It’s that time of year again. Your dormant bermuda or zoysia turf is overrun with green patches of annual bluegrass, or as it is called by its scientific name, poa annua.
Annual bluegrass is a winter annual grassy weed that first germinates in the fall, usually in October. It will continue germinating during warmer periods of the winter and will grow to several inches tall by the spring. It then will begin producing large amounts of seeds before dying off in May. The seeds, of course, germinate again the following October and the cycle starts again with a more significant infestation. Cutting the grass close does not help because poa annua will form seed heads very quickly after mowing. It also seems to grow more prolifically in wetter areas of your lawn.
Fortunately, there are multiple herbicide control strategies that are usually successful. First, an effective pre-emergent applied in early October can stop most of the problem before it even starts. Pre-emergent herbicides kill new seedlings as soon as they germinate. You likely will never even see them.
For the small percentage of seedlings that survive the pre-emergent barrier, there are effective post-emergent herbicides. Also, it often can take 2-3 applications for complete eradication, so be patient with our efforts in eliminating this weed from your dormant bermuda and zoysia turf.
It is important to note that because annual bluegrass is a grassy weed, the standard broadleaf weed killing herbicides that kill other weeds such as clover, chickweed, dandelions, etc., are useless against annual bluegrass. It requires special weed killers that target grassy weeds. Many other companies do not include post-emergent annual bluegrass control with their basic program and upcharge you for it. We do include it with our basic program because it is such a nuisance and we want our customers’ lawns looking as good as possible as a reflection of our company’s work.
So don’t let the poa annua trouble you too much. Be patient and let the herbicides work and your dormant bermuda or zoysia turf will be weed-free again soon!