For Release October 1, 2006

All Those Flowers in the Pastures, Aren't Necessarily Weeds

AGRI-VIEWS

by Chuck Otte, Geary County Extension Agent

There is a perception, by many native pasture owners and managers, that a native prairie is most productive when it is all grass. Any non grass plants, whether they be shrubs, trees, forbs or simply what we might call wildflowers are invasive, unwanted, will crowd out the grass and must be killed. So about this time of year I start to receive phone calls from these land managers wanting to know how to get rid of all those "weeds" in the pastures.

The conversations frequently go something like this. "I need to get rid of these weeds in my pasture." "What weeds?", I ask. "All those things that are blooming right now." is the usual response. "Why do you think you need to get rid of them?", I query. I know what's coming now; "Because there's no grass in the pasture, these weeds are crowding it all out."

The land manager has correctly identified a problem; there isn't very much grass left in the pasture. But the cause and effect has gotten a little scrambled. Few, if any, of the wildflowers that are blooming now, forbs if you will, have the ability to crowd out native grass. Woody perennials can crowd out and smother native grass. Invasive, noxious weeds like musk thistle and sericea lespedeza can crowd out native grass, but not pitcher sage, or liatris or annual broomweed or curlycup gumweed. If these plants, and many others, appear to be the dominant vegetation in your pasture, at this time of year, then they are there because the grasses weren't. And the grasses are not there because of, most likely, overgrazing.

No native grass manager likes to think that they've overgrazed a pasture. Yet the only way that native grass stands can lose vigor and productivity, is when more leaf area is removed, and ultimately plant carbohydrate reserves, than the plant can replace. This can happen very easily and very unintentionally. It can happen by failing to reduce stocking rate due to reduced production from drought. Or it may be not adjusting the stocking rate to compensate for larger (hungrier) cattle that are part of today's cattle industry. Even simply by overestimating the acres of grass in a pasture due to loss of grass acres by tree or shrub invasion.

In basic concept, more consuming animal units were placed in the pasture than there was forage that could safely be harvested. Instead of maintaining balance, the forage resources were mined and depleted. Once the grasses were depleted, the ecosystem was opened up where other plants could proliferate due to the lack of competition from the grasses.

Spraying the pastures at this time of year is going to be very ineffective. Many plants are going dormant, or they will be dying with the first frost anyway. Besides, spraying the forbs (weeds) is not dealing with the problem, it only addresses the symptom. More forbs or weeds will move in next spring, because of the lack of competitiveness of the grass stand.

Fixing the problem is a multiple year project. It will require that you evaluate your pasture to determine how many acres of usable forages you have. Then you will need to reduce the stocking rate for two or three years so that the grass plants can start to recover and regain their former competitive state. With more forage remaining at the end of the year, you can then conduct better prescribed burns to try to regain the proper balance of grasses and forbs that we need in a high producing native prairie. Then, once the prairie has regained it's previous balance and productivity, it will require you to continue to stock at the proper rate and be ready to reduce stocking rates when adverse growing conditions occur again.

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