I am sorry for this delayed reply to your gardening question. We are transitioning to a new Q&A system and your question was unfortunately lost in the transition. I have discovered it now and hope this reply is not too late to be of help.
If the browning is all over the plant is suffering from a major root problem and will probably not pull out of it. Soggy soil and dry soil both can kill roots. Damage from weed killers including weed and feed products are also a fairly common problem. My best guess without actually seeing the plant is that a period of wet conditions with poor drainage are the killer or perhaps a root rot disease which often follow wet periods.
Thanks for the question. Please stop in again soon!
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