Red fungus in grass

The Colorful Cool Season Culprit

Red thread (also known as pink patch) is one of the easiest lawn diseases to spot because it sports a distinctive pinkish red coloration. Especially serious in the Pacific Northwest, red thread also appears in stands of cool season grasses over a wide region when weather conditions are right.

When Green Lawns Turn ‘Red’

Red thread lawn disease grows most aggressively when temperatures are in the 68 to 75 degree range and during extended periods of wet or very humid weather. Even though this may seem like a narrow “window” or set of circumstances for disease activity, red thread can overtake a turf area fast. Besides temperature, red thread gets a helping hand from certain nutritional imbalances, too. This lawn disease takes off much faster when there’s a lack of nitrogen, for instance. Low levels of calcium (or lime) also affect some grass types.

Damage Symptoms: What Red Thread Looks Like And Does

The symptoms of red thread lawn disease first appear as “water soaked” darkened irregular areas from just a few inches to several feet across. These areas gradually become bleached or tan colored. Healthy plants are usually interspersed with diseased plants, giving the lawn an over-all ragged look.

As the red thread becomes well developed, light pink to red fungus strands (or threads) 1/4” or more in length begin to grow from the tips of the blades and the leaf sheaths — these threads are the reason for the disease’s common name. The wind moves bits of these threads to non-infected plants to spread the disease. The threads can also touch nearby blades to spread the infection. Red thread lawn disease very seldom wipes out an entire stand of turf, and so infected lawns will often have an uneven or patchy appearance.

Cultural Management: You Can’t Change The Weather

Like most grass diseases, red thread is very much weather related. When conditions are right for development, management of red thread is limited to checking and correcting any nutritional deficiencies or direct treatment with a fungicide material.

Lawn treatments with fungicides are usually effective, and one or two maintenance applications in the spring and again in the fall are adequate in most situations for control.

If you have seen signs of red thread on your turf, please contact your neighborhood Spring-Green. We’re always ready to help with managing disease diseases, so you can have the best lawn possible.

Learn more about…
Rust Lawn Disease
Snow Mold
Spring Dead Spot

How to fight red thread lawn disease: Ask an expert

By OSU Extension Service and Master Gardeners

Winter is bearing down fast, but there’s still plenty to do in the garden. What’s up in yours? Got a question? Get answers from Ask an Expert, an online question-and-answer tool from Oregon State University’s Extension Service. OSU Extension faculty and Master Gardeners reply to queries within two business days, usually less. To ask a question, simply go to the OSU Extension website and type in a question and the county where you live. Here are some questions asked by other gardeners. What’s yours?

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Courtesy of OSU Extension Service

What’s this pink visitor in the lawn?

Q: The images included, taken Nov. 28, are from the grass area in the back yard. The grass area is the highest ground in the garden and our lot might be the highest in the block. The grass area in question was “solarized” (sod lifted, raked, dug, sifted, amended) and sown with dwarf rye grass two or three years back. The effort was to remove the clover that brought honey bees too close to the play area, (allergic to bees). The clover is under control, but the second season after sowing I noticed the brown patches in the new grass. At first I thought it might be urine, crane fly or some grub. Spring growth the next season sort of filled in the dead grass areas and concerns were put at rest. I did lift some sod but found no obvious intruders. Currently, there are more (new) brown spots in the grass and the older brown spots now support this pink gelatinous curiosity. Any insight as to this pink visitor would be appreciated.

– Multnomah County

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Courtesy of OSU Extension Service

A: This sounds like red thread lawn disease caused by the fungus Laetisaria fuciformis. This article, Lawn and Turf Red Thread, gives more information. The signs are red threads from the tips of the grass blades and pink gelatinous globs. It appears in fall, winter and early spring. When the weather warms up and the grass is growing well, you won’t see it. To confirm you can either send or take a sample of your lawn grass near the pink globs to your local Master Gardener office. They can look at the grass through a microscope.

To control red thread, fertilize your lawn with high nitrogen, but balanced fertilizer. Red thread occurs more frequently in undernourished turf. When you mow, use a grass catcher and dispose of the grass tips with the fungus. Disinfecting the soles of your shoes and the underside of your mower with bleach diluted 1 part to 10 parts water can also help. The Common Sense Gardening Guide to Lawn Care has good information on growing lawns and a discussion of red thread on page 12.

