Friday, October 28, 2011

End of the Season, "My Spruce is Dying" -Cytospora Canker

The U of I Plant Clinic has been receiving calls and samples from clients because their spruce is dying.  We received one sample that consisted of just spruce branches.  There were no signs of disease on these branches.  Unfortunately, there were no needles included with the sample, but the client did include a CD with several pictures.  I called him to get further information on what may be going on with his trees.  On the phone, he said that some of his spruces were dying and he was afraid that whatever was killing them might spread to his other trees.  He continued to tell me he had a row of spruces on his property that were 15 to 20 years old.  One of the spruces had already died.  Travis Cleveland, U of I Extension, PSEP (also an urban tree expert) and I both examined his pictures, which were included with his sample.  I suspected Cytospora canker and Travis suspected an injury at the base of the tree.  I told the client to please check for "oozing cankers" or white sap on the trunks or the branches of his spruce trees, because this is a sign of a fungal disease called, Cytospora canker.  In addition, I wanted him to check for any possible injury at the base of his trees. 

Here are the pictures he later sent to me via email:

Note the twine/plastic girdling the base of the tree.

As it turns out, Travis and I both were correct.  A few trees that had been described by the client as "runts" or smaller trees had twine/plastic left on the base of the tree when planted.  As these trees grew, the twine/plastic girdled the base of the spruce, causing tree death.  Other trees did not have an injury at the base, but must have been stressed, because they were clearly infected with Cytospora canker.  You can see in these pictures where the white sap is running out cankered areas on the trunk.  These oozing cankers are sometimes confused with bird droppings.  Some things that may have stressed these trees: heat, drought, clay soils, ????  If branches are infected with Cytospora canker, they may die, and you can trim/destroy them.  However, if the trunk of the tree becomes infected with Cytospora canker...... that can be bad news!  Cankers on the trunk/stem of a spruce can cause tree death.

The Cytospora fungus invades weakened or stressed wood. We can't always determine the cause of stress from the lab, but any site or environmental conditions that are not good for the species could be the actual cause of the problem. Spruces do not do well in hot, dry, poorly drained soil with high clay content. Sometimes problems do not develop on spruce until roots outgrow the area, grow into poor soil, or until weather stress aggravates the situation. Fungicides are not effective. You need to help tree vitality by pruning out dead wood now, watering in periods of drought lasting two weeks, and fertilizing in the fall or early spring with a balanced tree fertilizer. If you can determine the cause of stress, of course, correct that as well. A fact sheet on Cytospora Canker of spruce can be found at the following link:
Cytospora Canker