Weed Identification – Part 2

What is this weed?

Poa Annua is an annual bluegrass which is a cool-season grass weed that starts germinating in late summer or fall as soil temperatures fall below 70°F. It continues to germinate throughout winter, allowing several flushes of germination at any one site throughout the season. Poa Annua grows 6 to 8 inches high when left unmowed. It has light green flattened stems that are bent at the base and often rooted at the lower stem joint. Leaf blades are often crinkled part way down and vary from 1 to 3 inches long with typicalPoaboat-shaped leaf tips. The inflorescence (flowering structure) has branched seed clusters (panicles) that are 1 to 4 inches long. Seed clusters, also called seed heads, can form as soon as plants are six weeks old; although this can occur from early fall through early summer, most seed heads are formed in spring.

It has a fairly weak and shallow root system and needs frequent rainfall or irrigation to survive. It grows well in moist areas in partial shade to full sun and tolerates compacted soil conditions.

Poa Annua is typically a problem in the lawn because it dies back in hot weather, which can make unsightly brown spots in the lawn during the height of summer. It also thrives during cool weather, when most lawn grasses are dormant, which means that it invades the lawn at these susceptible times.

Here in Oklahoma it is now dying off due to the rise in temperature. The best way to control Poa Annua is through Pre-Emergent, however AgriLawn does spot treat existing Poa Annua for control. The seeds can remain dormant for years before sprouting. The best way to control Poa Annua is to be consistent with weed control. AgriLawn offers a variety of weed control programs. Contact us today at 405-680-0077 to discuss the best option for your needs.