There are a ton of different types of lawn fungus out there, but no matter which one you’re talking about, you don’t want it to be on your lawn.
Any type of lawn fungus will negatively affect the appearance of your lawn; some will cover your lawn with dead-looking patches, and some will cover your grass in gross slime, but regardless of which fungus affects your lawn, you’re going to want to get rid of it.
Today we’ll be talking about how to identify various types of lawn fungus, how to effectively deal with them, and what you can do to prevent your lawn from being affected by fungus in the first place.
Table of Contents
Common Types of Lawn Fungus and How to Deal with Them
Let’s get right into it and go over several of the more common types of lawn fungus you might encounter.
Lawn fungi can affect the appearance of your lawn in a number of different ways, and they all grow in different conditions on different types of grass and require different methods of treatment to get rid of them. We’ll walk you through what each type of fungus looks like, the types of conditions they like to grow in, and the best methods for dealing with each specific type of fungus.
Brown Patch
Brown patch fungus is one of the most common fungi that affect cool-season grass, but many warm-season grasses can catch a case of this fungus as well. Some of the types of grass most commonly affected by this fungus are:
- Perennial ryegrass
- Bermuda grass
- Tall fescue
- Fine fescue
- Kentucky bluegrass
- St. Augustine grass
Brown patch fungus can occur any time between the start of spring and the end of fall, depending on where you live; this fungus tends to favor temperatures between 65-70 degrees Fahrenheit. Factors like overfertilizing your lawn or too much moisture caused by an abundance of wet leaves, high humidity, or overwatering can also cause this type of fungus to grow.
A lawn affected by brown patch fungus will have large circles of dead, dry grass, which can be either mostly circular or in irregular shapes. These patches can be up to 3 feet wide at the most, and the outer edge of these patches will often be a darker color than the interior.
Since this fungus is so common, we’ve written a more detailed guide about the Brown Patch Lawn Fungus here.
How to Treat It
You can prevent brown patch from occurring by not overwatering or over-fertilizing your lawn, but if your lawn does develop a case of brown patch, then cut back on the amount of water and fertilizer you’re using on your lawn, and your lawn will likely be able to recover on its own.
If that doesn’t work, then your only option is to use a fungicide on your lawn. To deal with brown patch, try and find a fungicide that uses fludioxonil as its main active ingredient.
Pythium
Pythium is a range of several different species of fungi that mainly affects cool-season grasses. Types of grasses affected by pythium include:
- Perennial ryegrass
- Bluegrass
- Bentgrass
- Fine fescue
Pythium tends to affect lawns from early summer to the start of fall when the temperature and humidity are at their highest. Factors like compacted soil, not enough direct sunlight, and overwatering/overfertilizing can increase the speed at which this fungus spreads.
Pythium takes the appearance of small orange spots, usually 1-3 inches in diameter, that cover the surface of your lawn. Eventually, these spots will start growing mycelium, which looks like small patches of cobwebs.
How to Treat It
If your lawn has a case of pythium, then you’ll want to use a fungicide to get rid of it. Look for a fungicide containing mefenoxam as its active ingredient.
Dollar Spot
Dollar spot fungus is a common fungus that affects many types of grasses. In particular, this fungus tends to target:
- Centipede grass
- Bentgrass
- Perennial ryegrass
- Fine fescue
But there are also several types of grass which can still be affected by dollar spot (albeit less frequently):
- Tall fescue
- Zoysia grass
- Bermuda grass
- Kentucky bluegrass
Dollar spot can occur at any time between late spring and fall, but it’s most common in the summer. It can be caused by under fertilizing your lawn, by an excessive buildup of thatch, or by too much/too little moisture in your lawn.
This fungus gets its name because it first manifests as circles of yellowish-tan grass, about 1 inch in diameter (the size of a silver dollar). Over time, these circles will grow in size and eventually merge into irregular patches.
How to Treat It
Since one of the main causes of this fungus is under fertilization, using a fungicide to treat dollar spot usually isn’t necessary. In most cases, all you need to do is apply some extra fertilizer to your lawn. Try and find a nitrogen-based fertilizer for this task.
Summer Patch
Summer patch, as the name implies, tends to affect grasses during the summer. It mainly tends to affect these grasses:
- Fine fescue
- Kentucky bluegrass
- Bentgrass
- Perennial ryegrass
This fungus grows best in particularly high temperatures, but its growth is also supported by factors like compacted soil, poor drainage and excessive water in your soil, and cutting your grass too short.
Summer patch takes the appearance of patches of grass that appear wilted and turn yellow or brown as time progresses.
How to Treat It
Unfortunately, if you’re noticing the signs of summer patch on your lawn, then pretty much the only thing you can do is irrigate your lawn to loosen up compacted soil and help your lawn drain better. There exist fungicides that prevent summer patch, but none that can treat it after it has already appeared on your lawn.
Look for a fungicide containing propiconazole if you want to help prevent summer patch from returning the following summer. You should apply this fertilizer in the late spring or around when the outside temperature first hits 65 degrees.
Snow mold
There are a couple of different types of snow mold that we’ll be going over; pink snow mold and gray snow mold. As you might have guessed, these two types of fungus tend to grow in places that get cold enough for snow and affect mostly cold-season grasses.
Both types of snow mold tend to grow when it is cool and moist on your lawn, and despite their names, neither of them necessarily need snow in order to grow. This fungus might also grow if you’ve overfertilized your lawn with nitrogen, if your lawn has too much shade, or if your lawn has poor drainage.
