How to Manage Pests

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.

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