Verticillium Wilt
Leaf symptoms
Vascular discoloration may appear greenish - grey
Vascular discoloration in cross sections of maple branches.
Microsclerotia (dark round structures in micrograph) are formed by the fungus. These are masses of thick-walled mycelium that allow the fungus to survive long periods of adverse conditions.
A higher magnification view of the microsclerotia.
Conidia are also produced. The conidiophores are whorled with conidia produced on the conidiophores. No sexual state is known.