Richard Snell
Barton County Extension Agent

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July 26, 2010
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Pasture weed control in summer


Early to mid-June is a popular time to spray pasture weeds and woody plants. I'm not always sure, though, that it's the smart thing to do.

Why do you spray weeds in pasture? Is it to kill plants that are poor forage or is it just force of habit and to make the pasture look nicer?

One of my favorite sources of information is Dr. Bruce Anderson, Hay and Forage specialist at the University of Nebraska. He has some similar thoughts to mine on this topic, as does Walt Fick, Range specialist in the K-State Agronomy Department.

Now I've got to admit, I often suggest using herbicides in pastures. But the more experience I get with grazing and pasture management, the less spraying I do. In fact, anytime a pasture is sprayed, it indicates that grazing has not been as effective as it could be or that the owner wants a quick fix.

Okay, what am I talking about? Well, several things really. First, for pasture to be profitable, it must have high management input but controlled dollar input. Spraying costs money. Money we might save with better management.

Second, livestock eat many plants we call weeds and when they do, these plants are no longer weeds. In fact, many weeds can be good feed if grazed while young and tender. Third, unpalatable weeds usually become established in pastures after grass is weakened by severe grazing, and they thrive when grazing management fails to encourage vigorous grass regrowth. And finally, unless pasture and livestock are managed to benefit both plants and animals, the weeds will be back despite your spraying.

Now, don't get me wrong! I'm not talking about noxious weeds such as bindweed or musk thistle. These weeds must be controlled by law and thus you do need to spray those. But annual weed species change with weather patterns, grazing pressure and other factors. Thus, I'm not a huge fan of spraying those.

The major problem with spraying weeds is that you can't pay for it with increased beef production. Many studies have shown this. For the landowner in Barton County, average native pasture rent runs about $14/acre. Some may go for as much as $21 but some as little as $7 depending on the consistency of the water source, the quality of the grass, weed and brush density, how good the fences are and whether any care may be given by the landowner. In most cases the herbicide cost will run from $3-$15 per acre. Then tack on $3-$5 per acre for application costs.

By the time the landowner pays the taxes and interest costs on borrowed money or figures the opportunity costs on investment dollars, there isn't much left for profit. Weeds have to virtually get to the point where there is nothing for the cattle to eat and thus leaving the pasture worthless before treatment becomes economical.

Margins are tight for the cattle producers as well so they really can't afford to pay for spraying either. In the latest Bluestem Pasture Report, pasture rent for the season on cow-calf pairs averaged $130. You might come closer to pay for herbicide costs by grazing stocker or yearling cattle, where you can measure gains easier.

Over-grazing and poor grazing distribution are two of the main reasons why we have pasture weed problems.

So why spray pastures? If you graze properly but you wish to speedup the process of replacing uneaten weeds with vigorous grass, that's a very good reason. Otherwise, spraying may be simply cosmetic and a waste of money.




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The Fence Post Updated Aug 14, 2012 04:43PM Published Jul 26, 2010 12:55PM Copyright 2010 The Fence Post. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.