Many lawn care operators in warmer regions contend with Poa annua on an annual basis, according to Dean Mosdell, Ph.D., technical services manager for Syngenta.

He notes that when conditions are favorable, it also proliferates as an annual to perennial biotype in cool-season turf where germination occurs, and it establishes itself as a competitive weed in lawns that are overwatered, shaded or lacking density.

Ben Pease, turfgrass agronomist at The Andersons, agrees.

“It’ll typically come in in areas where the turf isn’t doing too well, where it’s been thinned out by a disease or it’s encountered some sort of destruction,” Pease says. “If the turf isn’t fed properly, the weed that prefers low fertility will overtake other turf. To keep a balanced fertility program, you want some fast-release nitrogen as well as some slow-release nitrogen to keep the turf fed, rather than a large flush of growth.”

Below are a few additional items to keep in mind when combatting Poa:

• Poa is lighter green than most of the desired lawn species. It has a wide blade and is a prolific producer of seed heads. The seed heads are initially green before turning to white. — Pease
• Poa is a clump grass that will slowly spread. Somewhere halfway down the leaf, the leaf will look crinkled as if someone were to fold a piece of paper into an accordion style. — Pease
• Leaves can be rolled in the bud and have boat-shaped tips. — Mosdell
• Properly selecting the lawn species for a region and site is paramount. For example, Bermudagrass may be suitable in the South, but not if the lawn is mostly shaded. — Mosdell
• Maintain proper mowing heights for lawns, fertilize turf based on recommendations from your state’s extension service and monitor irrigation practices. Lastly, make sure to deeply water, at least beyond the upper 2 inches, and water infrequently to avoid favoring the shallow-rooted Poa annua. — Mosdell
• Introducing new cultivars helps fill in blank areas and outcompete the Poa before the Poa has a chance to take over those weakened spots. — Pease