What are the brown spots on my lawn?

We’re receiving many calls regarding brown patches in lawns. Many are concerned their lawn is burnt or puzzled as to why their lawn has it, and they’ve never noticed this type of symptom before.

Look at the photos below to decide if you are experiencing the same symptoms on sections of your lawn.

This problem illustrated below; we identified as Ascochyta leaf blight. Ascochyta leaf blight causes large irregular patches of turf to turn straw-brown and appear dead quickly. From a distance, the symptoms resemble drought stress. The difference is Ascochyta may appear quickly or overnight. Infected leaves present bleached tip dieback, and the margin between healthy and disease shows a slightly pinched appearance. Some leaves may have uniform lesions that affect the entire leaf blade. Mostly, you will notice the blade tips will be brown/dead looking, and as you follow down, the green stalk tissue will be present. It’s almost as if the lawn was cut with a dull mower blade. However, the length of the brown section typically is far greater than what you would usually notice after a rough cut.

Areas, where the subsoil is a gravel or sand base, will typically illustrate this appearance more than other areas that contain a higher amount of organic matter.

It was just a few weeks ago that we were experiencing 40-degree daytime temperatures, and then we had a few days that spiked above 80 degrees. However, the evenings were very cool. This rapid change in weather conditions with such dramatic fluctuations of temperature is perfect conditions for disease to bloom. The good news is most lawns and areas that illustrate these symptoms will recover. Now that we are in a period of drought stress, these symptoms appear worse.

Management


Maintain a higher mow height. We recommend 2.5″ – 3″ normally. When heat and drought are present, we suggest holding off on mowing or cutting at a higher level. 4″ would be adequate. It is essential to mow with a sharp mower blade. It would be best if you sharpened your blades AT LEAST once per year. We recommend once in the spring and once around late August. Landscapers who mow properties daily should be sharpening daily or weekly.

Irrigating these areas is essential for recovery. The goal is to “GROW” the grass out of the problem. You cannot expect grass to grow if it doesn’t have water. The good news is you don’t need to water every day, and you don’t need to water the areas that are already green and appear to be growing. Focus on the brown stressed regions and saturate the soil. Using a sprinkler for 2 – 3 hrs in each of these areas to ensure enough water reaches deep enough into the ground to the base of the root systems. Typically this ranges (depending on your standard mow height) around 2.5″-3″. If you mow consistently shorter such as 1.5,” you can expect your root systems to be approximately 1.5″ in depth. Once these areas can rehydrate, they will begin growing again, pushing new shoots and allowing you to mow off the brown tips and return your lawn to the color you had earlier this season.

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