Treating Lawn Diseases: Learn About Lawn Disease Control

Treating Lawn Diseases: Learn About Lawn Disease Control

By: Jackie Carroll

While we all dream of having a lush, green lawn this isn’t always the case. Keep reading to learn more about treating lawn diseases.

Controlling Lawn Problems

Most common grass diseases are caused by fungi. Although many of the different types of diseases look similar, the basic control measures are the same:

  • Prevent the disease from spreading by keeping the grass in the affected area short.
  • Remove the clippings, but don’t rake them across the lawn where they can infect other areas.
  • Clean lawn care equipment before moving onto other parts of the lawn.

The steps outlined below helps build a strong lawn that resists most types of turf diseases:

  • Choose a turf grass recommended for your area and always choose the most disease-resistant variety.
  • Level the lawn to get rid of low areas where water might stand.
  • Test the soil every five years and follow the test recommendations.
  • Follow a regular fertilization schedule when fertilizing grass.
  • Keep your mower blades sharp and remove no more than one-third of the blade length every time you mow. Don’t mow wet grass.
  • Aerate your lawn every other year so that oxygen and nutrients can reach the turf grass roots.
  • Remove thatch when it becomes more than 1/2 inch (13 mm.) thick.
  • Keep the lawn free of leaves and debris.
  • Water grass deeply but infrequently to encourage deep roots. Watering early in the morning allows the water to evaporate during the day. Wet grass overnight encourages disease.
  • Watch for problems so you can head them off before they become serious.

Lawn disease control is challenging, but good lawn care practices go a long way toward preventing them from taking hold in the lawn. These lawn care steps can help you stop lawn diseases before they become a problem.

Identifying Common Lawn Diseases

Controlling lawn problems is easier if you can identify the specific disease, but identification can be difficult because so many diseases look alike. To make matters more confusing, lawn diseases resemble other problems such as dog urine spots, over or under fertilization, over or under watering, too much shade, and dull mower blades.

Large brown spots in the lawn can indicate brown patch disease or anthracnose. Brown patch spots are usually circular, while anthracnose spots are irregular.

Spots about the size of a silver dollar indicate dollar spot. Bluegrass develops spots caused by Fusarium blight during hot, dry weather. Cool-season grass can develop Fusarium patch or snow mold after cool weather or snow melt. It can be gray or pink, depending on the type.

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Lawn Problems: Common Lawn Pests and Diseases

There probably isn’t a lawn in the world that isn’t home to a population of insects, bugs and a host of other pests. While a healthy lawn will be reasonably resistant to pests and to the many diseases that can damage grass, no lawn can ever be totally safeguarded against every possible problem.

The first rule in terms of both pests and plant diseases is to identify them early on and to take immediate action. This means that you need to know what the possibilities are and how what can be done to solve the various problems. That is the only way you can eradicate the problems before any serious damage is done.

Common lawn pests

Common lawn pests come in all shapes and sizes. The damage they do will depend on the pest. Although many people consider moles to be a lawn pest, these creatures don’t actually eat the grass or the grass roots, but they do make numerous tunnels that can cause the lawn to collapse. These tunnels are also used by other pests that do eat and otherwise destroy the grass.

In basic terms there are pests that live in the soil under the lawn, and those that live in the thatch. Those in the soil tend to cause grass to die, although you may be able to save it if you pick up the problem when the grass is still just wilting. Thatch inhabitants do sometimes cause the if you pay attention, you can see how the grass is being nibbled away.

These are some common lawn pests:

