Spruce Tree Problems
This article was originally published on May 31, 2017 and expired on July 31, 2017. It is provided here for archival purposes and may contain dated information.
Master Gardener Column
By Jan Phipps
Several people have said to me, “My spruce tree seems to be dying.” My standard answer is, “So are mine.” Look around and you will notice many spruces are in really bad shape. In my research, I have narrowed it down to two fungal diseases: Rhizosphaera needle cast or Cytosprora canker. Both are bad news.
Rhizosphaera needle cast starts at the bottom and works its way up the tree. Sound familiar? Most infections occur in the spring during bud break but don’t become apparent until fall, or even the next spring. It is normal for four and five-year-old needles to drop, but infected trees lose all the needles except the current year. The spruce looks empty on the inside with just a tuft of needles at the outer limit of the branches. Next year the entire branch will be brown or bare.
There are some fungicides that can protect new growth on trees that are only moderately infected. They need to be applied for a minimum of two years and be specially labeled for control of Rhizosphaera. Read the label very carefully as some are not recommended for blue spruce trees.
Cytospora canker attacks stressed trees, especially Norway and Colorado blue spruces that are at least 15 - 20 years old. It, too generally starts at the bottom but can also exhibit sporadically throughout the tree. The whole branch dies. Look closely at the base of the branch near the trunk. The canker appears as small white patches of white dried sap and resin. Unfortunately, there is no control for Cytospora canker.
Why are so many spruces showing symptoms now? It appears the spruces were affected more severely by the 2012 drought than we thought. Some trees showed drought stress immediately, like arborvitae trees and shrubs. Other trees were weakened, making them susceptible to disease, which then took years to become severe enough for us to notice. Our spruce trees fall into that category. Following the drought summer, we had one unusually cold winter followed by quite a few cold, wet springs. Fungal diseases love wet springs. The drought and winter stressed the tree allowing fungal diseases to move in and thrive in the damp conditions once they appeared.
If you choose to plant another spruce tree, picking the right variety and planting it in a spot that is optimal for its growing conditions is a preventative start. While many varieties of spruce trees are sold in Illinois, not all like our growing conditions. Many prefer thin, dry mountain air instead of hot humid summers. Keep the roots watered during a drought and mulch with an organic mulch to lessen soil temperature and wet/dry extremes. Do not crowd them. They need plenty of air circulation. Spruces have been a favorite choice for wind breaks because of their density. That may be good for the homeowner, but is not helpful to a species that needs lots of air and space.
I am going to lose all my spruces. All three are infected even though they are all different varieties. They have been there for over 35 years and I’m going to miss them.
Please call the University of Illinois Extension Master Gardeners of Edgar County if you have a gardening question in which you need help. We can be reached at 217-465-8585.
Pull date: July 31, 2017
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