Cytospora is a genus of fungi that primarily affects trees and shrubs, causing a disease known as Cytospora canker. This condition leads to the death of branches and can significantly weaken the host plant. The fungi typically enter through wounds or stressed areas, making healthy plant care essential for prevention. The most common hosts for Cytospora include species like willow, poplar, and spruce. Symptoms often include sunken, discolored areas on the bark, and the presence of resin oozing from the cankers. Effective management includes proper pruning and maintaining plant health to reduce stress.