  • Various crickets feed on grass and tunnel through lawn, throwing up small mounds of earth. Light brown mole crickets lay their eggs underground in spring. They live deep in the ground for most of their short lives, often feeding on the grass just under the surface of the soil. If left unchallenged, mole crickets will eventually completely destroy the grass and leave only bare ground.
  • Greenish-brown to fleshy white lawn caterpillars attack the grass just above the thatch layer, which results in yellow or brown patches on the lawn.
  • Fleshy white, C-shaped white grubs have three pairs of legs, a bluish abdomen and a distinctive brown head. The larvae of scarab beetles (sometimes called chafers), these grubs live in both the soil and thatch just below the surface of the lawn feeding on humus and grass roots. These grubs live for anything from several months to three years and they destroy the grass roots, leaving the blades to wither and die.
  • Spittlebugs are less than ½ inch long and they have distinctive orange stripes across their wings. They lay orange-colored eggs in hollow stems and in the thatch, and when the nymphs hatch, they start sucking the juice out of the grass. Then they cover themselves with a mass of frothy spittle – hence their name. When lawn is heavily infested with these bugs the lawn will feel squishy underfoot. They are attracted to centipede grass that is growing in shade.
  • Chinch bugs are a lot smaller than spittlebugs and they infest a variety of grass they turn red. They also suck out the juices from the grass, but what they do is to release toxins that kill the grass. Chinch bugs love sunshine and they usually feed out in the open. This makes them difficult to control.
  • Plump, grey, greasy cutworms grow up to about 2 inches in length. They live just below the surface of the ground, feeding at night by literally cutting off the blades or stems.
  • Harvester termites build subterranean nests that can be identified by holes on the lawn’s surface, surrounded by small mounds of soil. They emerge from the holes at night or on cool winter days. These termites get their name from the fact that they cut off bits of grass and carry it away to their nests.

Common lawn diseases

Undernourished lawns are most likely to be attacked by disease. While there are some species that have better disease resistance to other species, a well-cared for lawn of any type will generally be resistant to attack. The other factor to remember is that different grasses are better suited to certain climatic conditions. Planting a species that isn’t really suitable is asking for trouble. Also, if the conditions for that particular grass are too moist then it will be susceptible to various types of fungal attack.

These are just a few of the common diseases that lawns suffer from:

  • Dollar spot which leaves small, round areas of dead grass from 1 to 5 ins in diameter. Leaves seem to be wet and you can see fine, white fungal threads on them in the early morning.
  • Fairy ring which results in darker green grass that spreads outwards in ever-increasing circles. It is caused by various mushroom-forming fungi, most of which are poisonous.
  • Leaf spot which occurs on the blades, sheaths and stems of grass in the form of purple or brown spots. It weakens grass and can kill it.
  • Leaf blotch attacks blades and sheath and looks like tiny purple-red spots. Seedlings are very susceptible, and if attacked usually wilt, turn brown and die.
  • Powdery mildew which results in a grey-white powder forming on the blades. It usually starts in small, isolated patches and then spreads over much larger areas. When it gets really bad, the blades of the grass turn yellow.
  • Rust starts in the form of tiny yellow spots on leaves and the grass stems that then form rusty pustules. It kills the blades of grass and threatens the lawn as a whole.

Environmentally friendly treatment tips

If you have problems with insect pests or diseases you need to evaluate exactly what the problem is so that you can treat it correctly.

Before you resort to herbicides and toxic pesticides, try a more environmentally friendly treatment. Here are some helpful tips:

  • Mix 2 oz. of dishwashing liquid with a gallon of water and sprinkle over the surface of lawn you suspect has become infested with worms and bugs. Within 10 minutes they should come to the surface and you can remove them.
  • Pour soapy water into holes made by crickets. This will usually force them out of the burrow and you can remove them by hand and get rid of them.
  • Mole crickets have become resistant to many of the pesticides on the market (all of which are in any case toxic). But Jeyes Fluid, formulated for neutralizing odors, killing bacteria, and general disinfecting, can effectively control crickets if poured down the burrows.
  • The best way to get rid of moles is to invade their tunnels. There are several ways to do this, from flooding them with water to bombarding them with moth balls. If you can bear the idea, you can also push dog pooh into the tunnels. This does work!
  • Grass usually becomes diseased when it is undernourished. So fertilize regularly using a good, well-balanced product that contains nitrogen, phosphorus and potassium, as well as trace elements and other nutrients.
  • Most diseases that affect grasses can be beaten by generally improving growing conditions.
  • Correct fertilization and watering as well as top dressing help to manage dollar spot.

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Top 5 Common Lawn Diseases To Watch For

Q: What are the turfgrass diseases that I should watch out for most on my clients’ lawns?

A: Managing turfgrass can be tricky, so here are the top five lawn diseases not to be ignored.

