Question
I have what appears to be powdery mildew on a rosemary plant.  The plant is in afternoon/evening sun, appears to be growing well, is in a dry climate (Eastern Washington), and the foliage does not get wet when I water.  Any suggested remedies for an organic gardener?

Answer
Thomas:
Powdery mildew on a plant resembles a dusting of baby powder.  Some organic controls include (1) dusting sulfur (pay attention to the outside temperature- hot temps can result in a burn by sulfur), (2)  Products available at garden centers or online ---Milstop or Kaligreeen or Bonide Remedy or Greencure----these are related to baking soda.  (3) various copper containing materials also.

Also be sure to cleanup old dying leaves on the plant and the ones that fall off.  These are good places where the fungus can survive over the winter.

Regards
Steve