I think this is a clear case for buying some Phyton 27 (don't confuse it with Physan 20, which is not systemic). Phyton 27 is expensive, I bought mine at Hummert Int. It was $53 for 8 oz. I see they now have a 2 oz bottle for about $20, but they have a minimum order of $50, so you can look else where or buy the larger size or add in something else.
Phyton 27 is systemic for both fungal and bacterial diseases. It is the best thing out there that I know of and it works. In your case it will be worth the cost.
http://www.hummert.com/catalog.asp?C=65&SC=2&P=507