Fusiform rust

Fusiform rust is a fungal disease that mainly affects pine trees and some hardwoods. It is caused by the fungus Cronartium quercuum and spreads through spores carried by the wind. When a tree is infected, it develops elongated, spindle-shaped cankers on its branches or trunk, which can cause the wood to weaken, scarring, and sometimes killing the tree. The disease can also affect certain oak species, leading to similar cankers. Fusiform rust is a concern for forestry and landscape management because it can reduce tree growth, timber quality, and overall forest health.