1. Brown patch (Rhizoctonia solani)

One of the most widely spread diseases that can affect almost any cool-season turf lawn in many parts of the country is brown patch. When nighttime temperatures start hovering around 65 to 70 F in early summer, this disease can wreak havoc on tall fescue, Kentucky bluegrass and perennial ryegrass. While it is relatively easy to identify (see brown patch symptom photo above), it can sneak into any turf stand and by the time you notice, it will be at significantly high levels. Fortunately, the solutions to control brown patch are numerous and effective. The QoI family of fungicides (strobilurins) are among the best fungicide options for control of brown patch because they offer up to 28 days of control, as well as control of other diseases that may occur at the same time.

2. Large patch (Rhizoctonia solani)

A pathogen similar to the one causing brown patch causes large patch on warm-season turfgrasses such as zoysiagrass and bermudagrass in the transition zone and South. While the pathogen may be the same, the symptoms of large patch are quite different from brown patch, in that they typically occur in spring or autumn especially under overcast, cool and moist weather conditions. As its name implies, large patch symptoms generally begin as small baseball-sized patches but can develop into automobile-sized areas. When the disease is active, off-colored turf around the edges of the patch can be observed with very thin existing turf or other healthy species that are not affected by the disease in the center of the patch. Control with fungicides is effective with applications the previous fall or in the spring at first sight of the disease. Multiple spring applications may be necessary to arrest disease development. Strobilurins, SDHIs (penthiopyrad, etc.) and combination products containing strobilurins and DMIs (azoxystrobin + propiconazole) are effective options for control.

3. Pythium blight (Pythium aphanidermatum)

Pythium blight is a foliar disease that can occur quickly in susceptible stands of turf, especially seedlings. Classified as a water mold, pythium outbreaks are generally associated with poorly drained soils or damp, humid conditions in the turfgrass canopy with little drying of the turf leaves. Newly seeded areas receiving daily irrigation can provide ideal environments for pythium development. Pythium blight symptoms include circular areas 1 to 3 inches in diameter and foliage can have a gray, water-soaked appearance and possibly white mycelium on mornings with dew. Fungicides are available for control of pythium (mefenoxam, etc.), but they need to be applied prior to observing symptoms. Once symptoms appear, fungicides are not nearly as effective in arresting the disease.

4. Pink snow mold (Microdochium nivale)

With a name like pink snow mold, one might think this disease would be easy to identify. However, pink snow mold is only pink for a short period of time and does not need snow to infect turf. In areas where cool, humid weather persists, the Pacific Northwest for example, pink snow mold can occur year round. Initial symptoms include small circular patches that may include a water-soaked appearance around the edge. Under very wet conditions, white mycelium may be visible in the patch and the margins may be reddish pink. The patches become tan and bleached of color under dry conditions. While there are options for controlling pink snow mold once the symptoms are visible, preventive applications are much more effective at keeping the disease at bay. DMI and strobilurin fungicides are the most effective and have the longest residual of control. Multiple applications may be needed as conducive conditions persist.

5. Summer patch (Magnaporthe poae) or necrotic ring spot (Ophiosphaerella korrae)

While arguably not as prolific as some of the other diseases listed so far, summer patch and necrotic ring spot in Kentucky bluegrass can be one of the more difficult diseases to manage. Symptoms generally are expressed as circular patches of tan or brownish turf late in the summer. This particular disease does its damage in the late spring to early summer but symptoms are not expressed until the turf is under stress later in the summer. Once symptoms show up, control options are quite limited. Fortunately, preventive fungicide options are available to suppress, if not eliminate, summer patch and necrotic ring spot damage on turf. These applications should be timed in the late spring when the pathogen is active, targeting applications when soil temperatures reach 65 F. Strobilurins and DMI (propiconazole) fungicides are most effective. Once disease symptoms are visible, frequent irrigation to help the turf recover is helpful, but chemical control options are ineffective at this stage.


How to Deal with Grass Fungal Diseases in Your Lawn

Irregular patches of fungal disease in centipede grass lawn.

Lawn fungal diseases take on a variety of forms – from dead-looking brown patches to highly visible spots, threads, rings, or slimes. And once they strike your yard, grass fungal diseases can be difficult to treat.

Fortunately, the right lawn care practices can go a long way toward prevention and treatment and in severe cases, a fungicide can help eradicate the spores to keep it from spreading. Here are some tips for preventing and treating fungal diseases in your lawn.

Mowing your grass too low can encourage fungal disease.

