White cotton like fungus on lawn

Powdery Mildew On Grass: How To Control Powdery Mildew In Lawns

Powdery mildew disease in lawns is usually the result of trying to grow grass in a poor location. Caused by a fungus, the first symptoms are light spots on the blades of grass that may go unnoticed. As the disease progresses, you’ll see white patches that look as though they have been sprinkled with talcum powder. Let’s take a closer look at powdery mildew grass disease and how to control powdery mildew in lawns.

Treating Powdery Mildew on Grass

When your grass has white powder, fungicides for powdery mildew treatment do a good job of temporarily eliminating the symptoms, but the disease returns if the growing conditions don’t improve. Grass is a sun-loving plant that grows best in open locations with good air circulation and plenty of light.

Powdery mildew grass disease takes hold in shady locations with little air movement. Watering late in the evening, so that the grass doesn’t have time to dry before nightfall, further encourages this disease.

Control powdery mildew in lawns by opening up the area to better air movement and more sunlight. To reduce shade, prune or remove trees and shrubs that shade the grass. If this isn’t possible, consider the advantages of covering the area with attractive mulch instead of struggling to grow grass in a difficult area. The area under a tree is perfect for a mulch-covered shady retreat with garden seating and potted shade plants.

Tips to Control Powdery Mildew in Lawns

You can discourage powdery mildew on grass with a few cultural practices aimed at keeping the grass healthy in shady areas, but these methods are only effective in light or partial shade.

  • Reduce the amount of nitrogen fertilizer that you use in shady areas. Grass grown in shade doesn’t use as much nitrogen as grass grown in sun.
  • Water shaded grass infrequently, but deeply. The soil should absorb the water to a depth of 6 to 8 inches.
  • Water the lawn early in the day so that the grass has time to dry completely before nightfall.
  • Allow the grass in shady areas to grow a little taller than the rest of the lawn. Wait until the blades are about 3 inches tall before mowing.
  • Over seed the existing grass with a shade grass mixture.

Take steps to treat powdery mildew as soon as you discover that your grass has white powder symptoms. If this powdery mildew grass disease is allowed to progress too long, it can spread and result in dead patches in the lawn.

What is powdery mildew?

This lawn disease is a parasitic form of a plant life called fungi. Fungi live in the soil, thatch and dead leaves all year round and feed by drawing nutrients from the grass.

Powdery Mildew is a damaging disease of bluegrasses and fescues. Periods of low light intensity and poor air circulation favour the disease. Heavily shaded areas are particularly susceptible. The disease is most severe during the spring and fall at temperatures between 15-22ºC. However, under the right conditions it can occur at temperatures ranging from 1-30ºC.

How can I tell if I have powdery mildew in my lawn?

The symptoms of powdery mildew include the following:

  • Early stages of Powdery Mildew are recognized as isolated colonies of whitish fungal structures called mycelia appearing on the leaf blades

  • The mycelia colonize and infect a large portion of the leaf blade with a whitish, grey dusty powder

  • Older leaves are more severely infected than younger leaves

  • Heavily infected leaves can turn yellow then brown and die. Colonies of powdery mildew darken with age

  • Infected plants are weakened becoming more susceptible to other stresses

If you are not sure if you have Powdery Mildew, call your local Weed Man Professional for a free healthy lawn analysis. They will diagnose the problem and advise on the proper corrective measures.

How can powdery mildew be treated?

The best treatment for Powdery Mildew is to alter some cultural practices that are causing favourable conditions for this disease to spread. As long as conditions remain favourable Powdery Mildew will continue to infect the grass blades and over extended periods of time will start to cause permanent damage. These cultural practices include;

  • Increase air circulation and light penetration through pruning and thinning trees and shrubs

  • Over seed lawn areas with a shade tolerant grass seed

  • Raise mowing height making sure it is being cut at 6 to 8 cm

  • Water deeply and infrequently to avoid drought stress

  • Improve drainage to increase water absorption to the root zone and increase air circulation. Lawn core aeration will assist in accomplishing this

  • Do not water at night. Water laying on grass plants overnight encourages the disease to spread

  • Provide adequate fertility while avoiding excessive nitrogen that can contribute to the disease. A slow release granular fertilizer like Weed Man’s exclusive blend will provide nitrogen over an extended period of time

If you have any further questions about Powdery Mildew in your lawn or have any other questions or concerns, please feel free to contact your local Weed Man Professional.

