Photo of the Week

Fusiform rust aecia

Aecia of fusiform rust on the main stem of young slash pine in northern Florida. Aeciospores infect red oak leaves in spring (February/ March).

White pine blister rust aecia

Aecia of white pine blister rust form on the edges of the infected area in spring (late May / early June in Minnesota). Aeciospores infect Ribes.

Brown spot

Brown spot caused by Mycosphaerella dearnessii (Lecanosticta acicola) on longleaf pine

Oak wilt mats

Oak wilt mat produced on a red oak under the bark. In spring, the pressure pads break open the bark and the aromatic fungus attracts Nitidulid beetles. 

DED Campus BeforeDED Campus After

The University of Minnesota Saint Paul campus looking toward the student center from Cleveland Ave before (left) and after (right) large losses of elms from Dutch elm disease.

Canker on tree

What type of canker do you think is on this ash tree?

Maple anthracnose

This homeowner is very worried about his tree. He asks "Will my maple tree die?" This is maple anthracnose and while leaves can be severely affected when we have a wet spring - the tree will not die.

Anthracnose on oak

Oak anthracnose is a leaf disease but can mimic the symptoms of oak wilt.

Tree wrapped for winter sunscald in China

To protect thin barked trees planted in China from winter sunscald trees are carefully wrapped with thick twine.

SO2 damage on birch leaf

Some symptoms of air pollution can be very distinctive such as this damage on birch due to SO2

red pine trees

Keeping forest and urban landscape trees healthy requires a good knowledge of tree diseases. This class will provide you with important information you can use in the future.