Hosts: Southwestern white pine, limber pine
and ponderosa pine
Figure 218b. Atropellis piniphila symptoms include black-stained wood.Figure 218a. Signs of Atropellis canker include black pimplelike fruiting structures embedded in bark and cup-shaped structures with a chestnut-brown interior that are observable during periods of precipitation.
Symptoms/Signs:
Cankers appear as elongated depressions covered with bark.
Atropellis species produce two kinds of fruit bodies, one flask-shaped
and one cup-shaped, on killed bark. The flask-shaped structure develops
first. These are black, about 1 mm across, and contain multiple
chambers where spores form. The cup-shaped structures are black
with a brown interior, measuring 2-4 mm across when moist. They
form on cankers 2 or more years old and are present year round.
Dark brown mycelium permeates the bark and wood, creating a zone
of bluish black stain that in cross-section is initially wedge shaped,
pointing toward the center of the stem, becoming irregular with
age. Species are separated based on spore morphology.
Biology: Infection begins in a branch axil
on stems 5-30 years old and so there is typically a branch stub
in the center of the canker. Some cankers start on internodes, reflecting
the ability of the fungus to infect wounds or bruised bark as well
as apparently undamaged bark of young stems.
Effects: Atropellis canker can be found
throughout the region but its occurrence is infrequent in natural
forest settings. Although Atropellis rarely kills trees, there are
areas where outbreak levels are reached and mortality occurs in
young trees. It can be damaging in Christmas tree plantations where
it causes trunk deformities and economic loss.
Similar Insects and Diseases: Atropellis
canker may be confused with other canker-causing fungi; however,
Atropellis is the only one that stains the wood.