If you want to go with synthetic chemicals and are not concerned about residual toxicity, look for thiomyl - it's the generic version of Cleary's 3336. Use at 1 tablespoon/gallon.
If you want to go with an ecologically friendlier approach, Concentric Ag's Inocucor Garden Solution is the way to go. It consists of several, cooperating consortia of beneficial bacteria and fungi that "infect" the plant and any medium, killing the pathogens, secreting antibiotics to reduce or prevent future infections, and secreting plant growth stimulating hormones, to boot. 3 Tablespoons per gallon, thoroughly wetting the plant, roots and medium. Reinforce that daily for 2-3 days, then after that, use it once a month as a probiotic/preventive treatment.