– Anne Schmidt, OSU Extension Master Gardener

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Courtesy of OSU Extension Service

What’s that fuzzy stuff on this jade plant?

Q: I just noticed this white fuzzy stuff on my jade plant on the stem near the leaves. What is it? How do I get rid of it and stop it from spreading and happening again? Will it spread to the plants I have around it? I am only watering it once a month and just watered it on the first of the month. It does have drainage in the bottom of the pot.

– Multnomah County

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A: The image clearly displays mealybugs, common insect pests of indoor plants.

Yes, they can spread to your other indoor plants. (A hint to avoid problems indoors: Whenever you obtain a new plant, isolate it for at least a month even as you check periodically for unrecognized hitchhiking insects and or diseases.)

Mealybugs move very slowly. They normally develop a white, waxy coating, which tends to repel certain pesticides. Even so, you can easily kill them with direct hits of alcohol, applied as a fine spray; repeat as needed.

Please be aware that jade plants are succulent plants. As such they are extremely sensitive to certain pesticides. Before you obtain any other product as a remedy for them, ask the retailer if the product is safe to use on succulent plants grown indoors.

– Jean Natter, OSU Extension Master Gardener

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Doug fir mystery

Q: We have noticed that a very tall older Doug fir some 100 feet behind our house is full of tiny green glowing orbs at night. Insects of some kind? These are very bright and can be easily seen after dark with the naked eye. We looked at them with binoculars last night and we could see many more – hundreds! They appear to be on the needles as well as the trunk of the tree. We have also spotted a few on the huge Doug fir behind our house also, but so far none on the huge Doug fir in front of our house. Do you know what these are and if they cause damage to the tree? They are quite an interesting phenomenon that I have never seen before.

– Multnomah County

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A: Douglas fir glowworm (Pterotus obscuripennis) is most likely, as it is the right time of year to see them. You’ll find information online about them and they are not anything to try to remove from the trees.

Bugguide has photos of both the adult and larvae.

– Jacki Dougan, OSU Extension Master Gardener

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Watering airplants

Q: I think my airplants are overwatered. What to do?

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A: I referred to the book “Tillandsias II,” by Paul T. Isley III, for detailed information on these fascinating plants.

Let me give you the signs of over-watering, first. Starting with the innermost leaves, tug one gently. If the leaf comes off and the base is dark, there’s a problem. But, this might not be the end. Continue to remove these darkened leaves. Isley says that if even a few healthy leaves remain, the plant may still recover.

Tillandsias should not be planted in soil or left in water. They should be submerged in water once or twice a week for up to 12 hours, but not for more than a day or they can “drown.” Shake the plant off and place it back in its container or holder. In the low humidity of the winter home, misting the plant occasionally wouldn’t hurt, but that is not a substitute for a dip.

Under-watering is more common. Watch for the leaves to curl inward. Increase the frequency of watering, if this happens, but not the amount of time the plant is in the water.

Several sources warn of hard water that is “softened.” In general, tap water should be fine.

I am includingout of Illinois. They have a somewhat different environment than Clackamas County, but the care guidelines match up with Isley’s.

– Claudia Groth, OSU Extension Master Gardener

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More advice from the experts

  • How to control gnats in houseplants
  • To top or not to top trees?
  • How do you treat a stem canker in a maple tree?
  • How to control creeping bamboo and salal
  • How to prune hydrangea and eradicate tree of heaven
  • What’s the best grass seed for Portland lawns?
  • What causes yellow leaves on Oregon myrtle

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Lawn turning red?


Watered = check
Used sharp blades to cut your turf = check
Set your mower deck to 3 inches = check
Not cutting off more than 1/3 of the blade when you mow = check
Fertilizing = check (more below)

And you still have an odd thing happening in your lawn where it seems to be dead grass but it has a tan or pink tint to it? Are they less than 1 foot in diameter? Hello Red Thread!

Red thread takes its name from the antler-like structures (sclerotia) produced by a fungus (Laetisaria fuciformis) on the tips of infected leaf blades.

Red Thread is a fungus that lawns get when they are over watered or there is too much rain (June 2013 in Connecticut!) and the nitrogen leeches out. The grass plants commonly affected by red thread include: Kentucky blue grass, perennial ryegrass and tall fescue.