Causes of Lawn Fungal Disease

Your lawn is naturally full of fungi and spores, some harmless and some problematic, but the right (or wrong) conditions can cause grass fungus to erupt into a harmful disease. The most common causes of a lawn fungal disease are:

  • Drought
  • Improper mowing (especially mowing too low)
  • Compacted soil
  • Overwatering
  • Too much fertilizer (or using the wrong kind)
  • Wrong grass type for your yard
  • Weather conditions (particularly temperature and humidity)

How To Identify Lawn Fungal Diseases

Signs that your lawn may have a fungal disease include:

Brown patch of dead grass in lawn.

  • White, yellow, or brown patches or rings that grow in diameter.
  • Thin patches of frayed, distorted, or discolored grass blades.
  • Gray, black, red, orange, or purple spots on blades or stems.
  • Gray, black, or pink powdery or threadlike coatings on and around grass blades.
  • Areas of darkened, wet-looking, slimy, or greasy-looking grass.

Common Lawn Fungal Diseases

There are quite a few fungal diseases that can impact lawns, but they’re usually pretty specialized, targeting specific lawn types, at certain times of year, under certain conditions. For example:

  • Brown patch strikes during hot, humid weather.
  • Fusarium blight prefers hot, drought conditions.
  • Dollar spot tends to spring up when nights are cool and dew is heavy.

Before treating your lawn, it’s important to identify not only whether your lawn indeed has a fungal disease, but to identify the fungus itself. All fungicides aren’t the same, and some diseases can be easily treated by making changes in your lawn care.

Knowing your grass type and recent weather conditions can make it easier to narrow down, but you may need help in figuring out exactly what’s going on. Your local cooperative extension center is your best resource for determining which diseases are most common in your area, or you can take a small baggie of the infected grass to your local garden center for help.

Applying an antifungal treatment may be necessary to treat severe cases.

How To Prevent and Treat Lawn Fungal Diseases

A simple change in your lawn care practices may be enough to prevent or eradicate lawn fungal disease. At other times nature may deliver a soggy spring or summer heat wave that just can’t be helped. Stressed or unhealthy lawns are much more likely to develop disease so the better you care for your lawn, the better the grass will be able to handle the natural conditions in your area.

Follow these steps to help take control of fungal diseases in your lawn:

  • Soil Test: Conducting a soil test can not only identify nutrient deficiencies that lead to stressed lawns and disease but sometimes can be used to diagnose the disease itself. Check with your local cooperative extension office for more information.
  • Aerate: Loosen soil by aerating your lawn every year or two.
  • Top-Dress: Apply and rake in a layer of rich, organic top-dressing to improve the soil, increase drainage, and help combat disease.
  • Dethatch: Remove thick buildups of thatch in your lawn to allow the soil to breathe. Improper watering can lead to lawn fungus.
  • Grass Type: Rather than fighting nature to have an exotic lawn, choose a grass type that’s suited for your climate, soil, and light conditions. Well chosen lawns are stronger and able to fight off the normal fungal spores native to the area.
  • Go Organic: Synthetic fertilizers, pesticides, and other lawn chemicals can upset your lawn’s ecosystem – allowing disease organisms to grow unchecked. Using organic materials helps keep your lawn in balance.
  • Fertilizing: Both over and under fertilizing can promote some fungal diseases. Choose organic, slow-release fertilizers for your lawn, and apply them exactly as instructed. Avoid excess nitrogen, which creates a fast green lawn with very poor defenses.
  • Watering: Water early in the morning, to allow the grass blades to dry during the day. Give your lawn one inch of water per week, and use a rain gauge to keep track. Water deeply, but less frequently, to encourage stronger roots and to allow the water to absorb properly.
  • Mowing: Follow good mowing practices, including keeping the mower blades sharp and mowing your lawn to the correct height. Scalped lawns are much more vulnerable to fungal disease. If your lawn has diseased patches, be sure to wash and disinfect the underside of your mower after each use. Antifungal grass treatment for lawn.
  • Air Circulation: Many lawn fungi develop under moist, still conditions. Thin out trees and shrubs to allow air to circulate all over your lawn, and plant shade-tolerant grasses under trees.
  • Snow: Avoid walking on or compacting snow in your yard during the winter, since heavy snow layers can breed snow molds that emerge in spring.
  • Go Natural: If certain areas of your lawn are prone to fungal disease due to conditions you can’t change, consider naturalizing the area with groundcovers or flower beds that will be better suited to those conditions.
  • Organic Treatment: Applying organic treatments – such as neem oil, compost tea, or a weak baking soda solution – can help with small patches of fungus.
  • Fungicides: If all else fails, look for a fungicide (preferably organic) that’s rated specifically for your lawn disease. Fungicides won’t help your grass regrow, but they’ll get the fungal spores in check so that your improved lawn care practices can take effect.