Powdery mildew happens to even the most carefully tended plants – seemingly out of nowhere, prized ornamental plants and lawns get a fuzzy gray coating that reminds you of that container you pulled out of the back of the fridge. Powdery mildew isn’t immediately fatal, but it can cause considerable stress to your plants. Fortunately, you can control it in a few easy steps, and here’s how.

About Powdery Mildew

The term “powdery mildew” actually refers to an entire group of fungi, each one attacking different types of plants. It usually starts with a few round white or grayish spots that you can rub off with your finger. They spread and join until the entire top leaf surface is covered, then it moves on to the underneath, stems, flowers, and fruit.

As powdery mildew takes over, photosynthesis becomes very difficult for the plant. This can cause growth of the plant to slow and distort, leaves to fall, and flowers and fruits to fail to form properly.

Powdery mildew can affect any plant, but lilacs, roses, fruit trees, vegetables, begonias, and lawns are particularly susceptible. Since the fungi are species specific, powdery mildew on your fruit trees won’t spread to camellias or other plants.

Conditions Favorable for Powdery Mildew Growth

Powdery mildew thrives in dry weather with high relative humidity. Unlike other fungi, it doesn’t like rain or extreme heat, and it tends to slow when temperatures soar over 90° F. Powdery mildew needs a dry leaf surface, moderate temperature, and high humidity to form. These conditions are often caused by:

  • Seasonal weather: A summer that combines drought with high humidity is an invitation to powdery mildew.
  • Crowded plants: Densely packed plants, overgrown shrubs, or plants under trees, are more susceptible to powdery mildew due to poor air circulation and cool, humid conditions.
  • Overfeeding: Lush, succulent growth caused by over fertilizing is particularly susceptible to powdery mildew.

How to Treat Powdery Mildew

Powdery mildew may seem to spring up faster than you can control it, but the good news is that it’s easy to treat and not immediately fatal. Take these steps to treat powdery mildew on your plants:

  • Prune: Cut off affected growth, prune the plant to open it up to more air circulation, and trim back tree limbs that might be shading too densely.
  • Disinfect: Clean pruning tools in a bleach/water solution to kill any remaining spores.
  • Clean Up: Pick up all fallen leaves and pruning debris and put either in the trash or in a hot compost pile.
  • Stop Fertilizing: Reduce nitrogen fertilizer in order to slow down succulent growth.
  • Spray with Water: If plants are in the sun, try washing the patches off the leaves with a spray of water. Avoid extra water in shady or damp areas.
  • Spray with Fungicide: If all else fails, spray plants with an eradicating fungicide. Check the label to make sure it’s rated both for powdery mildew and for your plant type. Natural treatments include neem oil, copper, and potassium bicarbonate. Use chemical fungicides only as a last resort.

How to Prevent Powdery Mildew

Of course, the best way to treat any plant disease is to avoid it in the first place! Try these steps to keep powdery mildew from taking over your yard:

  • Choose Resistant Plants: Some varieties of plants are more resistant than others – check the plant labels before you buy.
  • Focus on Air Flow: When planning your garden, make sure that all areas have adequate air circulation and that plants are adequately spaced. Thin or prune plants and trees as necessary to prevent stagnant, humid corners.
  • Grow in Sun: Whenever possible, orient your planting beds so they get at least a few hours of sun each day.
  • Use Preventative: If powdery mildew is a problem in your yard, spray your plants with preventative fungicides to keep it at bay. Natural preventatives include sulfur and baking soda. For an easy homemade preventative spray, mix a spoonful of baking soda and a spoonful of either dish soap or horticultural oil (such as neem oil) into a gallon of water. Don’t overuse the spray – you don’t want to the baking soda to build up in your soil.
  • Spray Regularly: Apply preventative sprays every couple of weeks.
  • Vary Plantings: Since the fungus is species specific, reduce infection of your annual plants by rotating the varieties of plants each year.
  • Water Wisely: Water in the morning to allow plants to dry. Use soaker hoses and drip irrigation, rather than overhead sprinklers, to reduce humidity around your plants.
  • Don’t Overfeed: To keep growth in check, use balanced organic fertilizers and compost, rather than high-nitrogen chemical fertilizers.

My Grass Has White Spots

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Grass blades exhibiting white spots indicate a fungal disease called powdery mildew. Powdery mildew is the most widespread disease that infects plants, according to Colorado State University. However, gardeners can have peace of mind knowing that the fungal spores that cause lawn powdery mildew will not infect your other plants.