What can you do to prevent it? Proper nitrogen in your soil is the beginning place to rid your turf of red thread. It may take up to 3 years of a full cycle nutrient program (5 applications for synthetic and 4 applications for organic) to rid your turf of red thread. In exceptionally rainy season (2013) you may need an extra application.

The good news is that red thread is a cosmetic fungus for the most part and it is only controlled by pesticides on sports turf and high value turf (think estates).

Stacy Skoldberg is managing partner of GreenSprays an organic lawn care company specializing in organic tick sprays and fertilizer. Follow her on Twitter or Facebook.

What is Red Thread?

Red thread, caused by a fungus, is favored by cool, humid weather. Red thread mostly attacks lawns with fescue and ryegrass, and has been found severe in some lawns with bluegrass. Initial symptoms of red thread appear as water soaked lesions on the leaves. The lesions enlarge across the leaf which causes blighting or withering. The color can be tan to light straw color. This results in round patches in the turf approximately 1-2” in diameter. The patches may expand to form irregular shapes up to 18” in diameter.

What are the signs?
Red thread can be easily identified by the observation of pink to yellow to red branched, strands of red hairs extending up to 1/8” above the leaf tips and by pink to red, cottony or fuzzy hairs on the leaf blade, especially under humid conditions.

The best temperature for red thread to develop is 68-75 degrees. It usually occurs from midspring to early summer and in early fall on slow growing turf. A water saturated atmosphere associated with prolonged light rain increases red thread development.

Fertilizing will help the lawn to recover quickly and allow the lawn to grow out of the disease. You don’t want to deprive your soil of nitrogen during this time. A balanced rate of slow release granular fertilizer should be applied regularly. Deep watering in the morning hours and never in the afternoon or evening will help to reduce the damage. Avoid light frequent watering, this will make the disease worse. Collecting the grass clippings while the disease is active will help stop the spread.

Controlling Pink Fungus In Lawns: Pink Patch And Red Thread In Grass

There are all kinds of diseases and pests that can adversely affect your turf grass. Soggy pink stuff in lawns or reddish grass are signs of a common turf disease. The effect is caused by one of two different fungi, which appear under very different conditions. For the most part, the question of how to get rid of pink fungus or red thread in grass is moot as it is caused by climate conditions. Controlling pink fungus on lawns requires cultural management and good quality sod care.

Pink Stuff in Lawns

That pink stuff in lawns is Limonomyces roseipelli, a fungus that produces cotton candy like spores and pink gooey fungal growth. The affected grass blades may turn tan to pink in a circular pattern. The area may be 2 to 4 inches in diameter.

Pink patch on grass is a slow growing fungus that doesn’t cause much harm. The problem could also be pink snow mold in grass, but this only appears after snow melts. It is also a fungus that survives dry periods as dormant mycelia and then blooms when cool, wet conditions arrive. This problem is less common and easily managed in established lawns that are well thatched.

Red Thread in Grass

Pink patch on grass was once thought to be the same as red thread but it is now known to be a different fungus. Red thread in grass is caused by Laetisaria fuciformis and appears as red strings in among the dying grass blades.

The condition arises in drier conditions than the pink patch disease and spreads more quickly with more detrimental results. Spring and fall are the most common periods to see this disease. Because this fungus thrives in moist, cool weather, it is not possible to completely control it, but careful cultivation practices can minimize damage and appearance.

How to Get Rid of Pink Fungus and Red Thread

Healthy vigorous grass is able to withstand minor disease and insect infestations. Before you ever lay sod, make sure the pH is between 6.5 and 7.0.

Water infrequently and deeply in the morning so grass blades have time to dry quickly. Let in plenty of light to your lawn area by keeping trees and plants pruned back. Aerate and thatch to improve air circulation and water movement.

Fertilize in spring with the proper amount of nitrogen, as both pink patch on grass and red thread thrive in nitrogen poor soils.

Controlling pink fungus in lawns and other turf diseases starts with these types of good cultivation practices. Fungicides are rarely necessary except in extreme cases and are not 100% effective in all infections.

