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What Is Dollar Spot Fungus

What Causes It To Develop

How to Prevent Dollar Spot Fungus |

Dollar Spot is caused by a fungus called Sclerotinia homeocarpa, which lives in most turfs.

During the Winter it lies dormant in the soil and thatch layer. Then when conditions are right, the fungal spores become active which encourages the disease to develop.

Dollar Spot occurs in periods of hot days with high humidity followed by cool nights. Usually in the Summer and Autumn.

Any situation that causes your lawn to stay damp for long periods of time will contribute to the development of Dollar Spot Disease.

These include

  • Excess lawn thatch
  • Soil Compaction

Low Nitrogen levels in the lawn and cutting the grass too short during hot weather will often stress the grass which can increase the chances and the severity of an attack.

What Causes Dollar Spot Fungus

When temperatures are 6085 and nighttime conditions are especially moist, dollar spot fungus thrives. Lawn moisture can be caused by rain or heavy dew formation on cool nights. Most often, dollar spot appears in early spring and persists through late spring into summer, where summer heat eventually halts it.

Dont wait for hot, dry conditions to stop the fungus for you. Dollar spot can do a lot of damage to your yard in a single season.

Dollar Spot And Leaf Spot

May 15, 2015

Over the last week, dollar spot and leaf spot have popped up across the state of Iowa.

Dollar spot is usually considered an early to mid-summer disease and seems to be about a month ahead of last year. It is caused by the fungal organism Sclerotinia homoeocarpa. Most of the damage I have seen this spring has occurred on bentgrass greens, tees, and fairways. The symptoms of dollar spot on close mown turf are small, tan-colored spot equal to or smaller than 2.5 inches across. The name of Dollar Spot comes from the silver dollar-sized turf damage. Spots can be numerous and coalesce, making identification difficult. Dollar spot is most notable on nitrogen deficient turf. By increasing fertility, you can reduce future outbreaks. Dollar spot can spread by movement of mowers, equipment, water, wind, and people. It has a very wide range of activity. It is most active in temperatures between 60-90 degrees but can occur as long as nights are over 50 degrees . The wet weather/ and high humidity have created an ideal situation for early season dollar spot.

Pictures courtesy of Cody Freeman – Green King Turf

Leaf spot is an Ascomycete fungi caused by Bipolaris spp. and/or Dreschslera spp. Cool, wet weather favors the disease. Leaf spot affects all turfgrass species used in the state of Iowa. A majority of the damage recorded so far has been on Kentucky bluegrass lawns and golf course roughs. It can also hit bentgrass, fine and tall fescue, and ryegrass.

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How To Treat Dollar Spot Disease

Dollar Spot disease is caused by the fungus Sclerotinia Homoeocarpa and is common in both warm and cool season grasses across Australia.

Dollar Spot can lie dormant over winter and become active again when conditions are more favourable, such as warm humid days, cool nights, and heavy dews.

Its most common in spring and autumn, and especially prevalent in dry soils that are low in nitrogen.

Small outbreaks are unlikely to jeopardise the health of your lawn but left untreated Dollar Spot can develop into a major problem and ruin your lawns appearance.

How To Identify And Control Dollar Spot

Turf: Dollar Spot

Find out if those straw-colored patches are dollar spotand what to do if they are.

When clusters of small, round, sunken patches of straw-colored grass about the size of a silver dollar start showing up on your otherwise beautiful green lawn, theres a good chance the culprit is a fungus called dollar spot. Once primarily known for wreaking havoc on golf courses and recreational turf, dollar spot has become a common lawn problem for homeowners as well.

Dollar spot affects most types of warm- and cool-season grasses, but especially fescues, ryegrasses, bentgrasses, bluegrasses, bermudagrasses, and zoysiagrasses. It tends to occur from late spring to late fall, especially after a period of extremely moist weather. Dollar spot favors high humidity and temperatures ranging from 60 to 85 degrees F.

The bad news: How you care for your lawn can actually stimulate the spread of dollar spot. The good news? Theres plenty you can do to help control it.

