We have several types of oak trees in our backyard. They have round hard clumps on the braches about the size of golf balls. what is this? is this a dieses?
Visiting Extension Specialist, Forestry
Department of Crop Sciences email@example.com
These large growths on the branches of your oak trees are likely insect "galls". There are many types of galls that affect oak trees and most of these galls are not harmful to the overall health of the tree and as such generally do require any sort of treatment.