Reports on Plant Diseases


Red thread is caused by the fungus Laetisaria fuciformis (formerly called Corticium fuciforme). In Illinois, this disease is of chief concern when it attacks the grass blades and leaf sheaths of fine-leaf fescues (red and chewings), Kentucky and annual bluegrasses, perennial ryegrass, and bentgrasses during cool, damp weather in the spring and fall. Fine-leaved fescues and perennial ryegrasses are very susceptible. Velvet bentgrass cultivars are more susceptible than colonial and creeping bents. Other grasses that are sus- ceptible include bermudagrass, redtop, sheep fescue, tall fescue, hard fescue, velvetgrass, zoysiagrasses, and quackgrass. Although red thread rarely kills turfgrass plants outright, it does weaken them and contributes to their decline and death from subsequent stress diseases.

Red thread is an important disease, especially on slow-growing, nitrogen-deficient turf in the cooler and more humid areas of the Northeast, Pacific Northwest, and in the Midwest during excessively moist weather in the spring and autumn. Red thread has even been found growing under the snow. The disease is favored by slow-growing, nitrogen-deficient turfgrass, excess thatch, low calcium levels in the soil, water stress, a sudden drop in temperature, misused herbicides, and exhibits weakening from attack by other pathogens.

Figure 1. Red thread infecting South Dakota Common Kentucky bluegrass. Note the fungus mycelia binding the leaf blades together.

Figure 2. Close-up of the branched gelatinous masses of the red thread fungus. The mycelial mats harden and become blood-red “threads” (courtesy of R.W. Smiley).


The Laetisaria fungus forms conspicuous, pale to bright coral pink, orange, or red mycelial masses on the grass blades and leaf sheaths. In moisture-saturated air, the gelatinous mycelial masses may completely cover the leaves, being bound by a delicate pinkish web of mycelia that also mats the blades and leaf sheaths together (Figure 1). The gelatinous masses, usually 1/16 to 1/4 inch long, are formed by strands of branched hyphae. They often protrude from the tips of grass blades and leaf sheaths as pointed and sometimes as branched, antler-like appendages (Figure 2). The bright coral-pink to blood-red mycelial mats harden and become threadlike (red threads) and brittle when they dry, and function as sclerotia.

Initially, small patches of infected blades and leaf sheaths appear to be partially or completely water-soaked. They shrivel and die rapidly and fade to a bleached tan when dry. Death usually progresses from the leaf tip downward. Where infection is severe, diseased turf is bleached tan, yellowed, or “scorched” in roughly circular- to irregular-shaped patches, varying from an inch to more than 1 feet in diameter. Dead leaves are generally interspersed with apparently healthy leaves, giving diseased turf a scorched and ragged appearance (Figure 3). The spots may be scattered within a turf area, or a number of patches may merge to form large, irregular areas of blighted turfgrass with a reddish-brown or tan cast. Only the leaves and sheaths are infected.

Figure 3. Red thread in red fescue turf (courtesy of D.H. Scott).

Disease Cycle

The Laetisaria fungus survives from season to season as threads of dried, dormant mycelium on the leaves and in the debris of previously infected plants. The fungus is disseminated to healthy turf areas by bits of red threads and microscopic spores (arthroconidia and basidiospores) and as dormant mycelium in infected leaf tissue. Spreading occurs by splashing or flowing water and by wind, shoes, mowers, and other turfgrass equipment. Infection and disease development are favored by air temperatures of 60 to 75 F (15 to 24 C) coupled with prolonged periods of overcast weather, light rains, heavy dews, fog, and moisture-saturated air. The red threads and dormant mycelia resume growth, and hyphae penetrate unwounded leaves through stomates or cut tips when free moisture exists on leaf surfaces and the proper temperature becomes suitable for disease development. The infection quickly spreads throughout the leaf tissues. Water-soaked leaf spots are evident 24 to 48 hours after penetration has taken place. The pinkish mycelial masses can be seen within another day or two. The fungus may be spread rapidly from plant to plant by cobwebby, pinkish mycelial growth from the gelatinous masses on infected leaves.

Growth and disease development essentially stop below 33 and above 86 F (1 to 30 C). However, the causal fungus can survive extremes in temperature. Mycelial growth in infected leaves or from mycelial mats continues when conditions are again favorable.

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Cultural Practices

1. Maintain adequate and balanced soil fertility, based on soil test reports and the recommended turfgrass-fertilization program for your area and the grasses grown there. Red thread is most severe where potassium, phosphorus, calcium, and especially nitrogen are deficient. Avoid overstimulation from fertilizer, particularly fertilizer with a water-soluble, high-nitrogen source.

