Text and Photos
By Jeff Burbrink
Ag & Natural Resources Extension Educator,
Purdue Extension LaGrange County

LAGRANGE — About 20 years ago, the number of calls and plant samples concerning Colorado blue spruce increased dramatically in the Extension Office. My clients often describe having several spruce trees in various states of decline and they are desperately seeking a solution to the problem.

As you drive around the area, it is fairly easy to spot spruce trees going through decline, especially on the lower branches. It has even affected two trees on my own property.

The key symptom for spruce decline is branch dieback, usually starting on lower limbs. Over a 4-5-year period of time, needles will drop and the tree will look very thin. In many cases, the plant’s appearance is unacceptable for most homeowners and the tree is eventually removed.

There are multiple issues behind this problem, mostly related to an increase in several diseases that attack spruces.

Rhizosphera needlecast

Needlecast is one of those diseases. Needlecast fungi attack the current year’s needles, but the needles do not fall off until the following season. The result is a tree with an “outer shell” of live needles and dead needles inside. Two diseases cause this problem, rhizosphere and stigmina.

Another disease is tip blight. Tip blight affects the new growth, causing it to die back. Phomopsis and diplodia tip blight are the most common example of this in our area.

Cytospora canker

Another disease, known as cytospora canker, infects branches or the main trunk. The cankers are sunken or ridged areas that ooze resin, which often will turn a white color. As the cankers develop, they can interfere with the trees ability to move water and nutrients and eventually the branch can die.

Why is this happening? Colorado Spruce is native to arid regions in the Rocky Mountains. Our region is much more humid, which is ideal for development of these diseases. In landscapes, spruce are often planted on marginal sites as windbreaks or screens, and as a result, they are stressed and more susceptible to disease.  In other words, spruce are probably not a good plant to use in your landscape in the Midwest. Love will not keep them alive.

What can be done? In most cases, not a whole lot. The fungicides, sprays used for disease control, on the market today are not cures, they prevent a disease from getting established, which means they need to be applied before the plant is sickly. 

In fact, for successful control, the tree must be treated several times a year times and probably over many years as long as the conditions exist that favor the disease. In Indiana, humidity is not going to go away, so we can count on favorable conditions every year. Most of us do not have the financial resources, equipment or time to do this job ourselves, especially on larger trees.

In most cases, the effectiveness of fungicides is limited because the plants have been diseased years before homeowners notice there is an issue. Removing affected branches is a temporary action to improve the trees appearance for a few years and slow the spread of the disease within the tree, but it has little effect on the long-term health of the tree.

Overall, the future does not look promising for the beloved blue spruce in our region, so we really need to think about planting other species. Alternatives to blue spruce in the landscape include the concolor fir, dawn redwood, Serbian Spruce, Swiss stone pine, Korean Pine and Bald Cyprus. Each of these trees has a preferred set of conditions they thrive in, so as you explore your options, be sure to select trees that meet your soil type and conditions.

For more information about the decline of spruce in the Great Lakes area, I suggest reading an excellent publication at https://shorturl.at/glstC from Michigan State Extension, as well as the advice on alternative trees at the end of that webpage.