Tree Diseases: Crown Gall

Introduction Crown gall is a tree disease of many woody shrubs, and some herbaceous plants. The disease is caused by the bacterium Agrobacterium tumefaciens, a…

Tree Diseases: Dutch Elm Disease

Introduction Dutch elm disease is a fungal infection that affects many species of elm. It is one of the most destructive tree diseases in North…

Tree Diseases: Gall Producers

Gall diseases are common on many trees and shrubs. Galls are abnormal swelling growths that form on the leaves, twigs, branches, roots, and flowers of…