Powdery Mildew

Powdery mildew typically infects lawns during July through September, according to the University of Rhode Island. Fungal spores quickly germinate in a few hours when temperatures are cool and lawn is moist. Furthermore, powdery mildew fungal spores are almost always present in the lawns, but may not be infecting grass. Spores overwinter in dead grass debris and spread when the weather favors the disease. Because the disease can infect grass in two hours, gardeners can see severe powdery mildew symptoms in a week, reports the University of Rhode Island.


Upon close examination, gardeners can see tiny white spots on their grass. Spots may appear to look like powder. This powder is a combination of mycelium and fungal spores. Mycelium is the branching parts of the fungal spores. The disease sucks up the nutrients from the surface of the grass blades. Grass blades become malnourished and turn yellow from the result of the lack of nutrients. Also, severe powdery mildew infections cause small to large areas of the lawn to die out.

Treating Powdery Mildew in the Shade

Grass growing in the shade is the most susceptible to contracting powdery mildew. Shady environments favor the germination and spread of powdery mildew fungal spores. Gardeners can control powdery mildew by cutting back overhanging branches in these areas. Trees that cast too much shade can be removed. Also, planting grass that tolerates shade will reduce the chances of powdery mildew damaging the lawn. Healthy grass tolerates moderate infections of powdery mildew. Shade tolerant grass types include St. Augustine, zoysia, fescues and supina bluegrass.

Cultural Management Strategies

Avoid overfertilizing your lawn to prevent stressing out the grass. Stressed out grass dies out when infected with powdery mildew. Avoid using more than 1 lb. of slow release fertilizer per 1,000 square feet at one time. Using too much nitrogen can burn grass and weaken grass blades. Furthermore, reduce your irrigation if you give your lawn more than 1 inch of water a week. Typically, lawns only need more than one inch of water each week to keep them from drying out.

How do I fix dead white patches in my lawn?

So no presents for you under the plastic then! I’m glad really – that larvae you found could be the larvae of a moth or butterfly because its not immediately recognisable as a leatherjacket, but might have been. What’s odd is you found it actually under the lawn, and that isn’t at all typical of moth larvae.

First, I’d note that your lawn is cut way too short – I know you said you had the mower on the highest setting, but perhaps there’s something wrong with your mower, because, for this time of year, it is too short. I do see lots of what could be dandelions – inspect the lawn thoroughly and decide whether the ratio of weeds and moss to turf is greater than the amount of grass. If it is, you might want to consider stripping it out, including weed roots, preparing the area and laying new turf.

Otherwise, I don’t know what kind of regular maintenance routine you’ve carried out over the previous years, but now is the time to apply a lawn feed, so use a granular preparation with a moss killer, but not a weedkiller – apply at the rates indicated on the box, at least three days after cutting, and try not to overdose. If your soil is heavy, aerate the area by inserting a garden fork about every 9/12 inches, vertically and removing it at the same angle, then feed. Apply when the blades of grass are dry, but on a day when you know rain is due within 1-3 days.

In the meantime, get some Verdone Extra, which is a liquid lawn weedkiller – you’ll need a can to mix it in. As the lawn starts to grow and the weeds are growing strongly, with entire leaves and looking lively and bushy, apply the Verdone according to the instructions on the bottle. The reason I suggest a separate weedkiller is because the standard Lawn Weed Feed and Mosskiller preparations are pretty hopeless at killing weeds in lawns, so although it’s tedious to apply two different products, it will be more effective.

If any moss that’s present turns black, rake it out, and if that leaves bald patches that are quite noticeable, you may need to reseed those patches, but that can’t be attempted until six weeks after the chemical treatments have been applied. At this point, you could scarify the lawn – it will make it look pretty awful, but it should recover quickly.

Ensure the blade/s on your mower are good and sharp; raise the height of cut on your mower so that, after cutting, there’s a good inch to inch and a half of grass growth left behind. Re-apply your lawn feed 6 weeks after the initial application, depending on the instructions on the box you buy, but do not use past July. Any feed after that should be an Autumn one.

If you want more guidance, there’s a book called The Lawn Expert by D. G. Hessayon – you might find the library has a copy, or a charity shop, and last time I looked, there were copies available on Amazon and Ebay. Full retail price around £14, cheaper second hand. Although the chemicals mentioned within it may be out of date, the basic routines outlined in there are entirely valid and haven’t changed – contains information on how to lay a lawn, recognise and treat problems, and maintain an ongoing good lawn, including topdressing.

Example of Brown Patch. Photo by Dr. Van Cline, Agronomist, The Toro Company.

