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How to Keep St. Augustine Out of EMPIRE Zoysia Lawns

When it comes to regular lawn maintenance, getting your lawn to look as good as possible takes a lot of work. This hard work can pay off when your lawn stands out from the rest of the yards on your block. However, you may notice your neighbor has a different kind of grass than yours. In fact, it is not uncommon for their grass to actually start growing into your own. This can especially happen if your neighbor’s St. Augustine lawn starts to encroach into your EMPIRE® Zoysia lawn. Not to worry though—this can easily be resolved with several different methods.

The best way to keep St. Augustine out of EMPIRE is to keep your EMPIRE lawn mowed low at around 1.5–2 inches in height. Overtime, the St. Augustine will eventually be choked out as St. Augustine does not perform well at such a low height. Fusilade II Herbicide is the best chemical control option. Although it’s not labeled to kill St. Augustine grass, it’s also not labeled to treat St. Augustine. Fusilade II will knock the St. Augustine back without harming the EMPIRE lawn if used appropriately.

Although this Sod University article primarily focuses on keeping St. Augustine out of EMPIRE Zoysia, the same tips and tricks can be applied to any type of zoysia lawn. Read below to learn more.

How does St. Augustine get into EMPIRE Zoysia?

It is not uncommon for other grasses to grow into your lawn. Grasses can spread laterally with the use of rhizomes and stolons and are considered to be an “invasive species” because they can grow into areas they aren’t wanted. St. Augustine is a stoloniferous grass, meaning it will naturally spread with the use of its stolons.

Stolons are above-the-ground stems that grow along the surface of the soil and create clones of the original plant on the end of them. The clone plant then sends down roots and establishes itself as an independent plant before repeating the process. This is usually what you’re looking at if you notice St. Augustine invading your EMPIRE Zoysia lawn. It should also be known that St. Augustine naturally has a more aggressive growth habit than most zoysia grasses.

Pictured above from left to right: A St. Augustine stolon growing across bare soil, and CitraBlue® St. Augustine growing into InnovationTM Zoysia.

Here are a few photos demonstrating St. Augustine that’s starting to invade into a Zeon® Zoysia lawn. Although the Zeon is dormant, you can still see the St. Augustine (green) as it starts to creep in.

Cultural Treatment Methods

In a previous Sod University article on Sod U’s Most FAQs, we cover the topic of keeping a neighbor’s yard from growing into your own. Cultural and non-chemical methods like the addition of a fence, hedges or a plant bed can help with keeping any sort of grass out of your lawn. If the St. Augustine invasion isn’t severe, you can go about hand-pulling the St. Augustine stolons. Good communication with an understanding neighbor is also suggested. Make sure your neighbor is aware of the situation so that you can brainstorm a few possible solutions.

One of the most effective ways to keep St. Augustine out of EMPIRE, however, is to mow it between 1.5–2 inches in height. EMPIRE will thrive at this mowing height whereas St. Augustine, in comparison, generally performs best at a taller height. When St. Augustine is mowed at this shorter height, the EMPIRE has the upper-hand advantage of choking out.

Chemical Treatment Methods

Lastly, there are a few chemical treatment methods you can go about using. One suggestion is to use a non-selective herbicide to spot treat the areas where St. Augustine is growing. A non-selective herbicide, as its name implies, kills all vegetation it comes in contact with. This includes your EMPIRE Zoysia. Be careful not to get this on your zoysia lawn. An example of a non-selective herbicide is glyphosate.

When it comes to selective herbicides, which only kill the vegetation they are labeled to kill, the general idea is to locate and apply an herbicide that will kill St. Augustine grass without harming zoysia.

Quinclorac 75 DF is a an herbicide that is not supposed to be used on St. Augustine grass. However, it may not 100 percent kill off the St. Augustine and it may also damage zoysia at a lesser extent than the St. Augustine. The problem with this is that certain St. Augustines recover from damage at a faster rate than zoysias. The St. Augustine will recover and potentially continue to grow into the damaged zoysia.

The best and most effective herbicide for driving out St. Augustine from EMPIRE Zoysia lawns is Fusilade II Herbicide. However, it is highly suggested you follow the label’s application instructions closely so that it doesn’t harm the zoysia. When too much is applied, it will damage your zoysia lawn, which defeats the purpose of application.

With that being said, the safest way to remove St. Augustine from your EMPIRE Zoysia is by hand-pulling the stolons. Although they are fairly easy to pull out, this takes a longer amount of time and the St. Augustine will continue to come back. However, hand-pulling St. Augustine stolons guarantees the safety of your EMPIRE Zoysia lawn.

Be sure to check out a few related Sod University blogs on Weed Control in Your Zoysia Lawn and How to Remove Invading Bermudagrass and Centipede from a Zoysia Lawn.

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