Gage County
1115 West Scott St.
Beatrice NE 68310
Phone: (402) 223-1384
FAX: (402) 223-1370

News Column

Paul C Hay, Extension Educator

Lawn Weed Killers

This is Botany 101, English 101 and Chemistry 101 in laymen's terms for homeowner's lawn weed control. I promise to use words longer than four letters, but refrain from unpronouceable chemical names.

Botany 101 - If you have some idea how the weed grows and how the weed killer works it will help you get better control. As an example dandelions are a perennial weed (they live many years). Dandelions store energy in the fall in the root in order to be able to flower and produce seed quickly in the spring. Killing dandelions in October-November will mean a yellowless lawn in the spring. Henbit has recently moved from town to farmers fields and is giving us a spectacular purple display as we drive the countryside.

In lawns, grass is the best way to control henbit. If it is solid in the lawn that means your grass is very thin or non-existent. Either overseed the area and care for the new grass or if it is bad enough work up the area and seed new grass. Don't forget to think about why the grass was thin in the first place. If there is a problem it will likely reoccur and until that is solved no amount of seed or weed killer will cure the henbit invasion. Crabgrass germinates when soil temperatures top 60 degrees. This is usually May 1 in our area. Pre-emergent crabgrass control materials should be applied just ahead of this time in last two weeks of April. Application of lawn fertilizer and pre-emergent crabgrass killers in March or early April can be quite a problem. Early fertilization gives lots of top growth, roots are developing slowly, summer heat starts to stress the grass and the pre-emergent material fades early giving an opportunity for crabgrass to break the system.

English 101 - Take the time to read the label on all fertilizer and weed control materials. When it says control on the label that means 85% or higher kill rate. When it says suppression it means the weeds get sick but do not die. Be sure to read about potential adverse effects which leads us to Chemistry 101.

A very common and quite safe weed killer or broadleaf weeds, like dandelions, is 2,4-D. There are several formulations and other chemicals are often mixed with 2,4-D. A common mistrake often made by farmers and acreage owners is to use 2,4-D LV ester instead of 2,4_D amine on their lawns. This can result in damages to trees, flowers and shrubs which is largely avoided with 2,4-D amine. Homeowners should check the chemical ingredient section of the label and make sure that among all this gibberish they see 2,4-D amine. Another ingredient is some lawn wee killers is dicamba (Banvel). Trimec is one example of a material like this. Make sure in this situation to read the label about application timing, rate, and warnings about potential damage to nearby flowers, tres, and shrubs. Products like this should be applied no more than twice per year, carefully to avoid contact with above ground foliage, and out of the root zone of sensitive plants and perennial flower beds. Avoid using weed killers with dicamba from June 1 until September 1 when there is increased risk from the product.

View other Gage County News Columns & News Letters: http://gage.unl.edu/news/news.htm

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