By Jeff Burbrink
Purdue Extension Elkhart County
GOSHEN — Spruces all over the Midwest are going through a decline. There is not a whole lot we can do about it. While beautiful in shape, color and texture, spruces are not native to our region, and that plays a role in their demise.
Affected spruce often look thin, perhaps losing a branch here or there, most commonly in the lower levels of the tree. Over time, the tree thins to the point it is no longer attractive.
In the wild, spruces grow in mostly arid, thin-soiled, mountainous regions. Since the 1970s, spruces have become a staple in the Midwestern landscape. The Midwest has rich, deep-textured soils and higher temperatures than spruces are used to. The roots of spruce are normally anchored in rocky crags, but in the Midwest, the mellow soil is often not firm enough to hold a towering spruce firmly when the wind blows.
The Midwestern air works against spruces, too. Our summers are humid, and humidity has the nasty habit of stimulating plant diseases that attack spruce. There are several different diseases going after spruces here, including needlecast, tip blights and various canker diseases.
Many people want to spray a fungicide when they learn their spruce has a disease. This strategy does not work well. Fungicides are protectants, meaning they need to be applied before the plant is showing major symptoms. Fungicides also require reapplication as long as conditions are ripe for disease growth, which means multiple applications throughout the season are needed. Since fungicides are expensive and are difficult to put on in a timely fashion, the fungicide strategy rarely works.
If diseases, soil type and humidity were not enough, spruces also have several insect pests that frequently attack them. The two most common are gall adelgids and spruce spider mites. In both cases, the insect pests are tiny and you may need a hand lens to see them. Often times, people are more likely to see the damage as opposed to the insect pests themselves.
So why are we seeing this happen now? When there were just a few spruce trees in the region, one or two sick trees would rarely be enough to spread disease and pests to those around them. But, the more spruce we planted, the higher the chance that an epidemic would occur. And that is where we are today.
When a spruce begins to look bad, you might be able to get a few more years out of it by pruning off the dead branches, but at some point, it will no longer look pleasant, especially when arranged in large groups as a privacy screen. Consider planting other species of conifers to replace the spruce that might be more tolerant of Midwestern conditions. Michigan State has a publication at www.shorturl.at/chilL listing some excellent choices for spruce replacement.