Picea sp.

Description:

This spruce tree is located near the Southeast corner of the James Murray Building on the Old College campus in Olds, Alberta. It shares a bed with several other species of tree and shrub and appears to be an older specimen. Though many of the branches appear normal, as seen in the first photograph, there are large branches throughout the tree, in no apparent order, have lost their needles and appear to be dead or dying. Upon closer inspection of one of these atypical branches lower to the ground, a canker could be easily seen. This canker appears oblong, sunken, and oozing with a collar of grey/blue/white growth around the wound. The resin that is is oozing appears clear on the wound site, and white as it moves and dries.As seen in the third picture, smaller but similar patches of grey/blue/white growths can be seen further down the same branch. These cankers may be caused by a species cytospora fungi.

Habitat:

As described by Colorado State University, Cytospora cankers can be caused by a number of Cytospora fungi species which typically attack trees in the fall or winter. Cytospora fungi are especially successful infecting trees that are under stress and affected by drought. Since this tree is surrounded by the botanic garden and sitting near an open parking lot, it is quite exposed to the elements which may have put undue stress on the tree. In conjuncture with this, the drought of the past season may have compounded the stress, allowing disease to set into its weakened host.

Notes:

In order to prevent the Cytospora fungi from killing the tree, Colorado State University suggests that all infected branches be pruned out and disposed of, and all of the wounds left from pruning be treated with a fungicide to prevent further infection. In addition to this, because this fungi typically affects hosts that have been weakened due to other stressors, preventative measures that reduce stress on the tree can be employed to decrease the likelihood of an infection. Some of these strategies include but are not limited to: avoiding unnecessary wounding to the tree (such as those from mowing or pruning), maintaining appropriate water and nutrient levels, or keeping pest populations under control.