Here are 3 reasons your lawn may have dollar spot and what to do about it.

The cause: Mowing too closely.

Because they hold moisture on grass leaves, short lawns are more susceptible to dollar spot infection.

The fix: Adjust your cutting height. Raise your mower blade to the recommended 3 to 4 inches. The exception is zoysiagrass, which can be cut a little shorter . Never cut more than one-third of your lawns grass length at a time, no matter how tall it gets.

The cause: Not enough lawn food.

The cause: Persistently wet leaves.

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What Causes Dollar Spot

Dollar Spot is a turf disease effecting many different turf varieties. As its name suggests, the appearance of this disease is usually identifiable as dollar sized spots of discoloured grass appearing within your lawn. Up close, the discoloured leaves will have straw coloured lesions with red/brown edges to them. If left to spread the spots will get larger and form bigger patches of affected grass.

Another identifying feature of Dollar Spot is the web like fine threads that form through the leaves of your lawn on colder mornings. These webs will disappear as the day warms up, but these threads are called mycelium threads and are a product of the fungal pathogen known as Sclerotinia Homoeocarpa.

Description Of The Disease

Dollar spot affects small, circular areas of turf, about 1 to 5 inches in diameter. Spots may merge to form large, irregular areas. Leaves appear water-soaked initially, then brown and often exhibit a reddish band extending across the leaf. Lesions on leaves often have a distinctive “hourglass” shape with necrosis on the outer edges of the leaf blade and healthy tissue in the middle. Fine, white, cobwebby hyphae may be seen in early morning. The fungus survives as mycelia or stromata on plants or in plant debris during periods of unfavorable weather conditions.

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Dollar Spot Signs And Symptoms

True to their name, dollar spots are small, round patches. Usually resembling the size of a silver dollar, they can grow to more than six inches wide. Dollar spots are often overlooked at first on home lawns where the infection is small at first and appears to be nothing more than a tiny dead spot. They are also often mistaken for urine patches left by an animal.

Dollar spots become easier to recognize when closely inspected. The blades exhibit several common symptoms: white mycelium grows on the affected area in the morning and fades to a brown, tannish color after sun exposure. The blade often has a purple or light-brown color, as well.

How To Control Dollar Spot Disease

Dollar Spot Lawn Fungus | Disease Control and Prevention

Adopting good lawn care practices is the best way to correct Dollar Spot, but if the outbreak is severe you might need help from a fungicide.

Look for contact fungicides containing the active ingredients chlorothalonil or iprodione, or systemic fungicides containing the active ingredient propiconazole.

Liquid fungicides, which require less measuring and mixing, are generally the easiest to use. They also dont usually need to be watered into the soil.

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Why Do You Have Dollar Spot

A little bit of Dollar Spot during the Summer is normal and nothing to worry about. If you have a severe case, here are some issues that will make dollar spot worse:

IMPROPER WATERINGDollar Spot Disease occurs when the surface of the lawn stays wet and the soil is dry. Watering too often and too lightly will result in a lot of Dollar Spot. Our suggested solution is to switch to watering deeply every 3-4 days, roughly one inch of water per session.

HEAVY THATCHA thick thatch layer is the perfect breeding ground for Dollar Spot fungi. In addition to providing a good home for the fungus, a heavy thatch layer keeps water on the surface of the soil and prevents it from reaching the roots. These are exactly the conditions that cause the Dollar Spot fungi to thrive. As a good start, we recommend fertilizing organically. Ultimately however, you need to reduce thatch. Core Aeration and Liquid Aeration help water to penetrate the soil and lessen the amount of thatch you have. You can also try Organic Compost Topdressing in the Fall, which will provide good biology that can both decompose thatch and fight off the fungi that cause Dollar Spot Disease to form. Contact us for details on which services would be best for you.

Dollar Spot Fungus On Your Lawn

Dollar spot fungus is a pest that invades lawns, killing grass. If your lawn has been stricken with dollar spot fungus, use the following methods to save your grass.

