Petri dishes and bags of bioluminescent fungi glowing in the lab. Armillaria and Panellus are two fungi that have mycelium that glows in the dark.
A pine board with white pocket rot. These interesting white rot fungi have the ability to selectively degrade lignin leaving cellulose behind. Some fungi, such as Porodaedalea (Phellinus) pini, produce small spindle-shaped white pockets while some other white pocket rot fungi produce much larger zones of delignification.
Blue stain fungi impart dark discoloration to wood from their pigmented hyphae. Blue stain can lower the quality of wood used for wood products but in some cases, such as this turned pine bowl, it can add value.
Zone lines or pseudosclerotial plates are made up of fungal melanin that acts to separate incompatible white rot fungi from each other. Often called spalted wood, it is used by woodworkers and artists to make interesting objects.
Aecia on the bottom surface of a hawthorn leaf caused by Cedar-Hawthorn Rust, Gymnosporangium globosum.
Telia emerging from the branches of Juniper Broom Rust in the spring caused by Gymnosporangium nidus-avis
Cone rust affects southern pines and the entire infected cone becomes a site for production of aeciospores. These spores infect the alternate host, evergreen oaks.
Pine oak gall rust with aecia producing aeciospores.
Aecia of white pine blister rust on an infected white pine. The aecial stage is only seen in a 1-2 week period around the beginning of June. This blister-like aecia give the disease its name "blister rust".
Lophodermium has long, thread-like ascospores with a sticky sheath that helps adhere them to needles after they are ejected out of the hysterothecium.
Lophodermium on old pines needles showing the black hysterothecia. These open producing ascospores from the compressed apothecium that is under the black stromatic material.
A red oak infected with oak wilt the previous year will produce oak wilt mats under the bark. In spring, the pressure pads break open the bark and the aromatic fungus attracts Nitidulid beetles. The photo shows the pressure pads of the fungal mat when the bark was removed. These mats would be filled with conidia and if both mating types are present, perithecia will form.
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.
Have you seen the inside of a tree with a large Eutypella canker? This cross section of a tree through the canker shows many years of reaction wood forming in the tree. Photo by Matt Kasson.
There are many different types of canker fungi and many have not been studied. Here are interesting perennial cankers on Madrone from Arizona
What fungus do you think caused this type of canker on this ash tree?
This home owner asks "Is my tree going to die?" Maple anthracnose can cause problems in the spring and early summer. Will his maple tree die?
Spring infection of oak with oak anthracnose can mimic the symptoms of oak wilt. However, there are ways to differentiate oak wilt from oak anthracnose. Can you determine this?
Tree wrapped with heavy twine to prevent winter sunscald. This is a method used in China. Apparently it is effective but very labor intensive to put on and take off each year.
There are many different types of abiotic or non-infectious agents causing tree problems. This pin oak is located in downtown St Paul. What is causing this tree to decline?
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. Watch this page for new photos each week.