2. Where red thread has been a problem in the past, maintain a soil reaction (pH) between 6.5 and 7.0. Test the soil pH, and treat the soil accordingly if practical.

3. Increase light penetration, air movement, and rapid drying of the grass surface by pruning or selectively removing dense trees and shrubs that border the turf. When landscaping, space plantings properly to avoid excess shade and allow for adequate air movement.

4. Avoid overwatering and frequent sprinkling in the late afternoon or evening. During summer or early fall drought periods, water established turf thoroughly early in the day so that the grass surface can dry before night. Water infrequently and deeply, moistening the soil at each watering to a depth of 6 inches or more.

5. Provide for good soil drainage when establishing a new turfgrass area.

6. Remove excess thatch, preferably in late summer or early fall, when it accumulates to 1/2 inch. Use a “vertical mower”, “power rake”, or similar equipment. This equipment can be rented at many large garden supply or tool rental stores.

7. Mow frequently at the height recommended for the area and for the grasses grown there. Mow upright grasses, such as Kentucky bluegrass, ryegrasses, and fescues, at 1½ to 2 inches in spring and fall; 2½ to 3 inches in the summer. Creeping grasses, such as bentgrass and bermudagrass, may be mowed to 1/2 inch or less. Remove no more than one-fourth to one-third of the leaf surface at one cutting.

8. Collect the clippings during periods when the grass is growing slowly and the disease is active. This may reduce the number of red threads that eventually fall back into the turf.

9. Improved perennial ryegrasses reported as being resistant to red thread include Birdie II, Citation II, Linn, Pennant, Pippin, Premier, and Tara.

Some fine-leaf fescue cultivars that are resistant or moderately resistant to red thread include Atlanta, Aurora, Bighorn, Biljart, Dawson, Epsom, Flyer, Golfrood, Reliant, Scaldis, Shadow, Spartan, Valda, Waldina, Weekend, and Wintergreen. Susceptible fine-leaf fescues are Boreal, Ceres, Commodore, Ensylva, and Ruby. Hard fescues are often overseeded where red thread is a serious problem.

Somewhat resistant Kentucky bluegrass cultivars resistant to red thread and other diseases are listed in Table 1. Other resistant Kentucky bluegrasses include Adelphi, Admiral, Aspen, Banff, Barblue, Bonnieblue, Bono, Bristol, Classic, Dormie, Eclipse, Haga, Harmony, Holiday, Merit, Midnight, Mona, Mosa, Nassau, Ram I, Trenton, and Welcome. Susceptible Kentucky bluegrasses include Apart, Argyle, A-34 or Bensun, Glade, Kenblue, Mystic, South Dakota common or certified, and Sydsport.
Fungicide Applications

Where red thread has been troublesome, apply a suggested fungicide at 7- to 21-day intervals during moist weather in the spring and fall, when daytime temperatures average between 65 and 75 F (18 to 24 C). Begin spray applications when the disease is first evident. For the most effective control, uniformly spray 1,000 square feet of turf with 5 to 10 gallons of water that contain only one of the fungicides listed for red thread in the current edition of Illinois Homeowner’s Guide to Pest Management.

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Pink patch, formerly thought to be a form of red thread and caused by the fungus Limonomyces roseipellis, is a minor disease of frequently mowed grass. Apparently, the disease is restricted to perennial rygrass, Kentucky bluegrass, creeping red and chewings fescues, creeping bentgrass, bermudagrass, and zoysiagrass. Pink patch is much more severe on either unmowed or infrequently mowed grasses that are grown under low nitrogen fertilization than it is on highly maintained turfgrasses.

Although patches generally remain green, diseased turf may have a tannish cast. Affected areas are irregularly shaped in coarse-textured turf, but distinct pinkish patches, two to six inches across, occur in creeping bentgrass (Figure 4). The disease occurs in spring and autumn during prolonged periods of heavy dews, light rains, and fog on turfs with inadequate nitrogen fertility. Small, irregularly-shaped areas of turf become covered with a pink to reddish film of mycelium that tends to form first along the leaf margins. Later, the entire width of the leaf blade is covered. Only leaves and sheaths are infected, and diseased leaves die from the tip downward.

