Issue 10, June 25, 2012

"My Spruce is Dying"--Cytospora Canker

The U of I Plant Clinic has been receiving calls and samples from clients because their spruce trees are declining and dying. Many of samples were suspected or found to be infected with Rhizosphaera needle cast, Stigmina needle blight, environmental problems, and spruce spider mites. One sample we received consisted of spruce branches without needles. We examined the branches, and found no signs of disease. Without needles, we were unable to check for needle blights. The client did provide several helpful pictures to help with the diagnosis.

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 some of the pictures he later sent via email:

Sap running from a suspected Cytospora canker on the trunk of the tree.

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 may have been stressed, and more susceptible to Cytospora canker. 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.

Cytospora canker can be identified where white sap is running out cankered areas on the branches and the trunk. These oozing cankers are sometimes confused with bird droppings. Needles on cankered branches may fade and turn brown during late spring and early summer months. Brown, killed needles may persist into the fall. In most cases, lower branches are infected first and move up the tree from year to year.

Infected branches should be pruned out and destroyed. 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. Unfortunately, fungicides are not effective. You best option is too to help tree vitality by pruning out dead wood, watering in periods of drought lasting two weeks or more, 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. Click here for a fact sheet on Cytospora Canker of Spruce (Adobe PDF) (Stephanie Porter and Travis Cleveland)

Stephanie Porter
Travis Cleveland

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