Fall Management of Cool-Season Invaders in Pastures
When cheatgrass, bromes, and other cool-season plants invade native warm-season grass pastures and rangeland, they shift good grazing away from summer.
Cool-season grasses take over summer pastures relatively easily because they develop rapidly during fall and spring when native grass provides little competition. Then they use moisture and nutrients during spring before warm-season plants have a chance to use them.
Heavy grazing this fall after warm-season plants go dormant after a hard freeze as well as grazing very early next spring will weaken and reduce competition from these winter annual weeds. This can limit further invasion and slowly improve summer production. A prescribed spring burn also can do wonders for a warm-season pasture if you have enough fuel to carry a fire and can conduct the burn safely and legally.
An even faster approach is to apply a glyphosate herbicide after a couple hard freezes in late fall. Hard freezes turn warm-season plants dormant while weedy cool-season grasses remain green. For best results apply glyphosate when daytime temperatures are above 60ºF and nighttime temperatures stay above 40ºF. This will kill or weaken the green and susceptible cool-season weedy grasses, but not affect dormant warm-season plants.
By reducing competition, warm-season plants will grow more vigorously next year and provide better summer pasture.