January 20, 2022

Pre-emergent for Bermudagrass

What is Bermudagrass?

Bermudagrass, also known as wiregrass or devil’s grass, is a perennial warm season grass commonly used throughout southern regions of the US and into transition zones. Bermuda’s growing season is from late spring until early fall. Bermudagrass requires full sun and well drained soil.

Bermudagrass is highly regarded for its exceptional heat and drought tolerance and ability to repair itself quickly. This combination of desirable attributes leads to this grass variety’s popularity.

Preventing Weeds in Bermudagrass

Controlling weeds in your lawn begins with proper management practices that encourage healthy turf. Since seeds need sunlight to germinate, a healthy, dense turf will shade the soil which allows less sunlight to reach the weed seeds to begin with. Dense grass also minimizes the space available for weeds to establish themselves.

Proper Lawn Management

Homeowners often wish to rid their Bermuda lawns of weeds because they are unattractive and disrupt the uniform appearance of their lawns. Not only are they unsightly, but weeds will compete with your Bermudagrass for sunlight, nutrients, and moisture.

Best management practices include proper:

Soil testing analysis and amendments
Sod selection for your space
Mowing height and frequency
Watering rate and frequency
Fertilization based on soil test results
Aeration to reduce soil compaction
De-thatching as needed

* See our Bermudagrass Guide for more detailed information on Bermuda’s maintenance schedule

Control Weeds in Bermudagrass with Pre-emergent Herbicides

Weeds may still appear even if proper lawn management strategies are in place. If you are unable to pull weeds by hand you may need to apply herbicides.

What are Herbicides?

Herbicides are substances that are toxic to plants and are used to destroy unwanted vegetation.

If you decide to use herbicides to help control weeds in your lawn it is important to know what weed or weeds you are trying to control. Your state or local Extension office will be able to help identify common weeds in your area.

*Before using any herbicide, read the entire label carefully and follow directions precisely for rate and timing. Make sure that the herbicide is tailored to the type of weeds you need to eradicate and won’t harm the surrounding grass or ornamentals.

How do pre-emergents work?

These effective treatments are formulated to prevent germinated seeds from maturing, stopping weeds before they are visible. After treatment, fewer weeds sprout, producing fewer seeds, and the cycle continues. With regular pre-emergent applications, property owners or their lawn maintenance service can make a significant dent in a lawn’s weed population.

When to apply pre-emergant to Bermudagrass

Pre-emergent herbicides create a barrier that keeps weeds seeds from germinating, therefore pre-emergent should be applied to the soil before weed seeds germinate. Knowing when to spray liquid herbicides or apply granular herbicides is important. Using these chemicals in the wrong temperatures can make them ineffective.

It is important to target the weed(s) you wish to eliminate at the right time of year. Pre-emergent should be applied based on the weeds you want to prevent for the next 3-5 months.

Pre-emergents provide good control of many annual grassy weeds, like crabgrass and annual bluegrass; and can also control some annual broadleaf weeds.

Spring Pre-Emergent Application

In the spring, pre-emergent should be applied to your Bermuda lawn in late February or early March before soil temperatures reach 55°F. Soil temperatures will typically reach 55ºF when the air temperature is between 65-70ºF for four consecutive days.

Depending on the type of pre-emergent used a second treatment may be needed 8-10 weeks after the initial application to provide season long control of annual grassy and broadleaf weeds.

Fall Pre-Emergent Application

In the fall, pre-emergent should be applied to Bermudagrass lawns to control winter weeds , such as henbit and chickweed, in late September to early October when air temperatures reach 65-70ºF for four consecutive days.

Again, for season long control, a second treatment may be needed 8-10 weeks after the initial application.

Important:

Temperatures can vary greatly from year to year, so it is crucial to monitor air and soil temperatures and apply management practices based on the current year’s climate.
Monitor climates in late winter/early spring when sod is coming out of dormancy and early fall when first frosts are forecasted and plan your herbicide application in advance.

Tips for Pre-emergent Success

Do not apply pre-emergent to new sod.
New sod should never have pre-emergent applied. We suggest waiting until the sod if fully rooted before using pre-emergent on new sod.

Do not apply pre-emergent if you plan to seed or have recently seeded your lawn.
Pre-emergents stop seeds from growing. Typically, you will have to wait four months after an application to seed your lawn.

Do not apply to damaged turf.
Pre-emergent should not be applied to lawns affected by drought or pest damage.

Do not apply to putting greens.
Golf courses find pre-emergents ineffective on putting greens due to the high traffic of the areas.

Water after application.
Water is required after application to move the chemical below the ground’s surface where seed germination occurs. For best results, apply before an expected rainfall.

Be sure to use the right herbicide for your grass type.
Most pre-emergents are specifically formulated for specific turf varieties and weed types.

Apply pre-emergent herbicides evenly.
If you miss spots, seeds will sprout and weeds will grow.

Post-emergent Herbicides for Bermudagrass

Apply a post-emergent to your Bermudagrass as needed to control exisiting weeds. Generally, do not apply post-emergent herbicides during your lawns spring green up.

According to Clemson Cooperative Extension, “Bermudagrass is sensitive to certain herbicides, such as 2,4-D, not only during spring green up, but during hot summer temperatures.