Answer: There are many different possible causes depending on where it is occurring and how your lawn has been cared for and its overall health, unfortunately it is impossible to diagnose this type of symptom long distance. I would suggest you work with your local county extension to get a firm diagnosis before trying to treat for it. (It may be something as simple as overfertilizing or drought on thin soil or it could be a pest or disease issue requiring carefully timed applications of a chemical control.) In the meantime, you might find the following troubleshooting list helpful.
Good luck with your lawn!
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