Miscellaneous

Poa Annua Control – Poa Annua Grass Treatment For Lawns

Poa Annua Control – Poa Annua Grass Treatment For Lawns


By: Heather Rhoades

Poa annua grass can cause problems in lawns. With a little knowledge and a little persistence, poa annua control is possible.

What is Poa Annua Grass?

Poa annua grass, also known as annual bluegrass, is a annual weed that is commonly found in lawns, but can be found in gardens as well. It is rather difficult to control because the plant will produce several hundred seeds in one season, and the seeds can lay dormant for several years before sprouting.

The identifying characteristic of poa annua grass is the tall tasseled seed stalk that will typically stand up above 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.

Poa annua grass is typically a problem in the lawn because it dies back in hot weather, which can make unsightly brown spots in the lawn during the height of summer. It also thrives during cool weather, when most lawn grasses are dying back, which means that it invades the lawn at these susceptible times.

Controlling Poa Annua Grass

Poa annua grass germinates in the late fall or early spring, so the timing of poa annua control is critical to being able to effectively control it.

Most people choose to control poa annua with a pre-emergent herbicide. This is a herbicide that will prevent the poa annua seeds from germinating. For effective poa annua control, apply a pre-emergent herbicide in early fall and again in early spring. This will keep the poa annua seeds from sprouting. But keep in mind that poa annua seeds are tough and can survive many seasons without germinating. This method will work towards reducing poa annua in the lawn over time. You will need to treat your lawn for many seasons in order to rid it completely of this weed.

There are some herbicides that will selectively kill poa annua in lawns, but they can only be applied by certified professionals. Non-selective herbicides or boiling water will also kill poa annua, but these methods will also kill any other plants that they come in contact with, so these methods should only be used in areas where you wish to kill plants on a wholesale basis.

Note: Chemical control should only be used as a last resort, as organic approaches are more environmentally friendly.

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Poa Annua – How To Control & Get Rid of Annual Bluegrass

Poa Annua – also known as Annual Bluegrass – is a winter annual grass that can spread very quickly. An infestation of Poa Annua is very noticeable as it begins to flower and push seeds. To say that this nuisance grasstype is less than desirable for lawn care nuts would be an understatement.

Controlling Poa Annua is not a one-and-done approach. The seeds of Annual Bluegrass can lay dormant in the soil for several years before emerging, so constant control and cultural practices are required for several years.

So that begs the questions, what is Poa Annua and how do I kill it and control it? This post should help you cool season grass owners.


Putting Poa Annua in its Place

Putting Poa Annua in its Place

A weed that can easily be mistaken for Kentucky bluegrass is known as Poa annua, or annual bluegrass. This grassy weed is extremely common throughout the United States and is well adapted to various locations, conditions and maintenance practices making it a weed that can be tough to get rid of. Perhaps the easiest way to identify this light green invader is by its tall seed head which produces tassels and rises above the typical home lawn, resulting in unsightly patches as seen in the images below.

A single Poa annua plant can produce hundreds to thousands of seeds, which can remain dormant in the soil for years and will typically germinate during the late summer to early fall. Poa annua grass germinates in the fall when soil temperatures drop below 70 degrees. Once the germination process begins, the weed will continue to grow throughout the spring and will then flower and die off in the summer. When the weed dies off from the heat of the summer, it leaves behind unattractive brown or bare patches in the lawn. The Poa annua weed can also continue to grow in the winter when most home lawns go dormant and will thrive in areas of the lawn that are damp, shady and compact due to its shallow rooting system.

Poa Annua Non-Chemical Control

Before moving to chemical controls, there are a few preventative maintenance practices homeowners can implement to allow their lawn to outcompete the annual bluegrass. Due to its shallow rooting system, the weed will thrive in areas of the lawn that are overwatered therefore, homeowners should attempt to water deeply and infrequently so that the shallow rooting system is unable to obtain the water it needs. It can also be beneficial to raise the mowing height for the lawn, as Poa annua is a shorter plant, which gives the lawn a chance to choke out the weeds. Creating a lawn that is dense and healthy can prevent weed problems from occurring. This includes maintaining a proper mowing, irrigation and fertilization schedule to meet the needs of the turf so that thin or diseased patches that are more susceptible to weeds do not have the chance to develop. Weeds will struggle to compete against a maintained, established lawn. Visit Lawnifi.com to learn more about how Lawnifi™️’s proper fertilization schedule will help your lawn become nourished and strong. Our Fall Fertilizer Box contains one bottle of Boost, Maintain and Recover, which work together to help your lawn get over the stressful heat of the summer as well as prepare for winter dormancy. Lastly, apply a pre-emergent in the late summer or early fall to prevent Poa annua from germinating. As previously mentioned, Poa germinates in the fall when soil temperatures drop below 70 degrees. To learn more, visit our How to Use a Pre-Emergent Herbicide in the Fall blog.

Poa Annua Chemical Control

If you have identified the problem early on and only a few weeds are present, Poa annua can be pulled by hand and may not grow back again. However, if Poa annua turns into a recurring problem or is too extensive to pull by hand, there are many chemical options that can control this issue. One pre-emergent control option is Prodiamine 65 WDG (active ingredient prodiamine), which can provide control for up to six months and can result in 70 percent of better control of Poa annua in just one application. However, if annual bluegrass has already established itself, a post-emergent herbicide will be necessary. A post-emergent option can be found with Southern Ag Atrazine (active ingredient atrazine). Revolver is also a good option.


Annual bluegrass — a serious spring weed problem in Virginia’s lawns.

