Fusarium Canker

Fusarium canker appears as sunken, discolored lesions along stems and branches, typically on Laburnum, black locust, and sophora species. The bark becomes rough and cracked over the canker, and branches above the lesion may wilt or die back gradually. Cankers expand slowly over multiple seasons, and secondary insects and decay organisms often colonize the damaged wood.

This canker fungus exploits stressed or wounded trees, so prevention centers on maintaining plant vigor and minimizing branch damage. Avoid pruning unnecessarily, and if you must prune, do so during dry conditions to allow rapid wound closure. Remove heavily cankered limbs entirely; the disease seldom clears once established in major branches. Plant selection matters: choose healthy nursery stock and site trees with good drainage and adequate air circulation.