CO-Horts Blog

Thursday, October 10, 2019

Fall cheatgrass

Posted by: Kara Harders - Regional Small Acreage Management Specialist, Peaks and Plains

With the first cold snap of the year upon us, we Coloradans tend to have differing opinions of the coming weather and what it means. Some of us are singing “hip-hip-hooray!” for the cool weather, while others are lamenting the shortening days and end of shorts and flip flop season. However, most people who deal with weeds are probably feeling relief as the growing season comes to a dramatic halt.

As with most things in life, there is usually a grey area and an “it depends” answer for everything. The problem plants that seem to fill in this grey area of weed growth in the cooler months are the winter annuals. In my opinion, the biggest offender of the winter annual group is Cheatgrass/Downy brome/ Drooping brome/Bromus tectorum (it makes sense that something so evil has so many names, right?).

(Identifying Cheat grass without the seed head)

This annual noxious weed (which hails from the mythical land of Eurasia) depends entirely on its seed to reproduce year to year, but what makes it sort of unique is that it usually germinates in the fall, not the spring. This allows the plant to get started, lie in wait all winter establishing roots, and then bombard us first thing in the spring and “cheat” the other plants out of space and resources. Cheatgrass germination depends on environmental conditions, especially precipitation. Summer and fall rains cause rapid germination, but the plants need about 2” of rainfall to really get going. Another impressive factor to consider is the seeds can also germinate in the spring if they do not get enough moisture to get a fall start. Due to this flexibility, it is common to have plants of various ages in a Cheatgrass stand. Which is a real get-ya-downer.

So, what can we do?

If you have not seen any of the soft, delicate, lovely, green patches spring up yet, you can apply a pre-emergent to keep the seeds from germinating at all (woo-hoo). If you are seeing young Cheatgrasses you can spray them with an herbicide that effects grasses or simply pull them up. Really, any method of weed control (besides mowing) should be effective at this point. When killing Cheatgrass at this age always consider you are simply trying to kill the roots of this plant. Grazing at this stage is fine for animals but will probably leave viable roots for overwintering and spring growth, for this reason I would avoid relying only on grazing management to control the plant. The biggest benefit to treating Cheatgrass in the fall is they will not have seed heads yet, so you don’t need to worry about disposing of the seeds to prevent a problem next year!

If you would like more information on Cheatgrass in general check out this fact sheet:

Best of luck and happy fall everyone!!

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