Brown Patch

This disease is prevalent during moist, hot weather on over-fertilized lawns. Brown patch, also known as rhizoctonia blight, is most active when grass remains wet and temperatures reach 80 to 90 degrees Fahrenheit.

Look for:

Dark, water-soaked looking grass turning into browned-out circular areas several inches to several feet in diameter. Some green leaves may persist within the patch, and roots remain intact. In addition, blades may have irregular ash gray lesions with a dark brown margin running along one side. On short turf, a 2-inch “smoke ring” of gray mycelium may encircle the patch in early morning.


Water deeply but infrequently, mow high, remove excess thatch, and improve aeration and drainage.

Example of Dollar Spot. Photo by Dr. Van Cline, Agronomist, The Toro Company

Dollar Spot

This disease affects lawns during heavy dew periods that are low in nitrogen and stressed by drought. Dollar spot, named after the silver-dollar-sized spots that appear on closely mowed lawns, signal nutritionally deficient turfs.

Mottled, straw-colored 4 to 6 inch wide patches on lawns with taller grass. Grass blades have light tan bands with reddish brown margins spanning across them. Patches may merge to form large, irregular areas. Grayish white cobweb-like mycelium may also be present in early morning.

Maintain adequate nitrogen and potassium fertility, water deeply when necessary, and remove excess thatch. If your grass is prone to dollar spot, remove morning dew by dragging a hose across the lawn. Alternatively, over-seed with a blend of improved cultivars.

Fairy Rings

Did you know, people believed fairy rings developed because fairies were dancing in circles on the grass or in the forest? Now we know these rings develop because of older

Example of Fairy Ring
Credit: Iowa State University

mycelium in the center dying and exhausts the soil of nutrients, forcing the living edge to grow outward in a circle.

Patterns of circles and arches made from mushrooms or grass that seems lusher. One type of ring causes grass to wither in the circular pattern.

Purdue University scientists say there is no controlling fairy rings. The only choices are to dig up the area entirely or use lawn treatment so the ring is less visible.

Gray Leaf Spot

Example of Gray Leaf Spot
Credit: University of Minnesota

Gray leaf spot mainly attacks perennial ryegrass and St. Augustine grass. The disease occurs in prolonged hot moist conditions with heavy fertilized grass.

On St. Augustine grass symptoms are round leaf lesions which are olive-green to brown in color. As the lesions grow, they can become oval or elongated with tan centers and dark borders. On perennial ryegrass leaf lesions are oblong shaped with grayish centers and dark borders. The symptoms on large patches look similar to pithium blight, but without the mycelium.


Use practices to decrease soil compaction and thatch, which will allow better drainage.

Example of Powdery Mildew

Credit: Cornell University

Powdery mildew is a fungal disease that affects a wide variety of plants. It grows on places of high humidity with a moderate temperature range. This crop is harmful to plants and if not managed, could reduce crop yields.

Plants displaying white powdery spots on leaves and stems. As the mildew grows, the spots will appear larger and may grow on to the plant’s stem.

Lots of home remedies can be very efficient in curing your plant of powdery mildew. A good recipe is to mix one-gallon hot water, 1 tbs baking soda, and 2 drops liquid soap. This mixture is to be sprayed on the plants every 7-14 days depending on the sensitivity of the leaves. This recipe is successful because it changes the PH balance of the sprayed area and makes it unsuitable for the growth of the spores.

Pythium Blight

Example of Pithium Blight Credit: NC State University

Pythium blight, also known as grease spot or cottony blight, spreads rapidly and causes die-off, often in less than a single day. It is a serious disease involving the entire grass plant and occurs on poorly drained soils that have a wet grass canopy. Look for it when nighttime temperatures (Fahrenheit) plus relative humidity equals 150.

The sudden appearance of 1 to 6-inch wide reddish-brown wilted patches, which turn to streaks as they enlarge along drainage patterns. In early morning, the grass will be slimy, dark, and matted. White cottony mycelium may be present when grass is wet. As it dries, the grass turns light tan and shrivels.

Improve drainage and air circulation, avoid overwatering, aerate, reduce excess thatch, and avoid nitrogen fertilizer during warm weather. Check calcium levels, and add lime if deficient. Observe closely for spread, and consult your Cooperative Extension Service (CSREES) if the disease progresses.

Red Thread

Example of Red Thread
Credit: University of Illinois

Red thread causes red threadlike structures to extend from the top of the grass blades. It occurs in areas with low nitrogen and potassium.

Red threadlike structures which extend from the upper part of the grass blade. Red thread grows in small circular patches and causes blighting on turf.

