Dry weather prompts more cheatgrass development
Cheatgrass first made its appearance in the U.S. as a packing material for dishes and other goods shipped from countries like Europe, southwestern Asia and northern Africa. Long before styrofoam packing peanuts were introduced, cheatgrass was overtaking overgrazed native grasses in the United States.
Also known as downy brome, cheatgrass is hard to control because it saps up early spring moisture before native grasses come out of dormancy. “It is one of the most widespread, problematic weeds in the western United States,” according to Brian Mealor, who is the director of the Sheridan Research and Extension Center with the University of Wyoming. “People have studied the plant since the 1940s, trying to determine the best way to manage it,” he said.
Although there are a few methods of control out there, good pasture management strategies seem to be key, Mealor said. “Cheatgrass is an annual plant. You have to get moisture at the right time to germinate the seed. If you don’t, there is the potential that you won’t have cheatgrass.”
Moisture in the fall tends to encourage germination of the plant, Mealor said. “It is a winter annual, so if it germinates in the fall, it will go through the winter as a seedling. If the temperature rises above freezing, the plant can actually put down roots and grow. That gives it the advantage of taking moisture from our better grasses before they reach their active growth period.”
If it is grazed early, Mealor said cheatgrass can actually be nutritious for livestock to graze. “For livestock to use it and get any benefit from it, they have to graze it before it turns purple. Once it starts to make seedheads that are really sharp, livestock will start to avoid it. If it can be grazed while it’s green, and early in the season, it’s probably as nutritious as a lot of our other grasses. The problem is, if it’s a dry year, that green period may only last a week or two. Once the plant starts to turn purple, it loses all its nutritional value,” he said.
The best time to graze cheatgrass is dependent on the amount of precipitation received that year and the elevation. For example, Mealor said in areas like Laramie, Wyo., producers can graze cheatgrass into May, but in lower elevation areas of the state, producers may see cheatgrass turning purple by late April. Once the plant starts to mature and develops sharp seedheads, it goes from being a desirable forage for livestock to kindling for wildfires.
If the plants can’t be controlled through management, Mealor said producers may need to check into chemical control. Some producers may be able to get by with one application, but it is possible the plants may regrow two to four years later because viable seeds can still be present in the soil. Producers only have a small window in the fall to apply the chemicals and see results. Mealor said its best to apply the herbicide before the plants start to germinate and establish themselves. “It will work even better if you can apply it just ahead of when you are expecting some moisture. Here, we apply the chemical in the second half of September or the first half of October,” he said.
If producers plan to invest money in controlling cheatgrass, Mealor cautions them to inventory their native grass population, so if they can get some control of the cheatgrass, the native plants can recover. A stand of cheatgrass can suppress the growth of native grasses in the spring, especially if it’s the only early moisture received. “If periodic moisture is received through the early part of the growing season and through the summer, it may not have as much of an effect on other grasses. In drier years, the cheatgrass will take that early moisture so it isn’t available for perennial grasses. It suppresses their growth,” he said.
Mealor cautions producers not to rely on plentiful moisture to keep cheatgrass at bay. “It is a cheap plant that doesn’t invest a lot in its leaf and stem structure, so it will break down easy and relatively quickly this winter. However, if you have dense patches of it now, don’t assume those will go away based on precipitation patterns. If is best to consider some chemical control this fall.” ❖
— Clark is a freelance livestock journalist from western Nebraska. She can be reached by email at firstname.lastname@example.org.
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