Perennial Forms of Annual Bluegrass

Sometimes you just want to cry. Lawn warriors valiantly and tenaciously trying to control annual bluegrass with pre-emergent chemicals will be discouraged to learn that this weed also comes in a >perennial< form. The darn thing has so much genetic variability that it eventually figures out how to get around weed preventers. It’s done it so many times that  annual bluegrass has become perennial for all intents and purposes.

Does that mean it has become impossible to control? No. it does not!

Annual bluegrass can still be controlled with a correctly applied pre-emergent product and a lawn grass that is properly managed, particularly regarding mowing height and frequency plus fertilizer applied in the proper amount and at the right time.

If you want a little chemical help after the weed has emerged in spring. Imazaquin (Image for Nutgrass) is labeled for use in winter on all grasses except fescue to control annual bluegrass. Since Image must be absorbed by roots, control may not be evident for several weeks.

Professional herbicides like Revolver(foramsulfuron), Tenacity(mesotrione), Poa Constrictor(ethofumesate), or Monument(Trifloxysulfuron-Sodium) may be considered. These products are used by professionals and are available to homeowners, but they are expensive. That said, you have to be very careful to

Remember: read and follow the label

on each one. They can be used on some lawn grasses but not others and timing the application correctly is important. You have to be REALLY careful with mixing. Remember that “annual” bluegrass is a misnomer. There are biotypes that behave more as a perennial plant and some are resistant to these products.

There is no silver bullet for annual bluegrass control.

see Controlling Poa annua in Sports Turf