Fertilizing the lawn with nitrogen and potassium can reduce the infestation of red thread. Cultural practices should be continued to be used such as watering deep and infrequent and mowing the grass at the recommended mowing height.


Rust is a self-limiting disease aptly named for the color your grass turns when it is present. A closer look at grass that has been infected with rust shows orange, red, brown, and yellow spores that rub off when touched. Photo by Dr. Van Cline, Agronomist, The Toro Company

When growth slows during hot, dry weather, rust appears on compacted, shady, or low fertility lawns.

Initial small yellow flecks that develop into pustules releasing yellow, orange, red, or dark brown spores. From a distance, the turf appears orange or yellow, and the colored spore residue will rub off when touched.

Provide appropriate fertilization and irrigation, prune low-hanging tree branches to reduce shade, maintain aeration, mow frequently, and bag clippings. Upgrade your lawn with a rust-resistant cultivar if the disease persists.

Summer Patch

Example of Summer Patch
Credit: Purdue

This disease is caused by a fungus named Magnaporthepoae and infects and destroys grass roots. Grass growing in a sunny, hot lawn is the most common area for summer patch to develop.

Wilted, dark green circular areas that are 1-2″ in diameter. In the second stage, the grass will turn a straw-brown color. The result of this may look like a “frog eye” pattern reaching 2-12″ in diameter.

Management of summer patch is most effective when preventive measures are taken. Certain fungicides can help control the summer patch when applied on 28-day intervals. For a list of recommended fungicides, visit http://www.turffiles.ncsu.edu/diseases/summer_patch.aspx

Common fungi in yards and gardens

Bird’s nest fungi, sphere throwers and shotgun fungi

Bird’s nest fungi (Cyathus striatus)

Bird’s nest fungi (Mycocalia, Nidularia, Nidula, Cyathus, and Crucibulum spp.), sphere throwers (Sphaerobolus spp.), and shotgun fungi (Pilobolus spp.) are three separate groups of fungi with many similarities.

They are all saprophytes, which grow on manure or decaying wood. Since these fungi live only on decaying plant matter, they do not harm living plants.

In the garden, the tiny fungi (under 1/4 inch tall) are usually found on the surface of soil that has been enriched with manure, sawdust or wood chips. They can also be found on old boards used to edge garden beds and on wooden plant labels and stakes.

The fungi are usually spread in manure, but some species may contaminate seed mixes.

All of these fungi can forcibly eject their spores in hard egg-like structures called peridioles. These structures can be ejected 3 feet or more. The sticky spore cases adhere to plant leaves and other surfaces, including home siding and patio furniture.

These fungi are rarely noticed unless they are brought indoors on container-grown plants. The first sign is shiny black or dark brown growths that look like seeds or insects on the leaves. These are the egg-like structures that have been ejected by the fungi. They can be picked off the leaves.

To help control these fungi, remove any fungal fruiting bodies from the surface of the soil. Repot the plant in a potting medium that does not contain manure or wood to prevent the fungi from returning.

Bird’s nest fungi

  • Look like miniature bird’s nests or cups.
  • Shiny peridioles are nestled inside like eggs.
  • Usually only 1/4 inch in height or diameter.
  • Commonly light brown but may be white, gray, yellow or rust colored.
  • The shiny peridioles are generally black or dark brown but may also be white.
  • Immature fruiting bodies look like tiny puffballs, which open into cups as they mature.

The peridioles of bird’s nest fungi are splashed out of the nest by falling water drops. The dimensions and shape of the nest are such that the force of a water drop hitting the bottom of the cup is enough to throw the peridioles over one yard from the nest.

  • When a peridiole hits a solid object such as a leaf or twig, it sticks to the surface in one of two ways. Fungi in the genera Mycocalia, Nidularia and Nidula have sticky peridioles.
  • In the genera Cyathus and Crucibulum, the peridiole is attached to the nest by a coiled cord. When the peridiole is ejected from the nest, the cord separates from the nest, giving the peridiole a four-inch tail. The end of the tail is sticky. When it sticks to a twig or stem, the peridiole swings around its anchor point, wrapping the cord around the stem.

Most bird’s nest fungi in Minnesota belong to Cyathus or Crucibulum.

Sphere throwers (Sphaerobolus spp.)