Annual bluegrass puts on a showy display of its seedheads every spring just before it dies in our summer heat. What can be done now and in the future to better manage this important lawn pest?

Numerous questions have come into the Virginia Tech Turf Team’s offices in mid-April regarding chemical alternatives to control annual bluegrass (scientific name of Poa annua, often referred to as Poa or Poanna) in homelawns in the spring. You will recognize this plant by its light green color compared to most other turfgrasses, but more specifically by its prolific seedhead formation in mid-spring. Unfortunately, there is really nothing that can be done now other than to mow the turf to reduce seedhead numbers and improve turf uniformity. Most Poa behaves as a true winter annual plant that is, it germinates in the fall, produces seed in the spring, and dies. Hence, the plant is nearing death very soon, so any attempts at chemical control are pretty much pointless at this time. Poa is an annual problem because of the prolific number of seed that it produces, so you will never eradicate it from your lawn and landscape—you will only be able to manage it.

Though it is not of any help with the weedy mess you might have in your yard now, the best bet to reduce Poa populations for next spring is to plan on making a fall preemergent herbicide application in the first couple of weeks of September. Why not make a note of this on your calendars now so you won’t forget? This control strategy works well on both Poa and a whole host of other winter annual broadleaf weeds (for example chickweed, deadnettle, henbit, geraniums, etc.) IF you DO NOT plan on seeding any desirable turfgrasses next fall. The herbicides available for homelawn use do not differentiate between weed or turf seeds. If you must reseed a cool-season turf, then do everything you can to enhance turf establishment such that the new grass overwhelms the Poa simply due to the competition. Your keys to success in establishment are things such as proper testing and preparation of the soil, appropriate seeding rates, optimal seeding timing, and irrigation management. For those of you growing warm-season turfgrasses, you have the additional option of treating winter weeds with a non-selective herbicide such as glyphosate when the turf is fully dormant, an option not available in cool-season turfgrass stands.


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How To Control Crabgrass And Annual Blue Grass In Your Lawn

Crab grass can be a real pain, but there is another contender called Annual Bluegrass (Poa annua). In some areas the crab grass can be easy to identify and removed. Annual Bluegrass is a problem in lawns where the grass stays green all year long. Annual Bluegrass will throw seeds out all year long in some areas. In a St. Augustine lawn, this weed is easy to identify because it has a very fine grass blade and readily stands out in a St. Augustine lawn.

Getting rid of this weed can be a real issue because of the thin blades will resist any weed killer while the same weed killer will damage or kill off your St. Augustine grass. Even if you do manage to kill off this Annual Bluegrass weed, the seeds will come back to haunt you either in spring or in about 45-60 days.

Even in a Fescue or Bermuda lawn, this weed can be a challenge to get rid of. Using a pre-emergence at the beginning of the growing season can help reduce the growth but removing the weedy grass can be a labor of love. The only effective way I have found to remove the Annual Bluegrass from my St. Augustine is to pull it out, one by one. Once it has been removed, the application of a Pre-Emergence will help to control any new seeds that are in the soil or that have be “re-deposited” onto your lawn.

Weed killers are designed to help the homeowner get rid of the wide leafed weeds such as dandelions, purslane or plantain to name just a few. It is possible to do a surgical strike and kill off the Annual Bluegrass but any grass surrounding this area will also fall victim. The weed seeds will not be affected however, unless a pre-emergent has been applied and re-applied again as directed by manufacturer, which may be anywhere from 3-4 months out to 6 months, depending on the product used.

Bayer has a product called "Season Long" and is said to be effective for up to six months. This will work great for the weed seeds left behind, but since it is a selective herbicide, it will not affect the weed itself due to its narrow blades. A non-selective herbicide will do the job.

Crab grass can be a real pain, but there is another contender called Annual Bluegrass (Poa annua). In some areas the crab grass can be easy to identify and removed. Annual Bluegrass is a problem in lawns where the grass stays green all year long. Annual Bluegrass will throw seeds out all year long in some areas. In a St. Augustine lawn, this weed is easy to identify because it has a very fine grass blade and readily stands out in a St. Augustine lawn.

Getting rid of this weed can be a real issue because of the thin blades will resist any weed killer while the same weed killer will damage or kill off your St. Augustine grass. Even if you do manage to kill off this Annual Bluegrass weed, the seeds will come back to haunt you either in spring or in about 45-60 days.

Even in a Fescue or Bermuda lawn, this weed can be a challenge to get rid of. Using a pre-emergence at the beginning of the growing season can help reduce the growth but removing the weedy grass can be a labor of love. The only effective way I have found to remove the Annual Bluegrass from my St. Augustine is to pull it out, one by one. One it has been removed, the application of a Pre-Emergence will help to control any new seeds that are in the soil or that have be “re-deposited” onto your lawn.

Weed killers are designed to help the homeowner get rid of the wide leafed weeds such as dandelions, purslane or plantain to name just a few. It is possible to do a surgical strike and kill off the Annual Bluegrass but any grass surrounding this area will also fall victim. The weed seeds will not be affected however, unless a pre-emergent has been applied and re-applied again as directed by manufacturer, which may be anywhere from 3-4 months out to 6 months, depending on the product used.

Bayer has a product called "Season Long" and is said to be effective for up to six months. This will work great for the weed seeds left behind, but since it is a selective herbicide, it will not affect the weed itself due to its narrow blades. A non-selective herbicide will do the job.

This battle will have to be continued and the homeowner will need to be diligent and keep an eye out for this opportunistic weed.

Please share with us your experience with the weed Annual Bluegrass-Poa Annua & Crabgrass.


Watch the video: Poa Annua Weed Control in the Lawn