Dollar Spot in Tulsa Lawns
Don’t you hate it when you get brown spots in your lawn? The problem with brown spots is that it could be any number of things. Correctly diagnosing the problem is the key to fixing it!
Dollar spot is a fungal disease that can affect all kinds of grasses worldwide. Although symptoms may appear slightly different on different grasses or with varying degrees of maintenance, the most characteristic symptoms are the small, circular straw-colored spots. If left untreated, the small spots may coalesce into larger spots.
Identifying dollar spot: If you look at the individual leaves (grass blades) you will first see pale green or pale yellow spots that gradually look water-soaked, and then turn a bleached-out straw color. However, around the lesion will be a dark brown outline, which may be the best way to identify the disease. Often, it is confused with brown patch disease (also called zoysia patch or large patch.) In the morning, when there is still dew on the grass you can see a white cottony growth (pictured below, courtesy of University of Massachusetts Amherst,) which quickly disappears when the grass dries off.
Penn State's website has a great series of dollar spot pictures, taken by John E. Kaminski.
Dollar spot usually develops when weather conditions are right – warm weather in the day, cool nights, high humidity and lots of dew forming on the grass, keeping it moist. This makes yet another argument for NOT watering in late afternoon or in the evening. (See our watering page for proper watering methods.) Extended periods of overcast skies and wet weather can lead to large outbreaks. Drought stressed turf is usually affected more severely. Dollar Spot is most prevalent from late spring to early fall, and it will remain active until the “ideal” weather conditions subside. The greatest activity occurs when temps are between 60⁰ and 70⁰, but infection can occur between 50⁰ and 90⁰. Temps over 90⁰ in daytime, however, will usually slow or stop the infection.
Dollar spot survives the winter as dormant mycelium – mycelium is a network of fine white threads, which is the vegetative (growth & reproductive) part of a fungus. Most fungi, like mushrooms, propagate by releasing spores, but Dollar Spot very rarely produces spores, and not in the U.S. at all. Dollar Spot is predominantly spread by lawnmowers, people or animals walking through the grass, rain, wind, and water. Therefore, it is very important to identify a disease in your lawn before you spread it by mowing and walking through it. This is true for other lawn diseases, as well.
Few fungicide treatments are available to the homeowner to prevent dollar spot. Although more are available to professional turfgrass managers, dollar spot develops a resistance to fungicides, and one needs to try different products and keep switching them. Maintaining a medium to high nitrogen level (appropriate for your type of grass) helps immensely.
For more detailed information, the following websites have great articles on Dollar Spot, as well as numerous pictures.
Dollar Spot of Turfgrass by Oklahoma State University Cooperative Extension
Dollar Spot of Turfgrass in the Home Landscape by University of Arkansas