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Weeds aren’t the only thing standing between you and the lush lawn of your dreams. Once your turf is established, you’ve got to watch for pests, fungal diseases—and even Fido. Got a mysterious brown spot or dry patch plaguing your grass?

Don't worry about it. You can make your yard beautiful again. Here are 8 common problems, along with symptoms and remedies for each one.

Problem: White Grubs

Photo by Courtesy Missouri Botanical Garden PlantFinder

Symptoms: Irregular dead spots caused by beetle larvae feeding on grass roots. Damage is worst in the fall. Dead turf pulls up easily, like a rug, revealing c-shaped larvae. Animals such as armadillos, skunks, and gophers dig up lawn to feed on grubs.

Solution: Imidacloprid applied in late spring to early summer is the most effective chemical control. Predatory nematodes are a useful organic control.

Problem: Chinch Bugs

Symptoms: Irregular dry spots that turn yellow, then brown, as if drought-stressed. Caused by a tiny insect that sucks juices from grass blades. Chinch bugs usually infest St. Augustine lawns.

Solution: Better care and aerating usually helps. 'Floratam' is a resistant variety of St. Augustine. Treat with an appropriately labeled insecticide.

Problem: Sod Webworm

Symptoms: Irregular dead spots caused by small gray or tan caterpillars feeding on grass blades. You may also see zigzagging moths at night. Confirm the presence of webworms by soaking a small area with soapy water (two tablespoons of dish soap in a gallon of water). They'll come to the surface in about 10 minutes.

Solution: Aerate to reduce thatch. Treat with appropriately labeled insecticide. Bacillus thuringiensis (Bt) is an effective organic control.

Problem: Dog Damage

Photo by Micah Young/ istockphoto.com

Symptoms: Small dead spot usually surrounded by lush, dark green grass. Caused by dogs making a pit stop.

Solutions: Simple but difficult—keep the dogs away. The dead spot will usually recover, especially if you soak it with a hose.

Problem: Fungus Disease

Photo by Courtesy Missouri Botanical Garden PlantFinder

Symptoms: Quickly appearing and expanding dead spots caused by a number of difficult-to-diagnose lawn diseases.

Solution: Most lawn diseases can be cured by adjusting cultural practices, such as watering or fertilizing less or watering or fertilizing at different times. Aerating also helps. Get help properly identifying the disease from a local nurseryman or cooperative extension service before using fungicide.

Problem: Striped Lawn

Photo by BanksPhotos/ istockphoto.com

Symptoms: Healthy, green turf alternating with yellow stripes. Caused by uneven fertilizer application.

Solution: Make sure you overlap wheel tracks when applying fertilizer with a drop-type spreader. If stripes are more tan or brown than yellow, your lawn mower may need to be adjusted to cut more evenly and prevent scalping.

Problem: Brown Areas or Dry Spots

Photo by Jacques Arpin/ istockphoto.com

Symptoms: One part of the lawn dries out before other areas. Caused by compacted soil, often due to foot traffic, or improperly adjusted, clogged, or broken sprinklers.

Solution: Annual aerating will improve water penetration in compacted soils. Watch sprinklers run to make sure they operate properly. Adjust or repair as necessary.

Problem: Thin Grass and Moss Growing in Shade

Symptoms: Grass grows poorly in shady areas. Moss fills in just fine.

Solution: Check the pH of the soil. If it's okay, increase sunlight by pruning trees. Reduce watering and aerate. Switch to a more shade-tolerant grass, such as fine fescue, or remove the grass and replace with a shade-tolerant ground cover, such as pachysandra or vinca.


Watch the video: How to Get Rid of Lawn Disease. Fungus Among Us