For about 10 years, spruce trees have had a tough time in Michigan due to pest, diseases, over-planting and weather. Diseases with spruce are nothing new. Cytospora Canker is manifested by the dying of the lower branches accompanied by dropping of the needles. The disease is very destructive on the blue spruce. But a recent survey in southern Michigan by Dr. Dennis Fullbright (MSU Department of Plant, Soil, and Microbial Science) has discovered that this disease is not as prevalent as in the past. A new disease, Phomopsis Blight, has shown its ugly head on one of Southeast Michigan’s favorite conifer (i.e. Christmas tree or evergreen tree). This disease as described in an article in the magazine The Michigan Landscape works much faster than the Cytospora Canker.
So what can we do to stop or prevent this disease? The future does not look very bright for infected plants. Fungicide and pruning can help, but dead branches will not grow again. If you do not catch the disease soon enough, much of the lower branches of the plant will be gone. Bad news if the plant is used for privacy. A fungicide, Cleary 3336, can be used to prevent the disease. But this needs to be applied several times while the shoots of the plant are growing the spring. This could be a very expensive endeavor.
As with the Elm Dutch Disease epidemic in Detroit in the 50’s and most recently the Emerald Ash Borer, diversification is key to slowing down insect and disease issues in our landscape. Colorado Blue Spruces have been planted heavy in the last 30 or so years. They are loved for their color, availability in the market and tolerant of our heavy soils here in Southeast Michigan. We should consider using and actually make it a point to plant other types of conifers. Please check out this extension handout by MSU. As a landscape contractor and designer, I will do my best in educating my clients on other choices.
This tree Colorado Spruce (Picea pungens) is in a row with four other Colorado’s and one Norway Spruce. The plant declined extremely rapidly this year and before I knew it lost a big gap of needles in the lower third of the plant. I have been treating all of the plants with herbicides and will deep root fertilize them this Fall, but will eventually replace at least this plant with another species of conifer. These trees provide privacy for my backyard and block road noise from the entrance of the subdivision.