Why Do I Have Poa Annua (Annual Bluegrass)? Poa annua (annual bluegrass) is an annual grass that is being noticed more this month due to the large amount of tan colored seed heads the plant is producing now. It usually stands out in late April into May. The above-normal ground temperatures we had a couple… Read more »
Poa annua (annual bluegrass) is an annual grass that is being noticed more this month due to the large amount of tan colored seed heads the plant is producing now. It usually stands out in late April into May. The above-normal ground temperatures we had a couple weeks ago have caused it to produce a seed head on some plants earlier this year.
Poa annua is a wild annual grass. While it typically grows in areas that have poor compact soil and where your desired turf is thin or nonexistent, it can be found anywhere, even in the middle of the yard. However, it is a hardy plant and can grow in poor conditions where desirable turf will not. This is why you often see it in compact areas of the lawn. For example; along roadways, Devil Strips (strips between side walk and roadways) and, oddly enough, along the sides of driveways where you often walk on turf to get in and out of the vehicle. These areas are often heavily compacted making it difficult for desirable turf to flourish.
Poa annua actually germinates in the fall starting in late August through the winter; the same time you seed Fescue in this area. This is why pre-emergent applications for Crabgrass in January, February, and early spring do not control poa annua. Poa annua was too mature when the pre-emergent applications were applied so has no impact on control. Poa annua will generally end its life cycle in Late May and June. It is a prolific seeder and seed is generally viable the following year.
We control about 70% of poa annua in warm season (Bermuda, Zoysia and Centipede) turf by applying a product in the fall. We utilize a split application of this product which provides good control. We have a product that can be applied in November and again in December to control about 75% of poa annua in Fescue. Both applications are required to get roughly 75% control.
You will know if your Bermuda, Zoysia, Centipede or St. Augustine received winter damage by the end of May. In the Transitional Zone, we do not consider a warm season turf completely out of dormancy and actively growing till the end of May. Sure, some will look green or somewhat green before then but they are not actively growing yet. Several new varieties of Bermuda and Zoysia have the characteristics of breaking dormancy earlier and staying active longer into the fall. Centipede tries to break dormancy early and that is why Centipede turf is commonly damaged due to a late frost or cold spell in spring. Ground temperatures in May are generally conducive for 24-hour plant growth and activity giving us a better picture of potential warm season turf injury.
If you are really concerned about a part of the lawn that just isn’t looking right, there is something you can do before May: Cut out a small piece of the lawn and bring it inside in front of a window that is getting at least six hours of sunlight. Be sure to dig at least 3” of soil with your sample. Wait approximately two weeks and if you observe greening, the turf is probably fine. If no greening is observed by three weeks, turf is probably damaged.
A misconception with broadleaf weed control is that the weed should turn brown after treatment within a couple days and die. However, more times than not, this is not the case and most weed species may take a couple weeks to show signs of control. In fact, signs of control may not even be seen with the plant turning brown. More often the plant will just start to shrivel and disappear leaving a very small skeleton.
Moss continues to be a major topic of discussion with property owners because of the above-normal rainfall for the past two years, along with other site conditions conducive for moss development. Mosses generally do not kill grass, but they will take over areas in the lawn where turf is thin or unable to flourish and grow properly. Conditions that create moss are excessive shade, poor draining, compact soils and excessive moisture not allowing the soil to dry properly. Conditions that create moss also create a poor growing environment for quality turf.
Moss is a non-vascular plant and is not controlled by regular weed controls. There is not a reasonable chemical control option to remove moss. Moss is controlled by eliminating the conditions that create it.
Large patch fungus can be active and damaging on Zoysia, Bermuda, Centipede and St. Augustine grasses in spring and fall. Fairway Green is seeing more cases of this disease every year in our area. This disease is similar to brown patch fungus on Fescue.
Large patch fungus needs to be controlled with two applications of fungicide in the spring and fall when ground temperatures are between 50 and 70 degrees. Damage occurs before you are aware you have it and is not visible until green-up in the spring. Preventative fungicide in the fall and early spring is the only way to control this disease.