This troublesome weed has been causing nightmares for homeowners, golf courses, sod producers and sport field managers alike. Even so, this annual invasive species of Eurasian bluegrass isn’t the only reason for pre-emergent treatments in warm-season lawns.
It forms the large dead patches of yellow mat in your summertime lawn. This annual grassy weed will aggressively compete with other more desirable plants for both lawn and garden space.
Grass for more northern climates are considered “cool season” species, while grass better suited to Georgia’s southern turf are “warm season” species.
Warm season grasses are slower to germinate and to establish themselves during the initial growing season when compared to grassy weed species. This means Poa annua, crabgrass, goose grass and barnyard grass are problem weeds as the seeds will germinate in the spring, grow throughout the summer, produce and distribute seeds, and die off at the onset of cold weather.
Weed control begins with proper lawn care and management. You want a healthy, dense turf. A thick turf in and of itself will lessen the invasion of grassy weeds, as root space is not available for those ready to grow weed seeds.
Pre-emergent lawn treatments are most effective in controlling annual grass weeds like crabgrass, goose grass and Poa annua (European walkgrass). It is applied to the soil before weed seed germination and will be absorbed by the newly germinated young roots and shoots as they grow.
Annual grass weeds will invade lawns, be unpleasant to look at by interrupting the uniformed appearance of your lawn, and will be unpleasant for barefoot walking. Grassy weeds are fierce competitors and will steal important soil nutrients and water, and tend to be prolific seeders. And these grassy weeds will be among the first plants to grow in a cleared or recently-disturbed soil area like your garden beds.
Poa annua will form large mats during the cooler months from fall to spring, but its high production of seeds and yellow die-off will look awful during the heat of summer. As an annual, Poa annua will complete its life cycle in one growing season. Texas A&M University found that one plant will produce more than 350 viable seeds in its lifetime, and these seeds can remain dormant for years. Michigan State University believes no other grassy weed adapts to a variety of conditions like Poa annua.
When in doubt, contact your lawn care specialist for testing and effective pre-emergent application to keep your lawn beautiful and barefoot-friendly all season long.