Answer: I'd cut off the affected leaves. Leaves can develop brown margins if they get too much sun or are near a lawn that is regularly fertilized (nitrogen burn). However, there are other possible causes: if the spots are random and tan to brown, it could be fungal leaf spot. Remove severely infected leaves, and minimize wet foliage. If the spots are brown and clustered, it could be damage from the Four-lined plant bug. If the leaves are mottled (called ringspots), it might be a Mottling Deformity Virus. Laboratory identification is needed to determine which type of virus, and management strategy.
Hope this information helps!
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