Answer: Based on your description it sounds like a disease problem. I would suggest you contact your local county extension to obtain a specific diagnosis of the problem and based on knowing that, determine how to treat it. If a chemical control is needed, they will have the most up to date information on what to use and how/when is best to apply it for maximum results. In the meantime, you may find the following information interesting, it also includes contact information for your local office:
I hope it is nothing too serious.
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