Dollar Spot Disease

Summer weather provides a host of environmental stresses to the cool-season turf varieties that we have in New Jersey. Temperature, humidity, lack of rain, and sometimes too much rain all impact residential lawns throughout the summer months. Outside of heat stress, foliar diseases are a common issue we encounter as lawn care professionals. One of the most frequent diseases we see in the summer months is Dollar Spot.

Appearance

As I mentioned briefly, Dollar Spot is a foliar disease affecting the leaf tissue of grass blades. You can imagine because of the name; the most notable trait of this disease is its appearance. In the image below, the disease presents as burned or bleached circles in the lawn that resemble silver dollars. These circle-like shapes can continue to grow and morph into bigger areas that then no longer resemble small circles.

Causes of the Disease

If this disease is so common, what is the reason it is in your lawn? Well, unfortunately for the homeowner, certain grass varieties are more susceptible to this disease.  We commonly find dollar spot on fine fescues, especially when these shade loving varieties are planted directly in the sun.  Using generic sun and shade mixes when homeowners seed is usually the main culprit of having turf that prefers the shade growing in the full sun. Other varieties like rye grass, blue grass, and even tall fescue are also susceptible.

Secondly, weather conditions also play a large part of when this disease becomes active. Most foliar diseases we encounter in the summer months like hot, humid, and wet weather. This means, nighttime temperatures above 55 and daytime temperatures in the 80’s-90’s. The main component however is moisture, the turf blades must be wet for dollar spot to infect the plant. Some recent summers in New Jersey, we have experienced a great increase in rainfall, while others are more notably remembered for a drought.

The moisture component is not just left to mother nature, we can be promoting disease by watering too frequently.  Remember, the grass blades must be wet for the disease to infect the plant, so having your sprinkler set to water every day increases the likelihood of disease. Long periods of leaf wetness from dew, rain, or sprinkler irrigation, coupled with warm temperatures, leads to the perfect environment for dollar spot to start spreading. We will discuss proper watering a little later in this blog.

What do you do once your lawn has dollar spot disease? There are two areas of control that we should discuss: chemical and cultural.

Dollar Spot Treatment

From the chemical side of things, you can apply a foliar fungicide to your lawn to help stop the spread of the disease for 20-28 days. With the appropriate use of fertilizer and irrigation, you can start to grow out the turf and you will see the diseased tissue going away with mowing. Something very important to remember, a fungicide applied to the lawn after the disease is present will NOT make the disease go away. The fungicide only stops the spread of the disease for a period of about a month. An additional fungicide may need to be applied if favorable weather conditions continue.

If you are reading this blog because you have dollar spot disease in your lawn every summer, then a preventable fungicide program may be the solution you are looking for. If you apply a foliar fungicide to the lawn before the disease is active, you can prevent disease activity on the property for about a month. Talk to your lawn care professional to see if you should be applying fungicides preventatively, and depending on your property, what months they recommend. For people in our service area, we normally recommend a monthly fungicide applied from June through August.

Cultural Considerations

We touched on how most diseases need the presence of prolonged wet foliage. For homeowners that have irrigation or hose-end sprinklers; there is a way to reduce the amount of time your grass blades stay wet. Changing your watering schedule from running your sprinklers every day for twenty minutes, to DEEP and INFREQUENT watering. This means only water every third or fourth day for an hour to an hour and a half per zone. The goal is to provide your lawn with an inch of water every week while letting the grass blades dry out in between watering. The best time to water is between midnight and 6am, this is because the grass is already wet from dew formation so we are not prolonging the time it stays wet.  For more information about a watering schedule, please visit our blog.

Additionally, we would also recommend adding aeration to your lawn care maintenance schedule at least every other year. Decreasing soil compaction and thatch improves water and nutrient flow deeper into the soil which leads to root growth. Healthier grass plants = more stress tolerant.

Finally, if your property is largely a grass variety that is more susceptible to Dollar Spot disease, you can overseed your lawn annually with a more tolerant grass type. We would recommend using the right variety for the area you plan on seeding.  We like turf type tall fescue, Kentucky bluegrass and annual ryegrass in areas that get a lot of sun and fine fescues in areas that are shaded.  If you plan to go down the route of overseeding your lawn and you are in our service area, feel free to reach out to our office and we can help answer any questions.

Conclusion

Dollar Spot disease is a common disease in the New Jersey area during the summer months. While it is common, there are a couple of steps you can take to reduce the damage of the disease both culturally through your watering methods, and chemically with fungicides and adequate fertilization.

If you have questions about Dollar Spot disease, feel free to reach out to our office to speak with a lawn care professional, at 908-281-7888.