Dealing with white stuff on phlox

Q. My phlox has white stuff all over it, what is it?

A. For masses of color in your flower beds, long-blooming phlox is hard to match. Many varieties are fragrant, make terrific cut flowers, attract butterflies and hummingbirds, and have been a garden favorite for generations. You can find a type of Phlox appropriate for almost any garden position. Spring-blooming creeping Phlox are suitable as groundcovers in rock gardens and in woodland plantings. The garden phlox enlivens the back of the flower borders during the summer months.

Unfortunately, the beauty of phlox often comes with a price; they tend to develop powdery mildew, seen as a white powdery gray coating or fungus growth on the upper leaf surface. This growth begins on the lower leaves and progresses upward to the upper leaves. The warm summer days with high humidity followed by cool nights increases powdery mildew development on the plant. While this condition doesn't kill the plant it does reduce its aesthetic appeal.

To manage the powdery mildew infection, it's advisable to make sure that there is good air circulation within your phlox plants, they should not be planted in shaded or damp corners of the garden and that you should keep your garden clean by removing any fallen and diseased leaves immediately. Make sure to plant them in rich, well-drained soil in full sun. Keep them watered during dry periods Avoid over fertilizing the plants especially with a lot of nitrogen fertilizers and make sure you water the plants early in the morning to ensure that the leaves remain dry during the day. Spraying the plants with organic horticultural oil has been used to control the diseases. However, the best long-term solution is to plant powdery mildew-resistant phlox cultivars. These resistant cultivars include: Phlox paniculata David, Orange Perfection, Prime Minister, Blue Boy and Starfire.