Cheatgrass. This is one invader weed that is hated by homeowners and ranchers alike. Its relentless advance across much of North America since it was first found near Denver around 1861, is nothing short of astounding. It is found everywhere in North America except the extreme southeastern states.
So why is cheatgrass so disliked by all that come in contact with it? First off it is a prolific seed producer with over 300 seeds produced per plant per year. And while it is an annual, it gets an early start with its seed germinating during the fall/winter period. It is thus able to gain a competitive advantage over other annuals whose seed germinates in the spring or perennials that lie dormant over the winter.
Cheatgrass produces an extensive lateral root system able to penetrate to depths of up to 28 inches. By doing so this grass can use up all available soil moisture, denying other plants life-saving water. Next, cheatgrass is more tolerant to overgrazing and fire. In fact, it was overgrazing of native prairies that led to the rapid establishment of cheatgrass in the west. And finally, in the summer when this grass is dry, it is extremely combustible resulting in frequent large-scale burns. These fires often kill off native plants, leaving only a cheatgrass monoculture.
But before continuing this conversation, let us detail a few more facts about this grass. Its Latin name is Bromus tectorum and while most of us call it cheatgrass or cheat, its accepted common name is downy brome. Some also call it drooping brome because of its drooping habit. Cheatgrass probably originated in southwest Asia but was first sent to the Mediterranean area before coming to America in packing material.
Cheatgrass seedlings look nothing like their mature parents. They are very flat, small and inconspicuous until the warmth of spring gives them a growth spurt. While mature plants can reach up to 30 inches tall, in lower rainfall areas such as ours we rarely see plants bigger than about 12 inches, and often much smaller. This grass grows in a bunch with leaf blades covered with soft hairs. Seed heads droop, are one sided, 2-6 inches long with slender spikelets, 3/8-3/4 inch long. Each spikelet contains awns which are those troublesome "stickers" that get trapped in our socks, tennis shoes and our dog's ears and paws.
Seeds of cheatgrass are dispersed by wind, rodents, dogs and other animals, and of course by us. They also are spread through contaminated hay, straw or machinery. They can lie dormant for up to 11 years. If there is insufficient moisture for fall/winter germination then seeds can germinate in response to spring rains.
So how are we going to control this major invader? We can resort to hand pulling of established plants. But if a larger area is involved, mowing is an option. Make sure you catch, bag and remove all seed-producing plants. Large areas can also be grazed or burned. Use a post emergence chemical control approach of existing grass with Assure II®, Fusilade®, Poast®, or Roundup® herbicides, before seed is produced. A better approach is to use a pre-emerge herbicide in late August/early September, such as Maverick® or Treflan® and Preen®. As always, read and follow all label instructions.
If you missed the window of opportunity to prevent cheat grass seed germination this year then you can look forward to using a mechanical or chemical control approach of your cheatgrass next year. One more chore on a long list I bet!
Jim Leser retired to Cedaredge in 2007 after a career with Texas A&M University Extension in entomology. He is a member of the Cedaredge Tree Board and a Colorado Master Gardener.