There are three key diagnostic characteristics that are used to separate pink patch and rd thread: the red threads and arthroconidia are not produced by the pink patch fungus, and hyphae of the Limonomyces fungus have clamp connections whereas the hyphae of the red thread fungus do not.

Figure 4. Pink patch infecting creeping bentgrass. Patches are two to six inches across (courtesy P.H. Demoeden).

The disease cycle of pink patch is similar to that of red thread, except for the absence of arthroconidia and red threads.


Control measures are usually not necessary on mowed turfs. Mow frequently at the recommended height of cut for the grass or grasses that are grown. Fertilize on the basis of soil test recommendations, as outlined for the control of red threads.

Table 1. Modern Kentucky Bluegrass Cultivars Adapted to Illinois and Reported to be Moderately to Highly Resistant (R)a to one or More Diseases

Kentucky Bluegrass Cultivars “Helminthosporium” diseases Leaf Smuts Leaf and stem rust Summer patch & necrotic ringspot Sclerotinia dollar spot Typhula blight Septoria leaf spot Red thread



A-34 (Bensun)

a A resistant (R) rating does not mean that a particular cultivar will be resistant in all locations every year. Due to the presence of physiological races or strains of the various fungi that cause these diseases, a cultivar may be susceptible in one locality and highly resistant in another. This is especially true of powdery mildew and is the reason we omitted this disease from our ratings.

b A blank under a given disease does not necessarily indicate susceptibility. In some cases it means that no data are available on which to evaluate the relative susceptibility or resistance to a particular disease.

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Pink Snow Mold

Scientific Name: Microdochium nivale

Common Names: Microdochium Patch, Fusarium Patch

Primary Grass Affected: Almost all cool season turfgrasses, including Ryegrasses, Annual Bluegrass, and Kentucky Bluegrass

Brief Description: Pale, matted circular patches several inches in diameter, with pinkish, salmon-colored or rust-colored edges.

What is Pink Snow Mold?

Pink Snow Mold is a fungal lawn disease caused by the fungus Microdochium nivale. It is one of two types of snow mold. The other type, called Gray Snow Mold or Typhula Blight, often occurs in conjunction with the pink variety and is less harmful to turfgrasses. Both types of Snow Mold occur when heat and moisture become trapped beneath a layer of snow, creating ideal conditions for the fungus to grow in.

Pink Snow Mold harms turfgrass by attacking the roots and the crowns of the grass, which does longer-lasting damage to your lawn. Both Pink and Gray Snow Mold are capable of invisibly surviving the summer in the form of fungal spores to appear again the next spring.

Signs and Symptoms of Pink Snow Mold

This lawn disease usually appears in the spring, as the snow melts and reveals the disease that has been thriving underneath. At this point, the colors of pink snow mold will be the most vivid. As the grass dries, the colorful mycelium or fuzzy, mold-like coating that gives the grass its matted appearance starts to fade.

As the weather warms, the circular patches of grass affected by the disease will die, leaving brown patches that, depending on the damage to the roots and the size of the affected area, may need to be reseeded. It is important to remember that, even if the patches do grow back over the course of the year, the mycelium or spores may still be present in the lawn, and are capable of surviving warmer conditions.

How to Prevent Pink Snow Mold

Preventing Pink Snow Mold if you’ve never had it before is generally as simple as preparing your lawn for the winter in such a way that warmth and moisture are less likely to get trapped beneath falling snow. In the autumn you should carefully rake up the leaves that fall and remove any unnecessary items from your lawn that may get between your grass and the snow, such as fallen sticks, pine cones or wading pools or waterslides no longer in use. Clearing the lawn of debris will prevent warm “microclimates” from forming underneath them.

If you have had Pink Snow Mold before, chances are the spores are still present in your lawn. In order to eradicate them, a fungicide treatment may be required. As with most fungal lawn diseases, Pink Snow Mold may require more than one treatment to eradicate completely.

Need Help with Pink Snow Mold?

Call Green Lawn Fertilizing today at 888-581-5296 and let’s talk about how we can help you with Pink Snow Mold and other lawn diseases.

