Azalea Diseases: Mildew


One of the reasons that azaleas are so popular in landscaping is that they are so difficult to kill. These hardy plants can take cold, drought and heat and are also resistant to a wide variety of plant diseases and problems. However, a case of mildew will not only mar the beauty of your seasonal flowers; it can also take down your azaleas for good. The best way to deal with mildew and avert infections is to know the signs of the problem long before it is creeping along your flowers and blackening your bushes.


Several types of mildew can infect azaleas. One form rots the roots (root rot), while probably the most easily recognized is powdery mildew. Mildew blight can also impact the leaves, twigs and even the petals of azaleas.


If your azalea is suffering from mildew, you may notice several different symptoms. The most easily recognized mildew is powdery mildew, which creeps along twigs, leaves and branches, leaving its powdery, grainy gray, white or black spores in its wake. However, mildew that has rotted the roots of the plant will simply make the plant appear to be withering due to lack of water, while leaf fall, blackened leaves and twigs and withered, black flowers characterize mildew blights.

Treating the Problem

In most cases, the fastest, most effective treatment for mildew is an application of basic fungicide. Azaleas with mildew are also highly responsive to a healthy coating of jojoba oil. If you catch and treat the mildew quickly, it should not permanently damage the plant. Remove affected twigs using sterile pruning shears. If your azalea has root rot, however, it is probably too late to save the plant. Remove it from the area entirely to prevent the infection from spreading.

Preventing Mildew on Azaleas

Most azalea cultivars are bred to be mildew resistant. However, you can assist them by placing them in full or nearly full sun. Also, water them if the soil is dry, but do not water daily or multiple times throughout the day. Water in the mornings to give the leaves, twigs and flowers all day to dry out, to prevent mold. In addition, make sure that the soil around the plants is well-drained and does not get muddy or sticky when you water.


Mildew can spread from plant to plant very easily. Make sure that you always bag and remove affected parts of the plant rather than dropping them on the ground where the mildew will continue to feed on them and may spread to other plants.

Keywords: azalea mildew, azalea diseases, mildew on azaleas

About this Author

Carole VanSickle has over five years experience working with scientists and creative scholars to promote and explain their work. She is based in Atlanta, Ga., and specializes in scientific, medical and technical writing, SEO and educational content.