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Life Out in the Country – Rain, Grass and Now Weeds 

by Wyoming Livestock Roundup

All of the spring rain has brought on a wonderful flush of prairie grass wildflowers and unfortunately, a lot of weeds. 

Currently blooming, the tall yellow spike which looks like snapdragons is dalmatian toadflax. This plant is considered a noxious weed and must be controlled. It is a perennial weed with a vigorous root system and massive amounts of seeds. 

Mature plants are very competitive, out-growing native grass and flowers. It’s not palatable by animals and contains iridoid glucoside compounds, which can be toxic to livestock.

Management approaches for weed control

There are several management approaches to control this or any weed. 

Timing is very important. The best times to spray toadflax or thistle is in the blooming stage. If this window is missed, then individuals should spray after the first frost in the fall. 

When it comes to understanding which herbicides are the best to use, individuals should contact their local county weed and pest office, not the local farm store. 

Mowing and fire are not an effective control method and can cause this weed to spread faster. 

Do not indiscriminately use pesticides or rodent poisons, they can get into well water or poison non-target animals. Use pesticides wisely, and read the label.

There are some biological controls where individuals can use live, natural enemies of the weed to reduce its population. This requires time and patience to work.  

One cannot mix chemical controls with biological controls – it has to be one or the other, but not both. 

A good reference book for this is entitled “Biological Control of Invasive Plants in the United States.” This book is an anthology of research on the topic.  

Benefits of letting the prairie grow wild

Native plants on the prairie form a vital habitat for many animals from bees and butterflies to mammals, but weeds prevent or alter this. Individuals should let their prairie go wild, control weeds and only mow around the house and out buildings.  

They should also plant grasses well adapted to the area and easy to grow from seed, such as western wheatgrass, thickspike wheatgrass, intermediate wheatgrass and many others. 

There is a very narrow window to plant grass – October to May 15. After that, one will need to wait, since it’s all about natural rain and snow. Once established, grasses take very little water, and they do not need to be mowed. 

Prairie grass stops growing around the middle to the end of May. What one will see on June 1 is all they will get for the rest of the growing season. A healthy prairie will out compete weeds.

The prairie is home to numerous birds like the meadowlark, lark bunting, horned lark and killdeer, who nest and raise their young on the ground, hidden in the prairie grass. 

Wyoming’s state bird, the western meadowlark, builds a domed nest of grass on the ground and has a diet of both insects and seeds. Nesting season is March to July. Be cautious with herbicides – 2, 4 D is toxic to birds.

Good management of prairie grass can help prevent soil erosion, reduce snow drifting, help recharge a well and reduce fire danger. Research shows un-mowed tall prairie grass is cooler, the soil holds more moisture, has less weeds and ground squirrels and deters prairie dogs.

Mow less, play more and enjoy the views and wildlife.   

Catherine Wissner is the University of Wyoming Laramie County Extension horticulturist. She can be reached at or 307-633-4480.

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