What is Dollar Spot Fungus?

Photo by A. Martinez for University of Georgia Extension

If you’ve noticed groups of yellow patches emerge throughout your lawn, then your yard might be a victim of Dollar Spot Fungus. 

Though this is a common disease that many lawns encounter, it’s important that you seek assistance from a chemically-licensed lawn care professional when dealing with Dollar Spot Fungus. 

Continue reading to learn:

• What Dollar Spot Fungus Is
• What Causes Dollar Spot Fungus
• What Dollar Spot Fungus Looks Like
• How Dollar Spot Fungus Spreads
• How to Prevent Dollar Spot Fungus
• How to Address Dollar Spot Fungus

For information about other common lawn diseases, visit our Lawn Disease Resource Page.

Dollar Spot Fungus Explained

Dollar Spot Fungus (aka Sclerotinia homoeocarpa) is an endemic disease that affects all turfgrasses. It especially affects cool-season grasses such as bluegrass and bentgrass varieties.

What Causes Dollar Spot Fungus?

Dollar Spot typically appears when there is high humidity during summer months (June-September) or if your lawn is wet, over irrigated, covered with wet leaves, and/or is undernourished.

The fungus takes root when conditions are ideal for producing heavy dew (daytime temperatures are between 65-80 degrees Fahrenheit and nights are cool. Dollar Spot also prefers low levels of nitrogen in the soil as well as dry soil – which is why it occurs in undernourished lawns. 

What Dollar Spot Looks Like

The name “Dollar Spot” describes how affected patches appear. On a short-cut turf – such as a golf course – the grass bleaches in circular silver dollar-size (1-2 inch diameter) spots. On longer turf it produces straw-colored patches that can thin out the grass and allow weeds to invade.

Affected patches will often begin with a cobweb-like mycelium (fungal threads) visible in the morning dew. If you look at individual blades of affected grass you find hourglass lesions running across the blade. The lesions are tan and outlined top and bottom with a reddish-brown stripe.

How Dollar Spot Fungus Spreads

Because it is a fungus, Dollar Spot’s spores can cling to mowers, grass clippings, shoes, animals – virtually anything moving across your lawn – and will rapidly spread throughout your entire lawn, destroying the look and wearability of your lawn.

More money is spent each year on the chemical treatment of Dollar Spot Fungus than any other grass disease, so it’s important to prevent it as much as possible and treat it immediately when spotted.

How to Prevent Dollar Spot Fungus

Prevention is the easiest and cheapest route for dealing with all lawn diseases and especially with Dollar Spot Fungus.

Here’s a quick list of 7 ways to prevent the disease in the first place:

• Establish the right turfgrass for your geographical location, soil type, landscape and use.

• Add light but frequent applications of nitrogen to your lawn, being careful not to over fertilize and overseed when recommended.

• Irrigate before sunrise or early in the morning (not afternoon or night), so dew is not sitting on the grass and moisture has time throughout the day to evaporate off the grass blades. You can also use the effective poling technique by swishing your water hose over the top of the grass to knock off morning dew. Also, avoid exposing your lawn to foot traffic after watering.

• Prune bush or tree canopies to allow for better air circulation and light exposure to increase moisture evaporation.

• Make sure to keep your thatch cover below a 1-inch layer since too much thatch cover can affect drainage and nutrients reaching the soil.

• Avoid low mowing heights (below 2 inches) for cool-season grasses, which stresses the turf.

• Cultivate the soil so that it is not compacted eliminating drought-stress for the turf. Core aeration is a good way to reduce compaction within the soil. 

I Found Dollar Spot Fungus in My Lawn – What Can I Do? 

Before you shop for a chemical fungicide, be aware that there are few options on the retail market for homeowners and that incorrect or over-application can cause the disease to become resistant or immune to the fungicide.

To effectively eliminate Dollar Spot Fungus, The University of Georgia Extension recommends that homeowners seek the assistance of a chemically-licensed lawn care professional to assess the issue.

Lawn care experts have access to a variety of fungicides and will know how and what type of fungicide to use, rotating chemicals so as to prevent resistance. They can also provide routine maintenance to keep the disease from reappearing.

About Simply Green’s Weed Control Service

Simply Green offers a variety of weed control and fertilization programs to meet your specific needs. We will carefully evaluate your lawn to determine the best course of action.

Our weed control services are designed to target specific types of weeds and address the underlying issues that are causing them. Each service is customized based on the type of grass you have, the time of year, and your lawn’s specific needs. We only use high-quality products that are safe for your family and the environment.