Both types of snow mold result in patches of grass that appear matted and are covered with mycelium. The difference between these two types of fungus is that pink snow mold tends to grow whitish or pinkish mycelium, while gray snow mold grows gray mycelium.
How to Treat It
In general, both types of snow mold tend to go away on their own when the temperature outside gets warm enough. But you can also speed up the recovery process by raking your lawn to aerate it, and you should also mow your lawn down to a shorter length than you normally do. Removing any thatch that has built up on your lawn will also help.
If your lawn is affected by snow mold every year, you can use a fungicide containing thiophanate-methyl as a preventative measure.
Rust Disease
Rust disease can be caused by a variety of fungi. This type of disease most commonly affects:
- Zoysia grass
- Ryegrass
- Kentucky bluegrass
- Tall fescue
This type of fungus tends to crop up between late spring and early fall, in temperatures between 68-86 degrees Fahrenheit. It may also appear as a result of drought or high humidity, or it may appear if your lawn is too shady or under-fertilized.
To spot rust disease, look and see if there are any patches of thinning, yellowish grass. It may also manifest as small yellow flecks on individual blades of grass. As the disease progresses, your lawn will become covered in a yellow-orange powdery substance that rubs off onto your shoes or gardening equipment.
How to Treat It
Rust disease tends to occur when your lawn isn’t being maintained properly, so if you start noticing the signs of rust disease, then it most likely means that you need to be watering and fertilizing your lawn more regularly. If your lawn’s appearance still doesn’t improve after this, you should try using a fungicide containing propiconazole to deal with rust disease.
Red Thread
Red thread is a fungus that usually affects cold-season grasses, as it tends to thrive in areas where the days are warm and the nights are cool. The types of grasses that are most commonly affected by red thread are:
- Perennial ryegrass
- Fine fescue
- Bluegrass
- Bentgrass
Lots of other factors can cause red thread to grow, including compacted soil, under fertilization, and high humidity or excessive amounts of wet leaves left on your lawn.
Red thread is pretty easy to spot; just look for patches of bleached, reddish grass on your lawn. The patches can be small or relatively large but generally not more than 2 feet wide
How to Treat It
Fully treating a case of red thread usually takes a couple of years or so, but in most cases, you can do it entirely without fungicides. Just make sure to regularly aerate your soil and fertilize it with nitrogen.
Gray Leaf Spot
Gray leaf spot is a fungus that primarily targets:
- St. Augustine grass
- Tall fescue
- Perennial ryegrass
Gray leaf spot usually grows in warm, wet conditions and may also occur on lawns that are overwatered/overfertilized, too shady, or lawns that aren’t getting enough air circulation.
As the name implies, gray leaf spot first manifests as grayish-tan spots on the blades of your grass.
How to Treat It
The best way to treat gray leaf spot is to maintain your lawn in the way recommended for your specific type of grass. Adjust the amount of water and fertilizer you use on your lawn and perform regular aeration, and in most cases, your lawn should go back to normal.
You can use a fungicide containing fluoxastrobin, azoxystrobin, or pyraclostrobin to temporarily treat instances of gray leaf spot.
How to Prevent Lawn Fungus
You can save yourself the hassle of having to deal with lawn fungus by taking pre-emptive measures to prevent lawn fungus from appearing in the first place. Let’s go over some of the things you can do if you want to keep your lawn always healthy.
Aerate Your Lawn
Aerating your lawn involves making numerous small holes all over your lawn to deal with compacted soil and help the roots of your lawn get enough nutrients. You can use a handheld aeration tool to easily aerate smaller yards.
Dethatch Your Lawn
Dethatching is the process of removing thatch from your lawn. Thatch is a buildup of mostly-dead grass that accumulates on your lawn and prevents air and water from circulating properly within your lawn.
A dethatcher is essential for removing thatch from your lawn. This one is electric and uses a rotating barrel lined with steel tines to dig into your lawn and remove the layer of thatch. It can also help keep your lawn aerated.
Water and Fertilize Your Lawn Correctly
The best time to water your lawn is in the early morning since this allows your lawn to sufficiently dry out throughout the day. In general, you shouldn’t use more than 1 inch of water per week on the surface of your lawn.
Lawn fungi can occur if you over/under-fertilize your lawn, so always distribute your fertilizer as instructed by the manufacturer. You can use a fertilizer spreader like this one to ensure that your fertilizer is distributed as evenly as possible over the surface of your lawn.
Use Good Mowing Practices
Mowing your lawn to the correct height and keeping your mower blades sharp goes a long way in helping to prevent your lawn from catching a fungus. A robotic mower can ensure that your lawn is always trimmed to the right height and at the right time without any extra input from you; just make sure you regularly maintain it so that it always functions as it should.
Perform a Soil Test
Using a soil testing kit, you can identify if there are factors in your soil that are making your lawn unhealthy. This soil tester can measure your soil’s acidity, its moisture levels, and how much sun that particular area of your lawn is getting.
Consider Your Grass Type
Finally, consider if the grass type you’re using on your lawn is suited to the lawn you have. You may want to use a type of grass that is more suited to your area’s climate, the type of soil you’re using, or the level of direct sunlight on your lawn.
Summary
There are plenty of different types of lawn fungus out there, none of which you want to have. If your lawn does become affected by a lawn fungus, then correctly identifying the type of fungus present is the most important step when it comes to figuring out how you’re going to treat it and prevent it in the future.
Hopefully, with the information we’ve shared with you today, you should find it a lot easier to identify and deal with whatever type of fungus happens to be affecting your lawn!