There was such a question on
Ontario Today's call-in gardening show today, and their gardening "guru" said that it was caused by a certain type of aphid. There should be a state agricultural extension service whom you can contact (virtually every state has an agricultural extension service, and it is usually run by state universities' agricultural and/or agronomics departments). This is a "fixable" problem, and i suggest you get in touch with your state's extension service.
