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How to Best Control Annual Bluegrass Weed

During the winter time, you would think lawn owners can get a little bit of a break from lawn maintenance and weed prevention since the cold weather usually makes it so weed seeds remain dormant. However, invasive plants like the annual bluegrass (also known widely as poa annua) actually grows and thrives in the winter time. Annual bluegrass have been known to give homeowners fits during the cool season and while controlling this weed can be tricky, it is possible to eliminate them from your lawn with the right technique and quality herbicides.


Annual Bluegrass Background Information

Like its name clearly states, annual bluegrass is an annual weed that is commonly found in lawns and occasionally even in gardens. It is also known as poa annua but perhaps because of confusion when it comes to pronunciation, the name annual bluegrass is the more common name for it. The plant is native to Europe but it has crept up everywhere across the world and is common on residential turfs. Compared to most turfgrasses, annual bluegrass green color is lighter than most and the plant also has coarser leaf texture and produces unsightly-looking seedheads. However it’s most distinguishing characteristic is the tall tasseled seed stalk of the annual bluegrass that will typically tower over the rest of the lawn and becomes visible in late spring or early summer. But, while this seed stalk can be tall, if it is cut short, it can still produce seeds.

Controlling this weed is rather difficult because the plant has the ability to produce several hundred seeds in one season, which can lay dormant for several years before sprouting. Annual bluegrass is typically a problem in residential yards because it dies back in hot weather, which can result in unsightly brown spots in the lawn during the height of summer. It also thrives during cool weather when most other lawn grasses are dying back, which means that it invades the lawn at these susceptible times.

Annual bluegrass has smooth leaves with a boat-shaped tip. It produces greenish white seed heads throughout its life cycle with the majority appearing during the spring months.  While annual bluegrass can be found growing in a wide range of conditions, the weed prefers areas with moist and/or compacted soil.

Before starting a weed control program, homeowners should bear in mind that complete eradication of annual bluegrass (or any weed for that matter) from the landscape is not realistic. A more practical approach is to control the weed by reducing the infestation to a tolerable level which can be done with a combination of cultural changes to the turf and chemical herbicides.


Annual Bluegrass Control Methods

Recommended Pre-emergent Control:


Annual bluegrass germinates in the late fall or early spring, so timing is critical to being able to effectively control it. We normally recommend to lawn owners to control annual bluegrass before they sprout with a pre-emergent herbicide. This is an herbicide that will prevent the annual bluegrass seeds from germinating. Herbicides must be applied in late summer/early fall before annual bluegrass germination. A second application can be applied in winter to control later germinating plants.


However, it is important to keep in mind that annual bluegrass seeds are tough and can survive many seasons without germinating. This method will work towards reducing annual bluegrass in the lawn over time. This will take a high level of persistence and diligence on your part as it will take repeated treatments to your lawn for multiple seasons in order to completely remove this weed. Also it is important to mention that pre-emergents will not work on annual bluegrass that has already emerged from the soil. That’s when applying post-emergent is best.


Recommended Post-emergent Control:


These selective post-emergent herbicides above are best for controlling annual bluegrass. Choosing the best one for you depends on your preference and budget and also it depends on the phase of the life cycle that the annual bluegrass is in. Herbicides will work best when the annual bluegrass is young. As the weed matures, they will be more resistant to chemicals which may require repeated applications.

If all else fails, and especially when the plant is dormant, you may have to resort to non-selective herbicides like glyphosate/roundup to eradicate the plant from your lawn but this should be regarded as a last-ditch effort.


Annual Bluegrass Tips and Recommendations

  • Use a hand-pump sprayer with a fan tip nozzle. Spraying a fine mist is best when applying herbicides to annual bluegrass so that entire plant if completely coated.

  • Remember that the label is the law. Be sure to look towards the instructions on the label for proper application and mixing rates.

  • When handling any pesticide be sure to wear the right protective equipment to cover your skin, eyes, nasal openings and mouth.

For more information on controlling annual bluegrass on your lawn and to get advice catered to your unique issue from experts, contact us at askapro@solutionsstores.com or call our customer service line at (800) 479-6583.

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