How to Identify Poa Annua

 Poa Annua is a light greenish color, has smooth leaves, and produces greenish white seedheads. It is easy to confuse regular grass seed heads with the thought that it may be Annual Bluegrass. 

  • A few more characteristics that will help you identify Poa Annua:
  • Leaves folded in the bud
  • Forms thick patches in lawn
  • Produces seed heads when it is growing
  • Auricles are not present

Poa Annua Life Cycle

 Poa Annua is a winter annual and will not grow over one feet tall. It dies out during the summer if there is intense heat. Poa Annua starts to germinate during the late summer and early fall timeframe. It will go dormant during the winter and will start growing actively starting at the end of April.  Poa Annua will not always die out on its own. If we have a mild winter, herbicides will be needed to get Poa Annua out of your lawn!

Poa Annua Pre emergent Control

 The best pre-emergent herbicide that we have found to be the most effective at killing Poa Annua is Prodiamine 65 WDG (Generic Barricade). Applying a Pre-emergent before Poa Annua germinates is the easiest way to control Poa Annua. A Pre-emergent herbicide creates a barrier below the grass, so the weeds will be stopped before they can emerge from the soil. To be effective, the entire area where you have seen annual bluegrass (poa annua) must be covered with the correct amount of pre-emergent herbicide. In most regions, Poa Annua will germinate when soil temperatures go below 70 degrees. This means that pre-emergent should be applied anywhere in the timeframe of August 15- September 15 to be the most effective.

Poa Annua Post Emergent Hericide

After Poa Annua germinates it becomes difficult to kill. It is very hard to find a herbicide that will kill the poa annua but not the grass surrounding it. The only herbicide we have found that works is Prograss EC Herbicide. It is very expensive, but if you want quick results, it is the only herbicide we know of that works. Prograss EC Herbicide will control Poa Annua from the time it germinates and during the time when it is growing. Prograss EC Herbicide does not kill Kentucky Bluegrass, St. Augustinegrass, bentgrass, or perennial ryegrass. However, it does kill bermudagrass, so do not apply it on or around bermudagrass if you do not want to kill it.

If you do not mind killing a little of your grass around the areas where the Poa Annua is present, Roundup Weed and Grass Killer-Super Concentrate will be a much more cost effective option. It is important to buy the super concentrate which includes more glyphosate which will kill the poa annua faster.

Poa Annua Cultural Control 

Avoid Overwatering: Poa Annua grows very well in highly irrigated areas. If Poa Annua is taking over your lawn, stop watering, and it possibly will die off.

Set Mower Deck High: Poa Annua does not like being cut short. Cutting your grass short will make it hard for Poa Annua to compete with the grass surround it.

Let heat kill the Poa Annua: Poa Annua will start to die once temperatures are consistently over 85 degrees. If it is a hot summer, the poa annua may die on its own.

Aerate: Poa Annua grows well in lawns that are compacted. Reduce compaction in your lawn, and the grass should over take the poa annua.