What are treatment options for this disease?

If this is a first time occurence proper irrigation and fertilization should remedy the problem.  If this is a recurring problem then a chemical will need to be applied. 

For the homeowner Ferti-lome Liquid Systemic Fungicide is a good option for treatment.  It will take a couple of applications seperated by 14 days.  Always read the label through and follow directions carefull to safegaurd yourself and the plants your treating.