Question
I live in seattle, have a greenhouse--Im a beginner--and I have powdery mildew on green bean plants.  they`re not over watered and I`ve increased the ventilation.  I `m also using a spray called serinade, but I don`t want this spreading to the other veggies I`ve got in there--and I think it is.  suggestions???

Answer
Nancy,

I normally don't answer questions about plant diseases (check my profile) so you may want to ask this of someone else. However, I know that powdery mildew is somewhat host plant specific so it may not readily spread to different species. Also, you might look into using some kind of copper spray because if memory serves copper is the treatment for this fungus. Check at Gardens Alive! (google "garden's alive") for their fungicides for use in greenhouses.

Jack DeAngelis, PhD
Extension Entomologist (ret.)
My website about home and garden pests: http://www.livingwithbugs.com