A view of a single tar spot. The surface of the tar spot shows a mazelike pattern of ridges and furrows, indicating where the apothecia will develop. The infected fruits are inflated and hollow. In this picture only one of each pair of fruit is infected. Photo courtesy of H. A. Lamey.
Infection occurs during leaf expansion, resulting in the raised blisters.
The small dark spots of elm black leaf spot are slightly raised, giving the surface of the leaf a pebbly feel. These contain the spores. Photo courtesy of H. A. Lamey . These images are provided for the personal use of students, scholars, and the public. Any commercial use or publication of them is strictly prohibited.