Seeing unusual growths on your trees? Learn what oak tree galls look like, what causes them and how to manage them with expert advice.
Oak Tree Galls: Can My Tree Be Saved?
Galls on Oak Trees
“What is causing these lumps (above) on my live oaks?” asks Birds & Blooms reader Katherine Gerritsen of Grand Cane, Louisiana.
Horticultural expert Melinda Myers says, “Abnormal growths on a variety of plants, including these, are known as galls. Most galls result from insects feeding, which stimulates the unique growths that can be found in a variety of shapes, textures and even colors. The insect spends some part of its life inside the gall, protected from weather, predators and chemicals. Most galls only cause cosmetic damage and do not require control.
The horned and hornless stem oak tree galls, however, can eventually girdle the stems and cause twig dieback. No chemical control has been found effective. To avoid severe dieback, removing all the twig galls in the first winter they appear is recommended.”
Psst–this is why you need an oak tree in your backyard.
Cherry Tree With Galls
“The leaves on my wild cherry trees are growing smaller leaves right from their surfaces. What is going on?” asks reader Sybil Collins of Hemingway, South Carolina.
Melinda says, “Bizarre growths, called galls, can be found on cherries, maples, oaks, hackberries and many other plants. The growths are actually part of the plant. As certain insects such as mites, aphids and adelgids feed, the plant responds by forming growths around the insect. These types of galls are not harmful and no treatment is needed. In fact, when you notice the problem, the insect is usually tucked safely inside the growth.”
Backyard tip: Easily ID a cherry tree by looking at the bark. On a mature cherry, it’s shiny and looks almost burnt. It also has noticeable lenticels, which are scattered horizontal marks that are a shade lighter or darker than the rest of the bark.
Next, learn how to treat and prevent apple scab disease on your fruit trees.
About the Expert
Melinda Myers is the official gardening expert for Birds & Blooms. She is a TV/radio host, author and columnist who has written more than 20 gardening books. Melinda earned a master’s degree in horticulture from the University of Wisconsin-Madison.
Sources
- Wisconsin Horticulture Division of Extension – “Deciduous Tree Galls“
