That could be due to damage from a weed and feed fertilizer used nearby. Or it may be due to soggy wet, poorly drained, soil conditions. I suggest you dig down a few inches and feel the soil to see if it is saturated or not. My only other suggestion is to take a sample from the plant or some closeup photos and a distant photo to your County Extension Office to see if they can diagnose it for you with a visual in hand.
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