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?).
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: https://extension.colostate.edu/docs/pubs/natres/06310.pdf
Best of luck and happy fall everyone!!
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