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Conifer Madness

Photo by M. Grabowski

When I first started in Extension, I imagined my day would fill with questions about gardens and farm fields. My graduate school research dealt with the prairie, a biome that directly enabled those gardens and fields to be the most productive in the world. I quickly became enamored with grasslands, fascinated with their diversity and soil building abilities. The great conservationist Aldo Leopold once remarked that forest and prairie were in constant battle. My loyalty lied with big bluestem and yellow coneflower, not scrubby oaks and eastern red cedar. Little did I know that my job would largely entail helping prairie’s sworn enemy...

Thirty five to forty percent of my service calls deal with trees, and the vast majority of those calls consist of evergreens that often do not live up to their name. Needles that were sloughing off, browning tips, weeping cankers, and all manner of ailments affected the conifers I tended. In many cases, the prognosis was grim, warranting removal of whole rows or costly applications of fungicide.

Southern Minnesota is often a humid place, susceptible to drastic changes in weather. Exotic species of evergreens, especially the ever-popular and ever-dying Colorado blue spruce, are not adapted to live in Minnesota. In fact, the only evergreen that is native to southern Minnesota is the eastern red cedar, widely considered a tough weed in pastures and fields today. Other Minnesota native conifers such as white spruces and balsam firs thrive in the northern woodlands, but it is important to remember that the climate in Ely is not the same as Mankato.

Unfortunately, back in the 80’s, maladapted trees such as the Colorado blue spruce were recommended by the University of Minnesota and county conservation districts. It was easy to see why spruces were so popular—attractive foliage and a second-to-none privacy screen for yards. However, it was difficult to gauge at that time how spruces would survive after several decades of Minnesota weather. As many homeowners have now seen these past few years with outbreaks of Rhizosphaera needle cast, they definitely know now.

What worries me today is that many tree companies and some conservation districts are marketing a Colorado blue spruce look-alike, Meyer spruce, which is touted to be more disease resistant to needle cast and blights. That may be true, but Meyer spruce’s origin is Mongolia/China, hardly the same environment as the upper Midwest. I would wait a while longer to see if any issues appear with them before planting whole hedges.

To avoid being a statistic, consider planting native trees instead of flashy exotics. Look at Minnesota DNR’s native plant list (https://webapps8.dnr.state.mn.us/restoreyourshore) to find trees suited to your area. To simulate the great privacy/windbreak characteristics of conifers, think about planting a row of hardy shrubs in front of a row of native trees. Often these shrubs, such as serviceberries or chokeberries, can provide a source of food for you as well as local wildlife. If you simply must have a conifer, look for species such as white pines, arborvitae, or Norway spruce instead of Colorado blue or Black Hills spruce. However, these resistant species are not immune to disease, and often are sensitive to winter drying injury and road salt.

Trees are mortal, and often it is not one disease or insect that kills any tree, but a collection of factors. Native plants have a better chance of pulling through than exotic ones. When making a decision to remove a diseased tree, please consult with an International Society of Arboriculture (ISA) certified arborist, to find one near you visit http://www.treesaregood.org/findanarborist. Make sure the tree company also has insurance in case of accidents.

Sadly, despite my pleas for adapted species, people have told me they simply want a fast growing tree to enjoy for a few years, regardless of how long it will live. If the tree gets sick in a decade or so, it will be another homeowner’s problem, not theirs. This somewhat selfish viewpoint may be generational, but I fear it is more human nature—the same nature that overturned the delicate balance of prairie and forest that Aldo Leopold opined about.

Works Cited:

  • Leopold, Aldo, 1886-1948. (1949). A Sand County almanac, and Sketches here and there. New York :Oxford University Press
  • Minnesota Department of Natural Resources. Restore Your Shore. https://www.dnr.state.mn.us/rys/index.html
  • Smith, Marvin E.; Scholten, Harold. (1981). Planting trees in Minnesota (revised 1981). University of Minnesota. Agricultural Extension Service. Retrieved from the University of Minnesota Digital Conservancy, http://hdl.handle.net/11299/168888.
  • Smith, Welby. Trees and Shrubs of Minnesota. University of Minnesota Press. (2008).