Spray early in April with a fungicide. Most willow species are highly susceptible. Plants suddenly wilt and die, leaves usually hanging on the plant. Roots will be decayed with the bark peeling off very easily. Wood decay fungi usually enter the tree through wounds.
Most fungi grow rather slowly showing no evidence of being present until extensive areas are rotted.
Most will first invade the non-functional heartwood. After decay is well advanced in the heartwood, they may invade the living sapwood. When the fungus has developed extensively, fungal fruiting structures, commonly called shelf fungi or conks, may appear on the trunk. Some fungi may form mushroom-type structures at the base of the trunk or form on major roots, rather than on the trunk. Where extensive wood rot has already occurred, the rotted wood should be completely removed.