Gross. What is on my Azalea?

It is spring, meaning moist and warm. There are many disease pathogens taking advantage of this weather that are affecting plants. One that I have seen on several occasions in the last week attacks azalea. Because we all love the beauty in azalea, this is concerning to say the least.

Picture a fully green branch from an azalea that has produced healthy leaves. Attached to several otherwise healthy leaves appear light green, firm, fleshy blobs. These blobs are fungal growths of Exobasidium vaccinii known as Azalea Leaf Gall.

Often pale green these fungal growths can also be pink and as they mature become white and brown. They may be found on leaves, branch tips, flower parts, and even on seedpods. In late spring or early summer (meaning now) a whitish coating of fungal producing spores will cover the fleshy growth. These spores will move to other plants by wind or splashing rain with the disease becoming more serious as wet weather prevails. Once the spores land on a new leaf they sit and wait to produce fleshy growth next spring. The growth that is being observed now actually infected the plant last summer.

At this time of year the solution to prevent further spread is to hand pick any gall or small leaf that has a fleshy growth and burn it immediately. Once the fleshy growth turns white, it has begun to spread so remove it quickly. Fungicide can be applied but not at this time of year. To help control future growth, fungicide is normally applied just before leaves unfurl in spring with a second application 10 days later. If fleshy growth exists on your azaleas now, then use fungicides next spring. Look for a fungicide with the active ingredient mancozeb and follow the directions on the label.

Most native azalea and rhododendron plants are susceptible with R. maxium and R. catawbiense being most susceptible. With a little elbow grease, you can remove the issue now if you have it, and the azalea should survive.

The Extension office is open Monday - Friday, located in Kennett, Missouri at 233 North Main Street. For horticulture questions contact the horticulture specialist at 573-686-8064. MU is an equal opportunity/ADA institution.