Canker stain (Ceratocystis canker)—Ceratocystis fimbriata
The fungus that causes canker stain is unusual
in that infection almost always is the result of mechanical
injury or wounds caused by people. Canker stain causes sparse foliage and undersized leaves.
Rapid decline and death of the entire tree can occur. Discolored,
elongated wounds or cankers develop on infected limbs and
trunks. Cankers may be
sunken or covered with bark that is off-colored or flaky.
Infected cambium, phloem, and sapwood tissue darkens. Agrobacterium
tumefaciens causes crown gall on fruit trees, evonymus,
rose, willow, and other broadleaf trees and shrubs. Another
bacteria, possibly Agrobacterium pseudotsugae causes
similar bacterial gall on stems of douglas-fir, especially
under wet, stressed conditions.
Solutions
Avoid wounding trees;
don't nick shallow roots with mowers. Fungal
spores readily spread on tools or equipment from one tree
to another and are able to infect only fresh wounds. Tool
sterilants found effective for fire blight can be used to
reduce spread of canker stain.
To prevent spreading pathogens on infected tools, clean off
debris after each use and thoroughly spray them with disinfectant
or soak them in disinfectant for 1 minute or more. Tools
can be sterilized using
a household bleach or commercial disinfectant as directed
on the product label. | 
London plane tree killed by canker stain
|
