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Heat and rain can cause fungus in lawns

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Summer splendor in the grass is being replaced by a fungus among us for some gardeners. I have seen some weird stuff out in the pastures this last week, likely due to the heat and rain. Mostly people like to blame dead patches in the lawn on grubs but often fungal diseases are the culprit and the weather and our own maintenance habits contribute to the problem.  
Despite the advice that fall is better than spring when it comes to fertilization many people still do it which causes problems this time of the year. For example, too much nitrogen applied in the spring of the year is linked to a higher incidence of fungal diseases like red thread, dollar spot, frog-eye and brown patch. Add weather extremes, automatic sprinklers, mowing habits and susceptible turf varieties and we see odd things happening to our late summer lawns.
Dollar spot is caused by a fungus that is favored by temperatures between 60 and 80 degrees and prolonged moisture. It is most prevalent on bentgrass (which is primarily used on golf courses around here), bluegrass and fine fescue lawns. Yellow spots first appear on the blades of grass and advances to a reddish-brown color; the tips remain green. As the grass dies it typically forms dead patches that are about the size of a silver dollar, thus the name dollar spot. Use tall type fescue and don’t over fertilize or over irrigate your lawn and you should avoid this lawn disease.
Brown patch is likely more mainstream when it comes to lawn diseases because it will impact tall fescue (the best and predominate grass for our area). The disease is caused by a common soil fungus that is favored by too much nitrogen, humidity and temperatures between 60 and 85 degrees. It appears as an overall deterioration of sections of turf; and irregular or circular brown patches. The turf will look pale green and usually there is a brown border around the infected area.
Brown patch can be discouraged by applying nitrogen in the fall of the year only, mowing a bit shorter than the recommended 3 inches (try 2 ? instead), and irrigating only when needed and in the morning so the grass can dry during the day.
Red thread looks like red thread, really. A reddish-coral color fungus appears in strands and eventually causes the decline of grass blades. This fungal disease is most prevalent during wet, cool weather and in lawns that are deficient in nitrogen. Red thread may have shown up a few weeks ago for some during the cool, wet weather variables.
Frog-eye, or fusarium blight, is so named because in the later stages of the disease the center of the infected area remains viable and the dead grass lies in a 2-inch wide band around the green center which sort of looks like a big frog eye. We see frog-eye during the hottest and most humid Kentuckiana summers. Too much nitrogen and drought stress help the fungus along, too. Bentgrass, bluegrass and red fescue are most susceptible.  
Fungicide use to control these problems is tricky because once the problem is apparent it is essentially too late to control. Applications must be used as a prevention, which is not recommended for the average homeowner. We cannot control the weather but we can control our management habits. Don’t fertilize in the spring, irrigate only when necessary, mow when needed and at the proper mowing height (2 ? to 3 inches), and sod or seed with recommended tall type fescue varieties. And, if you did get a lawn fungus send the kids out to do a science experiment instead.