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I have small fleshy white things growing on the outside of my azalea bush branches. Is this a fungus? What shall I do? April B., Groton


I have small fleshy white things growing on the outside of my azalea bush branches. Is this a fungus? What shall I do? April B., Groton Actually, what you are seeing is called an "Azalea Leaf Gall" which is caused by a fungus, Exobasidium vaccinii. "Azalea leaf gall" is quite common and first shows up in early spring on new azalea growth and causes the leaves to become distorted and thickened. It is not well understood how the fungus penetrates the growing tissue of azaleas and causes the abnormal growths, but it is likely due to the interaction of hormones and other chemicals. The fungus has a layer of cells called the "hymenium" which contains spore-bearing cells; as the spores get scattered in the wind, the fungus spreads. The azalea leaf gall growths start out as light green and can change to pink, white and then brown before they harden and fall off the plant. Sometimes they can also develop a black coating. Most often galls will show up on the lower leaves of azaleas, but if the weather is humid, you may see them on the upper branches as well. You generally see Azalea Leaf Gall more in the spring or early summer if the weather has been cool and moist.

The good news is that although Azalea Leaf Gall looks awful, it doesn't generally damage the azalea and can be easily removed. When you first spot it, carefully prune off the affected branches, bag them and put them in the trash to be taken to the incinerator. As you are pruning, disinfect your pruners with rubbing alcohol so the infection is not spread to other parts of the azalea. After you prune the gall out, it's a good idea to add a fresh layer of mulch under the azalea to bury the spores so they don't re-infect the plant. Most often azalea leaf gall doesn't become an annual problem, but be vigilant and prune them out if you see them.

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About Linda Lillie

Linda K. Lillie is the President of Sprigs & Twigs, Inc, the premier landscape design and maintenance, tree care, lawn care, stonework, and carpentry service provider in southeastern Connecticut since 1997. She is a graduate of Connecticut College in Botany, a Connecticut Master Gardener and a national award winning landscape designer for her landscape design and landscape installation work.


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