Farm Talk

April 8, 2014

Controlling weeds and brush in pastures


Parsons, KS — I’ve always wondered about the saying “The grass is always greener on the other side of the fence”. That may be true, but what about the weeds and brush on that side of the fence, are they greener too? Spring has arrived, and along with it, the time has come to start thinking about weed and brush control in our range and pasture land.

The first step towards weed and brush control is simply understanding what species you have and want to control. Two possible pasture weed candidates, musk thistle and sericea lespedeza, are classified as noxious weeds in Kansas. The Kansas Noxious Weed Law first enacted in 1937 requires landowners to control and eradicate weeds on lands they own or manage. Each state decides which plants are classified as noxious which can cause some confusion. Sericea, for example, is not listed as noxious in Arkansas, Missouri, or Oklahoma.

Musk thistles have deeply lobed, hairless leaves that are dark green with a silver gray leaf margin. Musk thistles can be difficult to observe in the spring because they are in the rosette stage, a prone growing condition that they remain in until bolting occurs. Bolting occurs when the plant extends its flowering stalk upward. Once the flower stalk is extended, the plan is readily observed, especially when the pink to dark purple flower develops. Chemical control of musk thistle occurs best before bolting and works best when the temperature is between 70 and 90 degrees Fahrenheit. A wide variety of herbicides are available to control musk thistle. In many counties, the noxious weed department has chemicals available to help control those noxious weeds.

Sericea lespedeza is a perennial legume that is actually considered a crop in some of the United States and labelled a noxious weed by Kansas. One of the reasons it is listed is that it can be difficult to control. Also, once established, sericea reduces, or even eliminates, the surrounding vegetation. The plant itself has an erect stem with somewhat woody stems. The leaves are actually made of three leaflets very close to the main stem. Complicating control is the longevity of the seed, which can remain for reportedly 20 years, or even more. There are some chemical control options for Sericea lespedeza. The old standby for sericea control is an application of the active ingredient Triclopyr (i.e. Remedy) during the actively growing vegetative stages in June or even flowering in late July and August followed up by a spraying of the active ingredient Metsulfuron (i.e. Escort). There are additional chemical control options available as well and, since it is a noxious in Kansas, contact your county weed department.

Noxious weeds are not the only issue in pastures in our area. Brush can be a problem, and, if left alone can take over pastures. Locust trees, for example, can cause some issues. If you have a private pesticide applicators license, the active ingredient Picloram (i.e. Tordon 22K) can be applied foliarly. If you do not have a private pesticide license, a general use active ingredient called Aminopyralid (i.e. Milestone) can be applied. Either of these should be applied when the locust tree leaves are fully expanded in late spring.

Eastern red cedar can be another issue in our pastures. Ideally, mechanically cutting cedars below the lowest branch is recommended. If chemical control is preferred, the active ingredient Picloram (i.e. Tordon 22K) can be used. Burning can control cedars as well. Just as a reminder, there is no need to treat the stump of a cut cedar since it will not resprout. Other trees, including hedge, elm, and mulberry, do require a chemical stump treatment if mechanically removed.

As in all spray situations, make sure you read and follow the label instructions. If you have questions or would like more information, please call me at the office 620-724-8233, or email me at, or visit the Wildcat Extension District website at www.