause injury to sensitive plants. This is especially true for materials that contain dicamba (Banvel), but 2,4-D and MCPP (mecoprop) can also cause drift injury.