Cannonball fungus (Sphaerobolus)

  • Grow on rotting wood in many of the same places as bird’s nest fungi.
  • The whitish or yellowish-pink immature fruiting bodies are round balls similar to immature bird’s nest fungi.
  • As the fruiting bodies mature, the outer layer of the ball peels back to form a cup with a single round peridiole inside. This cup is actually two cups, one inside the other, joined at the rim.
  • Pressure builds up between the two cups, eventually causing the inner cup to explosively invert, or turn inside out.
  • The force of the inversion launches the peridiole, which can travel more than five yards before sticking to any surface it impacts.

Shotgun fungi (Pilobolus spp.)

  • Grow mostly on old horse manure.
  • Clear, glasslike fruiting body consists of a slender stalk topped with a swollen bulb.
  • A shiny black peridiole rests on top of the bulb.

Shotgun fungi (Pilobolus crystallinus)

Pilobolus bends toward the light, which ensures the clearest path for the peridiole to travel. The fungus senses the direction of the light with light sensitive pigments at the base of the bulb. As long as these pigments are illuminated, they send a signal to bend. The bending stops when the opaque peridiole is pointing directly at the light source, shading the pigments.

If grown in the dark, the stalks will all point straight up. The swollen bulb is filled with sugar, which absorbs water until the pressure inside the bulb is five times the pressure outside. As the fruiting body matures, the walls weaken under the peridiole. Eventually the pressure causes the bulb to rupture, sending the sticky peridiole flying.

These ballistic fungi, each with its unique method of spore dispersal, can be a fascinating introduction to the world of fungi. A careful search of the damp corners of your garden in the fall will probably reveal numerous bird’s nest fungi, sphere throwers and shotgun fungi.

When your lawn starts to look a little funky in some spots, your first thought might be to crank up the sprinkler system and douse the spot with some fertilizer.

Put down that garden hose. If your lawn starts developing anything abnormal, it could be a sign of a bigger issue.

In the fight to keep your lawn lush and healthy, one of your biggest nemeses is lawn disease. These diseases, typically caused by different species of fungi, can wreak havoc on even the lushest of lawns if you aren’t careful. If you start to notice your lawn is looking patchy or discolored, it may be that you’ve got a lawn fungus on your hands.

What can you do if you start to notice problem spots on your lawn? Here are some of the most common lawn diseases and what you can do to treat them.

Brown patch lawn disease is pretty much exactly what it sounds like. A fungus called Rhizoctonia infects your grass and causes the area to develop a circular spot of brown and dead grass. You may also notice a dark ring around the patch and tan lesions on the individual grass blades.

Brown patch thrives in areas that experience high temperatures and high humidity during the summer months. Poor soil drainage, overwatering and high nitrogen levels in the soil can also be contributing factors to the disease’s severity.

If you’ve determined your lawn has a brown patch problem, your plan of action should be to reduce the severity of the current flare up and work on prevention for next season.

When battling brown patch, continue to mow regularly, as this will promote air movement and allow your lawn to dry better. Avoid adding excess nitrogen to your lawn, and continue with your regular fertilizer schedule, being careful not to over- or under-fertilize.

Fungicides will likely prove to be fairly ineffective against brown patch that has already progressed. Instead, fungicides work best when applied as a preventive in the late spring or early summer with continued application throughout the summer months.

If you notice your lawn has a bunch of irregular, straw-colored patches of wilted grass, summer patch could be the culprit.

Summer patch tends to make an appearance in the mid to late summer months when temperatures climb above 90 degrees. It’s caused by the fungus Magnaporthe poae, which infects the grass’ roots and disrupts its ability to soak up water and nutrients. Summer patch is a highly destructive disease, and you should begin treating and managing it as soon as you notice symptoms.

Hot, humid weather creates favorable conditions for this disease to thrive. Poor air circulation and soil compaction can also contribute to its progression.

Once you’re able to see the symptoms of summer patch, the disease has already progressed, and getting it under control is difficult. To prevent summer patch from becoming an issue and damaging your lawn, apply fungicide in the late spring, when the fungus has begun doing its damage but hasn’t yet shown symptoms.

To manage summer patch, avoid excessive watering. Use a core aerator to reduce compaction and promote air circulation. Apply a fungicide to control the disease.

Dollar Spots

If your lawn is covered in many small, round, silver dollar-sized brown spots, you’re likely dealing with dollar spot fungus.

Dollar spot tends to appear from late spring to late fall, and prefers warmer temperatures and lots of humidity.

Be sure you’re following an appropriate fertilizing schedule for your lawn, as this disease tends to be more prevalent on under-fertilized grass. Excess moisture and mowing too short can also encourage the progression of dollar spot.

