Question From: R. Foote - Whittier, California, United States
Q: I have poppy plants growing in my planter with about 50% sun. The plants all start out good but as they flower the plants leaves & stems start to turn white. I keep them watered well and feed them occasionally. My guess is that it powdery mildew but I am only guessing. Is this possible or might it be something else? Your help will be appreciated.
Your poppies are indeed suffering from powdery mildew. Lack of sun - they are full sun lovers, too much water - and excessive fertilizer are all culprits. As soon as you see the smallest speck of white, spray with a product such as neem oil or Serenade. Serenade is a biological fungicide made from the bacterium Bacillus subtillis. Either product must cover all the leaves and stems, so be sure to spray the backs of the leaves. You will need to re-spray every 7 to 10 days. Once it takes hold, control is difficult and the diseased leaves and stems will never clear up. I suggest you find another annual that will be happier in window box. Take a tour of your local garden center and see what's available in your area. Best And Happy Yardening, Nancy