Dollar Spot Fungus: Causes, Symptoms, and Treatment

Have you noticed small, circular patches of dead grass on your lawn? If that's the case, your lawn could be infected with the dollar spot fungus. This common fungal infection is notorious for causing extensive damage to lawns and golf courses. In this article, we will discuss what causes this fungus, how to detect it, and how to treat it.

Understanding Dollar Spot Fungus

The dollar spot fungus (Sclerotinia homoeocarpa) is a widespread turfgrass disease that affects various species of warm- and cool-season grasses. The fungus got its name from the silver-dollar-sized patches that it forms on the grass blades, which later merge into large dead spots. The disease is most prevalent in humid, warm weather when temperatures range from 60 to 85 degrees Fahrenheit. Moreover, poorly drained soils, high nitrogen levels, and low mowing heights can increase the risk of fungal development.

Identifying Symptoms of Dollar Spot Fungus

The first sign of dollar spot fungus is small, circular straw-colored patches about the size of a silver dollar. The patches can range from a few inches to several feet in diameter and may appear scattered throughout the lawn or in clusters. As the disease progresses, the patches turn brown or tan and join together to form larger irregularly shaped dead areas. Additionally, the grass blades may develop a bleached appearance, split ends, and pinkish-red lesions.

Preventing Dollar Spot Fungus

While it's challenging to eliminate the fungus entirely, there are some preventative measures you can take to reduce the risk of an outbreak:

• Ensure proper soil drainage by aerating your lawn regularly and avoiding overwatering.
• Maintain a healthy lawn by fertilizing it sparingly and mowing it at the recommended height for your grass type.
• Avoid watering your lawn during late afternoon and early evening as these are the ideal times for the fungus to grow.
• Minimize shade by trimming trees and shrubs around your lawn frequently.
• Use fungicides on a preventative basis during favorable conditions and follow the label instructions carefully.

Treating Dollar Spot Fungus

If your lawn already has dollar spot fungus, there are several treatments available to control it:

• Remove any infected grass and debris from your lawn and dispose of them properly.
• Aerate your lawn to improve soil drainage.
• Fertilize your lawn with a slow-release nitrogen fertilizer to stimulate new growth.
• Apply a fungicide according to the label instructions. Some effective fungicides include propiconazole, chlorothalonil, and thiophanate-methyl.
• Re-seed bare spots with a suitable grass variety for your region.

Overall, dollar spot fungus is a common fungal infection that can affect any lawn, especially during favorable conditions. The key to preventing and treating the fungus is maintaining a healthy lawn and following proper cultural practices. By taking care of your lawn, you can minimize the risk of an outbreak and enjoy a lush, green lawn all year round.

Figure 1. Small circular patches of dead grass on a lawn.

Figure 2. A man aerating his lawn.

larvae, turfgrass, lawn maintenance, organic matter, nutrient deficiency, preventive measures, soil pH, rhizosphere, microbial diversity