What is the weed situation like in your pasture?  If the fields I’ve been in are typical, then curly dock, pigweeds, ragweed, oxeye daisy, daisy fleabane, thistle and other weed species are flourishing.

Planning is the key to an effective herbicide program and the time to begin planning is now.  Weed control has to be one of the most frustrating tasks producers undertake.  However, choosing to simply do nothing only increases the weed density and population over time. With the multitude of chemicals on the market today and the many types of weeds currently growing in your fields, planning an effective herbicide program can be difficult.

Controlling weeds in a pasture is a two step process. The first of which is to encourage a vigorous, thick stand of grass or grass legume mix.  This would include maintaining optimum soil pH and fertility (soil testing on a regular basis) and grazing management.  Maintaining a high quality pasture of properly selected forages that your cattle will eat is one of the best ways to control weeds.

The second step would be to control existing weeds. This can be accomplished through mowing, using herbicides, and selective grazing practices, as needed.

Whichever method you chose, the key to good control is to do it early.  If you mow, do it before the weed blooms.  Pastures may need to be mowed two or more times during the season.  This may be an effective way of controlling annuals and some biennials but may be expensive and time consuming as compared to other options. 

If you choose to use herbicides, then remember the keys to good control.

The first step in the planning process is to identify problem weeds.  So, plan on taking a weed inventory.  When you walk your fields, take notes on weeds present and the severity of infestation.  Also, note weeds along the edge of the fields.  Sit down with other farm workers and discuss weeds that may have been a problem earlier in the season or in the past few years.  In the case of alfalfa, winter weeds may be very important.

The second step after the identification process would be to sit down and look at herbicide options.  Guides that will be helpful in selecting the best herbicides for your situation are the “Weed and Brush Control Guide for Forages, Pastures and Non-Cropland in Missouri” and the “Weed Control Guide for Missouri Field Crops”.  These are available for a nominal fee at County University Extension Centers.

In most cases, two or more combined herbicide programs will give adequate weed control.  This gives you, the producer, the opportunity to compare programs.  Comparisons based on costs per acre, effectiveness on a specific weed, and label restrictions and/or precautions used.

If you choose to use herbicides, then remember the keys to good control.

1. Spray when the plants are small.  Young plants are generally more susceptible to herbicides than larger (older) plants.

2. Weeds must be actively growing at the time the herbicide is applied.  If the plants are drought stressed or if it is too hot or too cold, you may not get a good kill.

3. There is a right and wrong time of the year to spray different weeds, and that is an essential part of a control program.

 Last, but not least, is to check on the availability of products.  In the current economic climate, most agricultural supply companies are exercising a tight inventory control.  They may not have a particular herbicide in stock.  But given enough time, they can usually order it.

Source: Terry Halleran , Agronomy Specialist