My 4-year-old wisteria, which grows in a very large pot, has developed lumps on some of the branches. They look like tiny oak apples. Is this a disease?
Certified GKH Gardening Expert
These are called galls and they are like tumors on plants. Sometimes they are benign and only look ugly while other times they can be harmful. Keep an eye on the plant, but if you have not seen any decline in the plant so far, it is likely they are harmless. Here is more information: https://www.gardeningknowhow.com/plant-problems/disease/how-to-fix-crown-gall.htm