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From the Diagnostics Lab: Patchy Lawns Could be on the Way

By Jeff Cole, Colorado Master Gardener

It was no surprise that most lawns looked great because of the spring precipitation. However, with the heat and dry weather earlier this month, some lawn problems have started to appear. Did you know that the vast majority of turf problems are due to improper irrigation? June was blistering and there was no end in sight until recently. As a result, many lawns have become “patchy.” There are many possibilities for patchy lawns, but there are two common issues.


This doesn’t necessarily mean that sprinklers are not running enough but it can mean that there is possibly a bad sprinkler head or a head in need of adjustment. Maybe the head is broken or maybe it is not covering enough area. To diagnose the problem, perform a simple test by poking a long, narrow flat head screwdriver into the turf. Compare the results in the patchy area to the healthy area. If it is difficult to penetrate the turf in the unhealthy area, this indicates that the soil is very dry and there is probably a sprinkler coverage problem.  

Ascochyta Leaf Blight

Ascochyta is a fungus that shows up after a cool, moist spring followed by drought. Sound familiar? Symptoms may appear rapidly, giving turf a patchy, straw colored appearance. The good news is that Ascochyta only affects the blades of the turf and is not fatal to the turf plant. You may be thinking that since Ascochyta is a fungus, there must be a fungicide to eliminate it. Actually, the best defense against Ascochyta is good cultural management of your turf. This includes proper watering, fertilizing, aeration and proper mowing height. See this comprehensive fact sheet on lawn care for information on preventing common lawn problems.

There could be other possible lawn problems presenting themselves as summer unfolds. We can help. If you would like more information on lawn care or if you have a question about another landscape topic, Master Gardener volunteers are available. Call 303.730.1920 or email the volunteers at Send us a detailed description of the problem along with photos. Close-up photos and photos that show the plant in the landscape are most helpful.

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