How to Prevent Poa Annua (Annual Bluegrass)
Native to: Europe
Type of weed: winter grassy weed
GreenGrass treats with: pre-emergent in the fall, and post-emergent in the spring. Fall pre-emergent is strongly recommended as it will suppress the thousands of seeds poa annua puts out.
Over the counter treatment: Product containing Pendimethalin, OR dithiopyr OR benefin and trifluralin. Any product that is a pre-emergent for crabgrass will work. DO NOT put down pre-emergent in the fall in an area that you are going to seed with fescue! Always read the product label to see what it controls, what you can put it on, and how to apply it.
Poa annua is an annual winter grassy weed that seeds prolifically - as quickly as 6 weeks after germination - which qualifies it to be one of the biggest thorns in the sides of sports field managers, golf course superintendents and lawn care companies, not to mention homeowners.
Don't spread the seeds! If you have an area infested with poa annua, you should bag your clippings when you mow and be sure to rinse off lawn equipment before working on a different area.
If you have a poa annua problem, fall is the time to put down a pre-emergent or to start a lawn care program with a professional, especially if you have a problem in your fescue grass. After it's up, you can't treat poa annua in fescue, or you'll kill the fescue.
Poa annua grows in cool, damp areas and can't take much heat. In areas where it gets hot in the summer, poa annua will just die out. But you can be sure it will leave some seeds for next year!
Trivia: Poa annua flowers year-round, except in severe winter temperatures. Varieties of poa annua have adapted to climates world-wide, even the arctic tundra. Some golf courses actually have poa annua greens.