Is your turfgrass inexplicably turning any color but green? You might be dealing with a pesky lawn fungus known as anthracnose. What is this fussy fungus, why does it happen in the lawn, and what steps can you take to get rid of it? We’ll show you how to get rid of anthracnose in the lawn below.
Lawns that aren’t properly taken care of become the perfect place for pathogens and pests. Making the right moves in lawn care will help you curb this plant fungi problem for good.
A Fungus Among Us: What is Anthracnose?
Anthracnose is a disease caused by a group of fungi that affect a variety of vegetation from turfgrass to trees and everything in between. This fungal disease often starts spreading from leaves and twigs of trees, so it’s also referred to as shoot, twig, or leaf blight.
The fungus Colletotrichum cereale causes anthracnose in turfgrass. Common fungi that cause anthracnose in other plants include:
- Colletotrichum gloeosporioides
- Apiognomonia errabunda
- Discula destructiva
- Apiognomonia veneta
How to Identify Anthracnose in Your Lawn
Symptoms of anthracnose in the lawn manifest as what’s known as basal rot or foliar blight. Basal rot darkens and rots the leaf sheaths, crowns, and stolons. It’s much more damaging than foliar blight, which only affects the leaves–– leaves might turn a yellow or brown color and become extremely dry.
Note that symptoms of anthracnose can look different depending on what type of grass is affected.
For example, on annual bluegrasses, the symptoms of anthracnose appear as blotches of bright yellow in sporadic patterns across the lawn. On the other hand, creeping bentgrass affected with anthracnose appears as yellow, red, or bronze patches in any size. Even the temperature of your city can change the way anthracnose displays itself over time.
So, what’s a reliable way to spot anthracnose on the lawn? A general rule of thumb is to check the grass blades. Anthracnose starts with the crown region (the base of the grass where the root and shoot connect) of the plant. It’ll turn brown over time until the roots and lower stem base turn black.
When the stems and crowns turn completely back, the shoots become easily disconnected from the crowns. After this occurs, the leaves of the grass turn a yellowish color starting at the tip of the leaf moving towards sheathes and young leaves.
Some basic physical characteristics of anthracnose in the grass are:
- Yellow, red, and bronze patches of turf fading to brown over time
- Long, red to brown marks with yellowish halos on grass leaves
- Leaves and sheathes turning black
- The tissue of the grass crown looks water-logged
What Causes Anthracnose in the Lawn?
First and foremost, anthracnose is caused by several different fungi that affect different species of plants, vegetables, and fruits. But in the lawn specifically, the main culprit is Colletotrichum cereale.
Beyond the fungus itself, treating your lawn (or not treating it) has some sway over the manifestation and spread of anthracnose. All of these common lawn issues might contribute to conditions ripe for anthracnose:
- Hot temperatures and moist weather conditions
- Overgrown thatch
- Leaf blades exposed to water for long periods
- Drought conditions
- Bad drainage
- Cold temperatures of the early spring
- High foot or vehicle traffic in the lawn
- Soil compaction
- Improper fertilization
How to Treat and Prevent Anthracnose
Treating this difficult disease is more than a quick spray of fungicide. You’ve learned what causes anthracnose. Think of these causes as hints for treatment, from relieving compacted soil to improving fertilization.
Of course, you have the option of traditional fungi-killing chemicals, but you’ll need to combine preventative fungicide applications with the right lawn care routine. Turfgrass fungicides are less effective against existing anthracnose outbreaks, so fungicides should mainly be used to prevent anthracnose outbreaks rather than as a curative spot treatment.
If you were to use fungicides for anthracnose, use ones containing propiconazole or azoxystrobin with propiconazole.
Take these steps to curb this lawn-destroying nuisance.
Fertilize Properly
Water your lawn three to four days prior to applying fertilizers. This will ensure your lawn is moist enough to absorb the nutrients in the fertilizer. Make sure you fertilize your lawn at the right time, too.
Warm season-grasses should be fertilized in late spring or early summer. If you have cool-season grass, fertilize in the early spring or early fall. It’s a good idea to test the quality of your soil so you can make a more appropriate fertilizer choice and develop an ideal routine for your lawn.
