Question
I am growing herbs indoors for a class project and it seems my rosemary has a rather bad case of powdery mildew. The mildew is all over the plant so I can't just remove the infected parts. It is also planted in  a window box next to thyme and oregano and cinnamon basil. How can I get rid of it on my rosemary and keep it from spreading to the others? (Oh, weather wise I live in southern California)

Answer
Since you are probably gonna want to eat this stuff, you are limited in your treatment options.  I would mix one tablespoon of baking soda and one tablespoon of cooking oil (wesson) in a gallon of water.  Calculate this down for a smaller spray bottle you have around the house.  This is called the Cornell Fungicide.  Spray the plant every 3-4 days with a fresh mixture of this concoction.  It should slow the mildew growth and allow the new growth to come out and remain healthy.  It will not kill the mildew and it will not go away forever, but you should be able to get some healthy sprigs to cook with by using this meathod.  By the way---you can eat the mildew affected leaves as the fungus will not harm you either. Good Luck.