New leaves may be reduced in size and turn yellow. Infected trees may die slowly or suddenly. An olive-green discoloration may develop in the sapwood. Other fungi can also cause this discoloration. The disease does not spread rapidly from tree to tree.
Infection takes place most commonly through the roots because the fungus lives in soil.
Some infections take place above ground through wounds caused by insects or by pruning. Trees showing general wilting of the entire tree cannot be saved. Recently infected trees with only a few wilted branches may possibly be saved by adequate fertilization and watering. It is thought that leaf growth is stimulated, in turn enabling the rapid formation of a thick layer of sapwood, which seals in the infected parts of the trees. Rough, irregular, swollen galls at the base of the trunk or on the roots.