To treat dollar spot, continue to follow your fertilizer schedule, as proper fertilization will help your lawn outgrow the disease. Water deeply but infrequently so that water can penetrate to the roots but will be less likely to linger and create moist conditions, which are ideal for fungal development. Aerating your lawn will also help the moisture penetrate while introducing air flow.

Red Thread

If you’ve got red thread, blame Laetisaria fuciformis. Red thread is pretty distinctive and shows up in your yard as tan or reddish spots. Upon closer inspection, you’ll notice pink, thread-like structures growing from the tips of the infected blades of grass.

Red thread can develop within a relatively wide range of temperatures, usually in the spring and fall. It thrives in cool, wet conditions with limited sunlight. It’s more common in areas with a lot of rainfall.

The key to preventing red thread is to ensure you’re adequately fertilizing your lawn, as undernourished grass is more susceptible to infection.

To treat a current infection, keep up with your regular lawn care, and make sure you’re supplementing your soil with the proper amount of nitrogen.

Red thread generally isn’t a big threat to the health of your lawn and is more of a cosmetic concern, so it doesn’t require a large amount of intervention beyond ensuring that you’re properly nourishing your grass and soil and providing your lawn with enough nitrogen. As such, it may take several seasons before you’re able to get your soil balanced enough to prevent red thread from recurring.

If your lawn looks like a baker sprinkled parts of it with some flour, you’re likely dealing with Erysiphe graminis, the fungus behind powdery mildew.

Powdery mildew likes shady areas in cool, humid climates. Because of this, it’s more common in the spring and fall.

Powdery mildew can damage your grass and, if left untreated, can cause thinning in your yard. To manage the disease, do what you can to increase the amount of sunlight the affected areas of your yard get, such as pruning trees and shrubs. If the grass is in a permanently shaded area you may consider removing the grass and putting down mulch instead in that particular area.

Applications of fungicide may help prevent the growth of powdery mildew.

Is your yard looking a little rusty? No, it’s not the same rust that you see on an old car. Rust fungus is an organism that can infect your grass and give it the appearance of rusted metal. If you think your yard has a rust fungus infection, inspect the grass for small, yellow flecks on the individual blades.

As this disease progresses, the small yellow spots will enlarge and release powdery orange spores.

Rust prefers moderately warm temperatures and lots of humidity. Low nitrogen levels in the soil can also be a factor.

Preventative fungicide application can be used to inhibit future growth. To treat the disease, continue to mow regularly (but not too low) and avoid overwatering. Prune nearby landscaping to maximize light exposure and airflow. Consider planting rust-resistant grass seeds.


Your best defense against lawn diseases is a good lawn care plan. How you care for your lawn will depend on the specific type of grass you have growing in your yard and the makeup of its soil. Here are some basics that will help you put your best foot forward in the fight against fungus.

A good first step is knowing what type of grass is in your yard. There are many different varieties throughout the U.S., and knowing which type you’re caring for will help you make the best decisions on how to care for it.

You should also become familiar with your local county extension office, which can help you when you have any questions about gardening, agriculture and pest control. They’ll give you useful information specific to your location. They can also test samples of your soil and give you recommendations on what types of treatments you should be applying to it.

Once you know what type of grass you have and what the growing environment in your area is like, you’ll be able to create an appropriate fertilizer schedule and know what length to cut your grass.

Water your lawn early in the day so it has time to dry with the help of the sun. Once it gets dark, water won’t evaporate as well and will remain in the soil, encouraging infection.

Remember, fungicides work best as a preventative. If you’re currently having problems with lawn disease, make a note of that for next year, and start applying a fungicide in the spring, so problems can’t recur.

Do you have any tips to keep your lawn fungus-free? Share them in the comments!

If you just aren’t sure what turf problem is causing damage, you can send a sample of the affected grass to your local cooperative. Texas residents can mail impacted turf to the Texas A&M AgriLife Extension’s Texas Plant Disease Diagnostic Lab along with this form. The cost to diagnose your lawn disease is $35 per specimen.

Brown Patch/Large Patch

Brown patch can attack the roots of your grass, so at first the impact can appear to be similar to root rot. The way you can tell you have brown patch is that you’ll also see the blades of your grass turn brown, with small circular tan and brown spots appearing on the blades. As we mentioned earlier, brown patch can be the culprit if you notice that you can easily remove grass blades from the ground, since the fungus rots the plant stems. You may also notice that the stems are be slimy or dark at the base because of rot associated with large patch.

