Annual Bluegrass

How to Get Rid of Annual Bluegrass (Poa Annua)

Annual Bluegrass, or Poa Annual as some people call it, is a tricky winter annual weed that can be difficult to control and and near impossible to completely erradicate. One of the reasons for that is because Poa Annua will produce seed heads through out its life cycle and especially during the spring months. Poa Annua goes dormat and germinates during the fall months and will start to flower and produce seeds in the spring months as mentioned earlier. It grows well in cooler, moist conditions and often in compact soil. The heat brought on by summer puts stress on it and it will help kill it all but not completely eliminate it. What you apply and when you apply certain herbicides is very important to control your population. 

Characteristics

  • bright green leaf with boat-shaped tip
  • leaf has a smooth texture
  • low growing and tends to grow in bunches
  • winter annual weed
  • likes to grow in compact and moist areas
  • seed heads are greenish to white/off-white color

Treatment

Selective Herbicide

    The most effecitve method in knocking down your Poa Annua population is though the use of selective herbicides. These herbicides are specifically designed to target your Poa Annua and not the surrounding vegetation. Selective herbicides Poa Annua tend to be more on the expensive side so figuring out which is best for you and your lawn is very important. As of recent, Poa Annua has developed resistance to some herbicides so long term control may involve rotation of herbicides. Here are some tips for selecting the right product:

    • Identify what kind of grass you have in your lawn. Some products are not safe for sensitive grasses such as St.Augustine so this will help narrow your search.
    • Many of the chemicals are limited to warm season grass such as zoysiagrass, bermudagrass, centipede, and St. Augustine. 
    • Determine the scope and severity of your Poa Annua infestation. If you have a small lawn and a light infestation, that $300 bottle may not be for you.
    • If you have properly identified the grass in your lawn you can use our filter options to find products that are safe for you lawn:

     

    Non-Selective Herbicides

    • A non-selective herbicide will kill any vegetation that it touches.
    • Apply ONLY when your surrounding turf grass is dormant (all green is gone) and spot treat trouble areas.
    • Apply when there is a low chance of rain to avoid runoff of chemical to other vegetation.
    • Recommended ProductsGly Pho-Sel Pro Dry 75 SGEraser Max, and Alligare Glyphosate 5.4 

    Prevention

    • Application of pre-emergent herbicides is the most effective way to control annual bluegrass.
    • The first application needs to happen in late fall/early winter before the seed germinates.
    • Apply is when the soil temperature reaches around 70 degrees.
    • A second application is recommended for seeds that germinate late.
    • Pre-emergent herbicides only prevent germination. They do not get rid of an established population.
    • Recommended Products:  Prodiamine 65 WDG, Dithiopyr 40 WSB, and Hi-Yield Turf & Ornamental Weed & Grass Stopper  

     

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