Two people have given you good answers so far. Another step would be to
contact your state cooperative extension service. Google with your state
name and the words "cooperative extension". Or, if you know of a REAL garden
center, call them and ask who to contact. Some CE services are staffed with
retired "master gardeners" who've seen everything over the years. You may be
amazed at the kind of help they can provide, even with just descriptions of
problems over the phone.

Chemicals are absolutely a LAST resort, and a lousy option no matter what.