Annual bluegrass is a persistent problem in lawns throughout the united states. Annual bluegrass or poa annua and commonly called spear grass is most notable for seed heads throughout the lawn in late spring and early summer. The seed heads will appear even on a neatly mowed lawn and break up uniformity. These seed heads will release and create the following years annual bluegrass crop.
All of this on its own is not a huge problem but annual bluegrass can not tolerate any heat and dies every summer, leaving behind large, brown patches and bare areas. Thus annual bluegrass is more of a weed than a turf grass. If you have noticed a grass type with white seed heads in the lawn that perishes every year and is very unsightly it is most likely Annual Bluegrass.
Controlling annual bluegrass requires a special process that may seem strange but I have done it and it works, and no it is not round up!
To control annual bluegrass you need to apply a pre-emergent crabgrass control in the fall.
The product I used to control poa annua is predemethlyn but barricade and dimension are also labeled for its control with a fall treatment. The reason this works is that annual bluegrass germinates in the late summer or early fall when temperatures drop and survives until seeding the following year. When you apply a pre emergent in the fall it prevents the weed from germinating therefore ending the cycle of annual bluegrass. Apply your control product the same way that you would in the spring for crabgrass control and be sure to follow the labels directions for poa annua.
A few key points to keep in mind-
- You can not do any fall seeding with this treatment, it will prevent turf seed from germinating.
- Also this treatment will not prevent the following years crabgrass so be sure to make proper plans to make another pre-emergent treatment for crabgrass the following spring.
If you have your own experience with poa to share or tips and tricks that work for controlling annual bluegrass please comment below. Thanks for reading!