Thursday, January 08, 2009

Noel Mues, Extension Educator
University of Nebraska-Lincoln Extension

Homeowners frequently ask questions about lawn weed control during late summer. We think we have our turf weed problems under control – then suddenly in August they start showing up more than ever.

The most troublesome weeds in turf are the ones that make their appearance in late summer. Broadleaf weeds include field bindweed, ground ivy, violets, morning glory, puncture vine, and one of the most difficult to keep ahead of – prostrate spurge.

Grassy weeds can even be more of a problem to deal with. They include crabgrass, field sandbur and windmill grass – to name a few.

Many of the broadleaf weeds can best be controlled with fall treatments of 2,4-D, Banvel (dicamba) and MCPP herbicide combinations. Excellent herbicides are available which contain these combinations, such as Trimec and Turflon, which are effective on the tough weeds. Apply these anytime in October or Early November before a hard freeze.

Prostrate spurge and grassy weeds are a different story. Some control can be obtained with pre-emergence herbicides applied during the spring. Applications during mid to late April will control crabgrass, while another application during June will help control prostrate spurge and field sandbur.

In established lawns, young crabgrass and field sandburs can be treated, post-emergence, with arsenicals such as MSMA and DSMA, which are available at garden stores. Trimec Plus contains MSMA, along with other herbicide ingredients – 2,4-D, MCPP and Banvel – which will control a variety of broadleaf and grassy weeds. Many of these herbicides will damage warm season plants such as buffalograss. Be sure to always read and follow the label.

Remember the most beautiful lawns are the ones that have been cared for under a complete Integrated Pest Management (IPM) program. This includes proper weed, insect and disease treatments along with proper watering, fertilizer treatments and mowing. A thick, lush lawn will have very little room for weeds to invade.