Dollar spot fungus (Sclerotinia homoeocarpa) 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.
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What does Dollar Spot Fungus Look Like?
Dollar spot fungus first appears in your grass as spots about the size of a silver dollar that are tan or light brown in color. Straw-colored spots on the grass blade may be ringed with reddish-brown. When viewed closely, especially when moisture is present in the grass, you may be able to see fuzzy, cobweb-like white strands on grass blades. This is the Sclerotinia fungus itself.
If not treated early, the small straw-colored spots can grow to 6 inches or larger in diameter. Large patches of grass can be killed by the fungus if left unchecked.
What Causes Dollar Spot Fungus?
When temperatures are 60–85℉ (15–30℃) 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.
Don’t 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.
7 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, it’s 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.
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 (begin watering before 6 AM).
- Never water in late afternoon or evening.
By watering properly, you can prevent dollar spot fungus, slow its spread, and allow your lawn a chance to fight back.
Apply a high-nitrogen fertilizer to a yard afflicted with dollar spot fungus. Nitrogen promotes grass blade growth and contributes to overall lawn health. Fertilizer will help damaged areas of your lawn recover and create healthier grass throughout your lawn, which will resist infection.
Lawns afflicted with dollar spot fungus may need more nitrogen than healthy lawns. Apply a slow-release nitrogen fertilizer once per month throughout the growing season to help your grass recover from the damage caused by the fungal disease.
Increase Mowing Height
Short lawns (3 inches or shorter) hold more moisture on their grass blades, which leads to dollar spot fungus growth. Reduce leaf wetness by raising your mower blade height. Mow tall grasses such as Bluegrass, Rye, and Fescue at 4 inches.
Low-growing grasses, like Bermuda Grass and Zoysia, tend to have sprawling runners and don’t produce tall leaf blades. Mow these grasses at 1.5–2 inches in height to help combat dollar spot disease.
Clean Your Lawn
Anything that traps moisture on the lawn increases the risk of dollar spot fungus and increases its chance of spreading. Remove dead and wet leaves, plastic tarps, woodpiles, and other elements that keep your grass moist.
Shady, wet areas beneath low growing bushes and shrubs can contribute to dollar spot invasion. Trim low hanging branches to promote airflow and sunlight on your lawn. This simple cleanup will help with dollar spot control.
Thatch is a layer of dead grass between your green, growing grass, and the topsoil. It is notorious for trapping moisture and can breed dollar spot fungus.
Rent a dethatcher or vertical mower to remove excess thatch from your lawn. By dethatching your lawn, the ground will absorb moisture more effectively, feeding your grass and preventing the growth and spread of a dollar spot infection.
Bag Grass Clippings
Dollar spot is a contagious disease. Once it takes hold on a leaf surface it can be spread if an infected blade of grass touches an uninfected grass blade.
To make sure you don’t inadvertently spread dollar spot from one portion of your yard to another, bag grass clippings when you mow. This will keep infected grass clippings from coming into contact with healthy portions of the lawn. You may also consider cleaning mower blades after use to remove any trace of the fungus.
Fungicide applications are the most extreme option for killing dollar spot fungus. Apply a high-quality fungicide labeled for use against dollar spot. Keep in mind, it may take repeat applications to fully kill off the dollar spot lawn disease.
Fungicide resistance is not unheard of when encountering dollar spot. Because dollar spot can put up a battle, cultural practices such as fertilization and proper watering are considered the first course of action when fighting fungal lawn diseases.
Will Dollar Spot Fungus Go Away on its Own?
If temperatures rise above 85℉ (30℃) and the lawn is not excessively moist, then dollar spot fungus will die out. However, don’t count on mother nature to wipe out the fungus. It can do a lot of damage to your green lawn before summer temperatures stop it.
In some cases, dollar spot fungus may linger throughout the summer in shady areas with high soil moisture, then explode into life again in fall, causing a second invasion. Rather than wait for it to come back, attack the dollar spot early to kill it.
How to Identify and Control Dollar Spot Fungus
Dollar spot is one of the worst grass diseases you can have on your lawn. If left unchecked, what begins as bleached, dollar-sized spots on your lawn can spread into a warzone of dead patches of grass.
To fight back against dollar spot, reduce watering to twice per week and water only in the early morning. This reduces nighttime soil moisture, slowing or stopping the spread of dollar spot. Fertilize your lawn to help it battle against the fungus, cut your grass higher, dethatch your lawn, and clear your yard of leaves, debris, and grass clippings.
Finally, use a fungicide to kill dollar spot fungus. Sometimes, this is the only option to reclaim your lawn from this disease.