Now is an excellent time to make choices about managing weeds in pastures. Before applying herbicides for chemical control you first need to answer the question: “Why do I have weeds in my pasture”? If a management issue such as overstocking, spot grazing, low grass vigor or something else is causing the increase in weed numbers, then weeds are symptoms, not the real root of the problem. In this case, unless the underlying cause is addressed, you will continually have weeds on an annual basis, regardless of the chemical controls used.
On the other hand, there may be instances when grazing management alone cannot address weed issues. In these situations chemical control coupled with good grazing management can lead to a more long term solution.
Annual broadleaves are easiest and most economically controlled when they are about 2 inches tall. That usually will be somewhere around the late April or early May in our area. Perennials are best controlled when they are flowering or have completed flowering and actively growing, usually sometime in June depending on the weed. Of course weed growth and the weather don’t always abide by the calendar, so for best results always follow the rates and weed sizes listed on the label.
There are several different chemical options available. The best option will depend on price, effectiveness, and the weed type and size you are going after. A few of the chemical options are:
2,4-D works well on small annuals and at a higher rate satisfactorily on perennials. A rate of 3/4 lb. of active ingredient per acre will give good control on small annuals. A rate of 1 to 1 1/4 lbs will be needed for larger annuals or perennial plants.
For a broader spectrum of weed control and in some cases residual control, 2,4-D in combination with aminopyralid, dicamba or picloram maybe an option. Be sure to read the label for the proper mixing procedures and a list of those weeds controlled.
Metsulfuron is also another option, which provides residual control. Metsulfuron can also suppress fescue production and seedheads. There are several herbicides in which metsulfuron is the primary ingredient. An excellent K - State publication with specific recommendations for different weeds and forage types is available at: https://www.bookstore.ksre.ksu.edu/pubs/SRP1126.pdf or do an internet search for SRP 1126 2016 Chemical Weed Control.