Dollar Spot Disease

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Dollar Spot Disease

Dollar spot disease is a kind of lawn disease that kills and infects different kinds of grasses. This disease grows in distinct and small circles around the size of a small pancake or a silver dollar. It is easy to take the dollar spots lightly because they do not look dangerous but they can cause serious damage to the lawn.

Dollar spot disease survives during winter in the plant parts in the soil and thatch and it begins to start again as the temperature gets to sixty degrees. Aside from temperature, other factors that cause the disease include low fertility of nitrogen, low moisture in soil when humidity is high, too much mowing during hot climate, and too much thatch. A quality program is needed to provide the lawn proper mixture of fertilizers in order to prevent dollar spot. In addition, lawn should be mowed or watered regularly.

You can identify dollar spot disease in your lawn in two ways. The first way is through the size and shape of the area that is damaged. Usually, individual spots are very distinct and circular in shape, which are only a few inches in diameter. Another sign of dollar spot disease is the appearance of lesions on grasses. The disease can cause bands in hourglass shape across the grass blade, which is light tan in color with a reddish-brown edge. It can kill the entire grass and your lawn needs reseeding or renovation to control the disease.

It is necessary to saturate your soil regularly because grass diseases including the dollar spot occur in soil with low moisture. However, make sure to avoid watering frequently during the late afternoons or evening. Use proper mixture of fertilizers in correcting the nitrogen fertility during the times of the disease activity.

You can apply treatments such as fungicide in getting rid of dollar spot disease. However, fungicide is not required in residential lawns if the levels of nitrogen fertility are managed properly and other cultural stresses are lessened. Dollar spot disease has different degrees of fungicide tolerance and there are some strains of dollar spot that have become resistant to fungicide, so a particular fungicide may be effective to one disease but not to another. In addition, the use of fungicides can increase disease and insect problems in the future because they can affect the soil organisms such as microbes and earthworms, which help in the decomposition of thatch. In addition, earthworms and other soil organisms improve the health of the grass and help aerate the soil.

You need to have a balanced nitrogen fertility program to control the disease because dollar spot disease is known to be most severe on nitrogen-deficient soil. With a balanced nitrogen soil, the outbreak of the disease will be delayed in the spring and the severity of outbreaks will be reduced. In addition, the performance of fungicide will improve and the recovery of turf will be faster.

Proper scheduling of irrigation is necessary to control dollar spot disease. This is due to how fast the period of dew is relative to the infection extent, so the prolonged practice of irrigation will greatly contribute to the outbreaks of the disease.

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  1. Don Oleske

    I’m hoping that someone can take a few moments to answer a few questions I have about Dollar Spot disease.

    First, I live in SE Lower Michigan. I have always taken great pride in my lawn. I only use 12-12-12 fertilizer on the lawn. Nothing else. I apply it 4 times per season. The lawn has few weeds. The few there are, I spot spray. I water at least every other day in the morning. During extreme heat and humidity periods, I water daily. There are typically no periods in which the lawn is allowed to become truly dry.

    I mow once a week at a medium to high blade depth. The lawn is about 12 years old.

    3 years ago, I noticed that beginning in July and during periods of high heat and humidity, I was beginning to see spots on the lawn that I have come to the conclusion are “dollar spots”. The spost seem to fill in well in the Spring. Prior to their first appearance in July, the lawn looks excellent. I have had the problem each year since. They seem to be preceded by what look like patches of webs on the lawn. This year it is particularly bad. The spots seem to be accumulating close to my sidewalk, driveway and street, seemingly where water tends to run off the grass.

    The dollar spot article in your site talks about a possible cause being dry soil. I don’t think this applies here, as I water frequently. I do not thatch my lawn, as I have never found it necessary. Another cause is stated to be low nitrogen levels. This makes me wonder if my prolonged use of 12-12-12 might be part of the problem. Maybe I need to supplement feedings with a fertilizer with a higher nitrogen content? If so, how much and how often?

    The site also indicates the use of a fungicide. Can you recommend a type and brand? Also, when is the best time to use the fungicide and how often?

    I appreciate your time and consideration of this problem. Any suggestions you can provide will be very much appreciated. I know it sounds a bit weird, but this problem is bugging me something fierce. PLEASE HELP!

    Thank you.

  2. Don,

    Thanks for your comment and questions. I have a few recommendations that you might try. Don’t feel like you have to water every day because the article recommends keeping the soil moist. In fact, I would rather you water deep and only as often as your grass seems to need it. Are heavy dews prevalent when you’re having trouble with the spots? If so, you might try dragging a hose (or something like it) across the lawn in the morning to disperse the dew. To increase your nitrogen, I would begin using a 32-0-4 about the time you start to have the problem each year. Another thing you can do is apply a top-dressing of compost over the affected areas. Research has shown that well-aged compost (at least 1 year in age) can effectively muzzle lawn diseases. Apply about a 1/4″ layer of compost every month. You can use a broom or rake to spread it into the grass evenly. This will not only help the disease, but will help break down thatch in your lawn and support greater microbial activity in the lawn. I would try a fungicide only as a last resort if none of the above works. I hope that helps. Good luck!

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