  • Water infrequently and only water in the morning.
  • Apply a high-nitrogen fertilizer.
  • Mow your lawn at a higher blade height.
  • Clear your lawn of leaves and debris.
  • Dethatch your grass.
  • Bag and dispose of grass clippings.
  • Use a fungicide to kill dollar spot fungus.

This invasive fungus can attack most turfgrass species, including Bermuda Grass, Ryegrass, Fescue, Bentgrass, Kentucky Bluegrass, and Zoysia. If your lawn is being attacked, take immediate action before the fungus spreads.

  • How to Identify and Control Dollar Spot Fungus
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    Fertilise Your Lawn In Spring And Autumn

    Dollar Spot Disease attacks lawns that are deficient in Nitrogen.

    By fertilising your lawn in the Spring with a slow-release lawn feed, youll give your lawn the Nitrogen and other nutrients it needs to grow, stay healthy and fight off disease through the Summer.

    Again, feeding your lawn again in the Autumn with an Autumn feed will provide it with the nutrients it needs to stay healthy during the damper weather.

    Damage Symptoms: How You Can Spot It

    Dollar Spot Fungus

    There are two easy ways to identify dollar spot lawn disease on turf. The first is the shape and size of the damaged areas. The individual spots are usually very circular and distinct, and grow to only a few inches in diameter. Another symptom thats easy to recognize are the lesions on the individual grass blades. Dollar spot lawn disease causes an hour-glass shaped band to form across the width of the grass blade. This band is light tan and has a reddish-brown edge on the top and bottom. Being a very thorough fungus, dollar spot kills the entire grass plant. After a serious bout with dollar spot, lawn renovation or reseeding will almost always be required once the disease is brought under control.

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    Tips For How To Get Rid Of Dollar Spot Fungus

    Known for afflicting golf courses, dollar spot fungus commonly attacks lawns, starting in spring. Because almost all grass species are at risk for dollar spot, its common across many regions. An especially wet spring may cause a lawn invasion unlike any before. Read on to discover ways to fight back and kill this fungus.

    What Is Dollar Spot Disease

    Dollar Spot Disease isnt very prevalent in the UK. That being said, it is becoming more common.

    Its a fungal disease which mainly affects ornamental lawns made up of fescue grasses. Creeping Red Fescue is most prone to an attack and more and more suppliers include it in their grass seed mixtures.

    It can also affect bent grasses and Annual Meadow Grass.

    This is why its becoming more common.

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    Why Does Your Lawn Have Dollar Spot

    Depending on how you treat your lawn, dollar spot could be caused unintentionally by improper maintenance.

    • Persistently wet grassSince dollar spot loves humidity, extended periods of wet weather can lead to the disease on susceptible grasses. While you cant control the weather, you can control your lawn watering habits. Water your lawn deeply and infrequently. Watering in the early morning hours will also prevent the grass from staying moist for too long. If you are experiencing a lengthy period of rain, let mother nature take care of the watering until it gets dry again.
    • Mowing too shortShorter lawns will hold onto moisture for longer, which makes them more susceptible to contracting dollar spot. In order to prevent this, raise your mower blade to be around 3-4 inches. As a good rule of thumb, try not to cut more than one-third of your lawns leaf blades at a time.
    • Thatch build upIf your lawn is building up with thatch, this can be a trigger for dollar spot. Thatch buildup can prevent the necessary amount of oxygen from getting into the soil.
    • Not enough lawn foodLawns that are not receiving the proper amount of fertilizer can be prone to diseases like dollar spot. Depending on your grass, make sure your lawn is being treated with the correct fertilizer and required amount.

    What Is Dollar Spot Lawn Disease

    Dollar Spot Fungus in a Lawn

    Dollar spot, a lawn disease that affects a wide range of turfgrasses throughout most of the year, is a particularly insidious lawn fungus that can make your beloved turf look like an unsightly patchwork. Here’s what you need to know about dollar spot, and how a TruGreen®-certified specialist can help you regain a lawn you’ll love

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    Signs Of Dollar Spot Fungus

    Knowing what to look for is essential to both treating and preventing Dollar Spot.

