Redtop

Agrostis alba

Redtop is a perennial grassy weed that is also know as Agrostis gigantea or by its scientific name, Agrostis alba. This lawn weed is actually occasionally used as a filler in low-quality grass seed mixtures due to its propensity to thrive in poor soil qualities.

Identify

Rhizomes

Membranous

Rolled

Redtop can be identified as a blue-green-colored perennial grass—and sometimes lawn weed—with a creeping growth habit caused by rhizomes. Its ligule is rounded and very tall, and its collar is narrow, divided into two parts by a space. The sheaths of this grassy weed are smooth and not compressed, while the blades are flat, with prominent veins on upper surfaces and rough edges. Because it is versatile and can grow in a wide range of conditions and soil types, this grass-like weed is often used for erosion control and for stabilizing critical areas, including ditch and channel banks.

Life Cycle

This lawn weed grows well under a wide variety of soil and moisture conditions. It is able to thrive in very acidic soils, low fertility soils and also poorly drained soils. Redtop can be found throughout much of North America. These perennial grassy weeds can germinate and spread from seeds, but they also produce a root structure (tubers, bulbs or corms) that can birth new weeds from your lawn's surface (using stolons) or from underground (using rhizomes). Perennial grassy weeds live two or more years and have a deeper root structure that can give rise to new weeds—even if you no longer see the weeds in your lawn.

Control

Redtop is not an easy grassy weed to manage using cultural control methods—such as hand-pulling lawn weeds or proper watering and mowing—though frequent, close lawn mowing can discourage it from growing. However, that can damage the desired types of grass present in your lawn. For effective weed removal, professionally selected and applied weed control treatments are your best bet for eradication.