The best way to identify brown patch is if you see yellow circular patches in your lawn. You may see new growth around the center of the circle. Since this type of fungus prefers warm weather, you are more likely to notice this condition between spring and summer. In some parts of the country, hot and humid conditions continue throughout fall and winter months, so you can see brown patch virtually year-round.

Take-all Root Rot/Take-all Patch

The second-most common type of lawn fungus can be called several different names. You can usually tell if your yard is suffering because you’ll notice yellow grass with darker than normal roots. Eventually, take-all patch causes your grass to become thinner. Because this condition impacts a grass’s root system, over time your grass will become easy to pull up if you have take-all root rot.

Take-all patch typically strikes from fall to spring. Unlike brown patch, take-all root rot prefers cooler temperatures. The fungus can be so severe that all of your grass can be impacted—hence, the name.

Take-all is a yard fungus that lives in your soil and dead or decaying plant matter. This condition spreads through a root system and can move to new areas when infected soil, grass and other plant materials are transferred to a new location. In rare cases, take-all patch can be transmitted by mowing or walking through an infected area, usually under wet conditions.

What Else Might Be Wrong With My Grass?

There are several other reasons your grass might be dying or yellow. A pest infestation, underwatering, iron chlorosis and too much shade also cause your yard to die.

When it comes to lawn pests, chinch bugs are the most common culprit to eat away at your grass. These insects typically start near concrete areas such as driveways, sidewalks or curbs. To test for chinch bugs, cut the hole out of the bottom of a metal can (such as a soup or vegetable can). Push the can into the yard about one inch deep near the dead patch. Fill the can with water. If you have chinch bugs, these pesky pests will float to the top of the water.

Grubs can also damage your lawn by feeding on the roots. These creatures can cause damage to your grass—especially after you resod—which can result in your being able to lift turf like a carpet, especially if you have St. Augustine. To determine if you have a grub problem, cut a one-foot square piece of sod in your yard where you believe you have a problem. Lift the section up and visibly inspect it to see if you see the grubs in the soil.

If your grass needs more water, the blades will typically curl in. When you walk across a lawn that is water-deficient, you will be typically be able to see your footprints. To avoid lawn damage from insufficient water, try to water deeply and less frequently instead of watering every day.

If your grass has yellow stripes or is completely yellow, you may have iron chlorosis. This condition occurs when you have too much phosphorus in your soil.

If you have bare patches in shady areas of your yard, you may just have too much shade for your type of grass. Bermuda and buffalo grasses need sunlight and do not grow well in shade. St. Augustine, on the other hand, is shade tolerant, so this variety tends to do better in areas which don’t receive much sun. If St. Augustine isn’t growing in a shady area of your yard, you may need to experiment. Consider adding shade tolerant ground covers, thinning out some tree branches, planting a shade tolerant garden or adding in a water feature and some rocks. If grass just won’t grow in a particular part of your yard, you have many other options, including adding hardscaping, a patio set or even adding in plants in containers.

Lawn Fungus Treatment and Prevention

There are several things homeowners can do to help treat the fungus and to prevent lawn disease. You might consider taking some of the following steps:

  • If you have grass clippings, fall leaves or other debris sitting in your yard, make sure to remove them so that your yard isn’t vulnerable to fungal growth. When you mow, bag your clippings so that you don’t spread possibly diseased grass all over your yard.
  • Lawns with high nitrogen levels promote fungus growth, so test your lawn’s pH before adding fertilizer and add any amendments judiciously.
  • Water deep (four to six inches) and infrequently in the mornings so that the grass and soil have time to dry.
  • Aerate your yard annually.
  • When mowing, don’t take more than ⅓ inch off at each time. Raise the mowing height to allow more surface area for your grass blades to take in sunlight.
  • Fungicides will help treat the diseased grass, while pesticides can help get rid of insects that are destroying your yard.
  • Avoid urea-based fungicides when treating take-all patch and take-all root rot.
  • If you have take-all root rot, lowering the pH levels in your yard can sometimes help.
  • Avoid walking through or mowing the diseased area when conditions are wet because there is a greater change you will accidentally spread the fungus to unaffected areas.

The best treatment for lawn diseases is a combination of turfgrass management and application of the right fungicide at the right times.

ABC Can Keep Your Yard Healthy

Yard fungus is unsightly and hard to diagnose and treat on your own. The professionals at ABC Home & Commercial Services can help you determine what is affecting your yard and the best methods to treat any kind of condition so you not only protect your beautiful lawn from dying but also protect your investment of time and money. We’ll cut out the guesswork for you so you can focus on enjoying your outdoor spaces.

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