The greatest economic loss results from death of high value urban trees. Identifying the Fungus. In the laboratory the fungus readily produces easily identified, spore bearing structures. Identifying the Injury.
Symptoms normally progress rapidly through the crown.
Complete wilting often occurs within six weeks of infection. Yellow foliage caused by the Dutch elm disease fungus. Generally, death of the infected tree is rapid. However, some asymptomatic trees have been found that had been infected for several growing seasons. The specific manner in which the fungus kills trees is unknown.