The dieback of Lombardy poplar, so noticeable along roadways and windbreaks, is caused by the canker fungi Dothichiza populea and Cytospora chrysosperma.
Symptoms are typical for a severe dieback.
Dead branches are scattered through the canopy, particularly in the upper branches. Closely examining a dead branch reveals that cankers have girdled the branches. The cankers are oval, sunken areas surrounded by callus. Dead bark may cover the canker, or it may peel back to reveal deadwood. As the tree continues to decline, it may produce sprouts from the trunk.