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One of the more common late spring to early summer diseases on cool-season grasses is Red Thread lawn disease. It is most severe on Kentucky Bluegrass, Perennial Ryegrass and Tall Fescue. There is another lawn disease that occurs at the same time and under the same environmental conditions known as Pink Patch.

The main difference between the two lawn diseases are the fruiting structures. Red Thread takes its name from the red thread-like structures called sclerotia that are produced by the fungus. Pink Patch produces tiny puffs of pink-cottony mycelium that resemble little bits of cotton candy stuck to the grass blades. Of the two diseases, Red Thread is the more common one seen in home lawns. Red Thread may develop when temperatures range from 40 to 75°F. Most grass activity occurs when temperatures range 65 to 75°F and during periods of cool, cloudy weather with long periods of evening dew.

What Does Red Thread Lawn Disease Look Like?

Symptoms are often visible from the street as circular patches of tan or pink grass about 4-8 inches in diameter. Upon closer inspection, the sclerotia are easily visible, appearing like small, red threads protruding out of the grass blades, especially near the tip. Red Thread will affect the leaves, leaf sheaths and stems without killing the entire plant, unless the outbreak is severe. The infection begins as small blighted areas on leaves and rapidly enlarge, covering the entire leaf blade. The affected leaves will dry out and turn a bleached straw color.

After it has completed its life cycle, the disease produces the red threads or sclerotia. In other words, unless the weather conditions last a long time, the red threads signal the end of its activity. These threads will break off and act as “seeds” for future outbreaks of the disease. Mowing infected areas has little impact on spreading the disease so collecting clippings during this period is not very beneficial.

How To Treat Red Thread Lawn Disease

It is important to maintain an adequate nitrogen fertility program to lessen the effects of Red Thread. Fertilization after an outbreak of Red Thread will help the turf to “grow out” of the effects of the disease activity. Fertilizer will help the lawn grow and then the diseased parts of the plant can be mowed off to allow newer, healthy blades to grow. Avoid excessive watering during cool, cloudy periods that may extend the time the turf remains wet. Core aeration and overseeding with improved varieties of turf grasses that are more resistant to Red Thread are another two important cultural practices.

There are chemical control options, but by the time the red threads are seen, it is usually too late to apply a preventative disease control application. Making sure the lawn is well fertilized, mowed properly and receives the right amount of water on a weekly basis is the best approach to take when dealing with Red Thread lawn disease.

If Red Thread is a problem in your lawn, contact your neighborhood lawn care professional at Spring-Green. They will be happy to inspect your yard and provide a beneficial lawn care program.

Scientific Name: Laetisaria fuciformis

Primary Grass Affected: Kentucky Bluegrass, Fescue, Perennial Ryegrass

Brief Description: Tall reddish “thread” that grows above the grass blade.

What is Red Thread

While no one wants their lawn to be infected with disease, red thread is perhaps one of the most desirable. Unlike other lawn diseases, red thread does not kill grass. Instead, it simply grows on top of grass as a host. Red thread also may not re-infect your lawn in the future provided you treat it correctly, unlike other fungi that can continue to infect grass without extensive treatment.

It prefers cool conditions and is more common in spring and fall than summer. It is also more likely to occur if the turf isn’t receiving the proper amount of nutrition.

Signs and Symptoms of Red Thread

Red thread creates small patches of reddish tinted grass that from a distance may make the grass appear dead. These patches are often confused with dollar spots and other lawn diseases. But upon close inspection it is easy to see the red, thread like material that seems to grow out of the top of grass while the blades themselves remain intact.

There may also be a pink fluffy material named “mycelium” that can be found on the bottom of the blades of grass.

How to Prevent Red Thread

The simplest way to control red thread is to use nitrogen based fertilizers. Red thread can be drastically reduced when a lawn receives nitrogen based fertilization for several years. Like many other types of fungi, it is also important to make sure that you avoid watering your lawn late at night when the moisture will stay in the ground for too long and become dew the next morning.

Because the disease is mostly a visual problem, rather than a lawn health problem like many other types of lawns diseases, treatment may not be necessary. Often the red thread will go away on its own through general lawn maintenance. But when red thread becomes too pronounced or you are looking for a more immediate treatment, fungicides may be used and have a high success rate.

Need Help with Red Thread?

Call Green Lawn Fertilizing today at 888-581-5296 and let’s talk about how we can help you with Red Thread and other lawn diseases.

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