    As the name suggests, the first signs can be circular yellow patches about the size of an Australian one dollar coin. The water soaked lesions then become straw-like, with a reddish-brown margin.

    On closely mowed grass, the patches are sunken and can join up to form larger irregular patches.

    They can be mistaken for drought injury or fertiliser burn in taller lawns.

    If youre not sure whats causing the damage, carry out an inspection early in the morning after a cool night or when theres heavy dew on the ground.

    Look for fine threads resembling spider webs or cotton that disappear as the day warms up.

    This is known as mycelium and is the way the fungus spreads from one leaf blade to another. Dollar Spot also can be spread by equipment, wind, soil, people and animals.

    What Does Dollar Spot Look Like

    It appears as small spots of pale or bleached grass, usually an inch or two in diameter. Youll see light tan coloured lesions or infection marks on the grass leaves which have reddish brown edges.

    These spots often sink slightly which causes the surface of your lawn to be uneven.

    On dewy mornings you might see a cobweb-like mould, similar to that of Snow Mould. Then, when the grass dries, the mould tends to become less visible.

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    What Causes Bare Spots In Lawn

    CausesBare SpotsLawnBare spotslawngrassHow you feed, mow and water your lawn can help it resist fungal diseases like dollar spot and brown spot.

  • Stop Them Before They Start.
  • Feed Your Lawn Regularly.
  • If You Need To Water, Water Properly.
  • Mow Regularly at the Right Height.
  • Apply Fungicide if Needed.
  • When Does Dollar Spot Occur

    Dollar Spot Lawn Fungus #dollarspot #lawndisease

    Dollar Spot occurs when there is additional moisture present on warmer days and the cool nights of spring and autumn. Excessive amounts of thatch build up, poor drainage and watering your lawn too often are common factors that can result in the spots appearing. Dollar Spot is much more common in turf under intensely managed conditions, so is commonly experienced on golf courses.

    • High humidity
    • Cool nights with heavy dew
    • Low nitrogen levels

    So often with fungal diseases the best remedy is simply good lawn care practices.

    • Regularly fertilising your lawn throughout the year will prevent nitrogen deficiency.
    • Regular mowing will help to reduce thatch build up, which can create an ideal humid environment for the disease to grow.
    • When watering your lawn, be sure to do so in the mornings and afternoons only and only water your lawn when it really needs it. A long deep soaking will be of much better benefit than many short waterings.

    We generally do not recommend treating with fungicides unless the issue continues to persist after implementing the treatment options above. By treating the cause, you should be able to get Dollar Spot under control without the use of a fungicide.

    Some fungicide options you might want to consider however are Mancozeb and Zaleton Systemic Fungicide, which you can purchase at Bunnings or commercial options Bumper 625 and Chief Aquaflo.

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    How Does Dollar Spot Lawn Fungus Thrive

    Dollar Spot thrives in conditions of dry soils and moist air. When the roots are low on water and the leaves of your grass are wet from dew, rain, or irrigation, outbreaks of this lawn disease increase.

    This lawn fungus is at its worst in summer and seasons marked by high humidity, low rainfall, and temperatures between 60 degrees and 80 degrees Fahrenheit.

    According to the Penn State College of Agricultural Sciences, the fungus spreads via mycelium on infected plant parts . Mycelium can also be carried by the wind, water, or on turf equipment and shoes.

    Identifying Dollar Spot In Grass

    If upon further inspection you see that these are not spider webs that have appeared in your lawn but rather appear to be yellow straw-colored patches in the grass then this can be identified as Dollar Spot Fungus. This fungus sinks in the grass and leaves stringy cotton like residue which gives the false appearance of spider webs in the grass. The main difference being the yellowish color and the absence of grass spiders.

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    Water At The Right Time

    To promote healthy grass and stop the spread of dollar spot, reduce watering frequency to increase dry soil periods and slow the spread of the fungus. Also, water only in the morning. Watering late in the day causes water to sit on the lawn throughout the night, which promotes fungus growth.

    • Water deeply 2 times per week.
    • Water early in the morning .
    • Never water in late afternoon or evening.


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