Aerate the Lawn
Aeration helps relieve soil compaction. Compacted soil causes damage to your turf’s roots because the dense soil negatively impacts the lawn’s ability to hydrate, breath, and absorb nutrients. When you aerate the lawn, you create small holes in the soil that better allow the roots to receive what they need.
Some other interesting benefits of aeration beyond controlling lawn diseases are:
- Increases the deep growth of root systems
- Thins out thatch buildup
- Promotes better drainage
- Keeps the earthworms happy–– looser soil is better for earthworms who perform beneficial processes in the ground, like improving the structure of your soil and managing thatch buildup.
Mow the Grass Properly
Mowing isn’t as simple as going over the grass once or twice. You’ll need to make sure you’re cutting the right amount off for your grass type. Ensure your blades are sharp so cuts are clean and neat.
It’s also important to take into account the time you mow. An ideal time to mow your grass is between 8 and 10 a.m., or around mid-morning. This is because the moisture from the early morning has dried up a bit (it’s better to mow dry grass) and it’s not too hot just yet. Your grass will also recover over the heat of the day.
Mowing in the evening might leave your grass exposed to excess moisture. Excess moisture makes for a very attractive environment for anthracnose so mowing properly will avoid this scenario entirely.
And remember, don’t mow too low. Removing more than one-third of the grass blade’s height in a single mow may stress your turf.
Manage Thatch
Thatch can be beneficial for your lawn, but keeping it overgrown and messy is a breeding ground for fungi and disease. Thatch is a layer of dead and living plant material that sits above the soil’s surface. A small bit of thatch is okay for grass, but too much thatch buildup chokes out your lawn, keeping it from absorbing essential nutrients, water, and sunlight.
Too much thatch is a good place for anthracnose to hide and grow. Remove thatch from warm-season lawns in late spring or early summer and remove thatch from cool-season lawns in early fall.
Water Your Lawn at the Right Time
It’s best to water the lawn early in the morning, before 10 a.m. (ideally before 8 a.m.). This ensures proper moisture absorption before the afternoon sun evaporates the water.
Avoid mowing your lawn in the evenings. Why? Because your grass will struggle to dry at night, creating favorable conditions for diseases.
Plant Resistant Varieties
Depending on where you live (and what the weather is like) certain types of grass cultivars can resist fungal diseases. Learn whether you need to plant warm or cool-season grass in your area.
Keep in mind these grasses are commonly affected by anthracnose:
- Perennial ryegrass
- Bermudagrass
- Centipedegrass
- Kentucky bluegrass
- Fine-leaf fescue
- Zoysiagrass
- Tall fescue
Remove Grass Clippings
It’s important to remove your grass clippings when your lawn has an anthracnose breakout. Infected clippings spread the disease around the lawn. If your lawn is healthy, however, leaving behind your grass clippings is actually beneficial for the lawn, giving your turf a boost of nutrients.
FAQ About Anthracnose
Yes. Just as it affects your turf and trees, anthracnose also affects fruits and vegetable crops. Some helpful tips to manage anthracnose-causing fungi in the garden include:
• Harvest your fruits and vegetables regularly
• Remove infected plants, fruits, and vegetables
• Avoid getting soil on your crops
• Do not water the tops of crops when it’s humid and shady
• Remove all the plant debris at the end of the growing season
• Clean your garden tools after each use
Anthracnose spreads through spores, often carried by rain. It is able to spread throughout your lawn and plants within a week or two. It survives in soil without a host for up to nine months. It’s also known to overwinter, which is when an organism survives through a particularly cold and harsh winter.
While a fungus is a good culprit for a discolored or yellowing lawn, it’s possible something else might be affecting your lawn’s health. It’s good to be aware of the causes that change the color and texture of your lawn. Some common reasons for a yellowing lawn include:
• Animal urine such as dogs and deer
• Pests like grubs and chinch bugs
• Other lawn diseases like powdery mildew, dollar spot, and fairy ring
• Too much shade
• Nitrogen deficiency
• Too many harsh chemicals like pesticides and herbicides
Professional Help to the Rescue
As you can see, a lot of anthracnose management comes from properly treating your lawn. A healthy lawn care routine both prevents and gets rid of the fungi that cause anthracnose. If you’d rather not carve out hours at a time to nurse the lawn back to health, it might be time to hire a professional lawn care pro.
Main Image Credit: Shutterstock
