Our world will never be without horsetail, so why not put it to good use?  Prevent rose diseases, mildew and rust with this horsetail infusion.  This weed that lasts till the end of time (Equisetum arvensis) contains calcium, iron, magnesium, molybdenum, potassium and sulfur.  Good stuff for a foliar spray.  Dry horsetail plants, crush them and store in an airtight container.  To prepare horsetail infusion, simmer 1 pound of dried horsetail leaves in 1 gallon of rainwater or distilled water over low heat for an hour.  Allow the liquid to cool for 12 hours or overnight.  Filter and dilute it to a 20 percent solution.  Use as a foliar spray weekly on roses early in the morning.  (From the book Growing Roses Organically by Barbara Wilde.)