Updated: 6:41 p.m. Friday, May 13, 2011 | Posted: 6:40 p.m. Friday, May 13, 2011
What to do about your suffering spruce trees
By Pam Corle-Bennett
What is wrong with my spruce trees? If I had a dollar for every time I have heard this question this spring, I wouldn’t quite be rich but I could eat at a very nice restaurant!
A lot of people are experiencing problems with spruce trees, specifically needles dropping and branch dieback.
Much of what I am seeing is due to last summer’s drought. Remember August, September and October? It was quite dry with deficits (in inches) of -1.00 in July, -1.76 in August, -1.00 in September, -1.59 in October and -1.63 in December in the Dayton area.
Do you remember the cracks in the soil? Roots that were within the areas that were cracked were exposed to air and likely died out.
In addition, warm temperatures added to the rainfall deficits caused plants to really struggle.
When presented with a sample of a spruce with dieback, I first take the time to rule out any potential insect and disease problems.
Dothistroma, cytospora canker and Rhizosphaera are three diseases that we tend to see on spruces in Ohio.
Each of these diseases has different symptoms that can lead to needle drop. For the most part, however, diseases tend to affect the overall plant in a random pattern with symptoms scattered across the tree.
Drought symptoms, on the other hand, tend to cause the plant to die back from the bottom to the top or top down, but damage is dispersed evenly across the plant.
There are also mites and insects that damage spruces as well. The cool season spruce spider mite damage leaves a bronzish cast on the needles, and the bagworm eats needles to form its protective bag.
Mites don’t usually cause needle drop unless the infestation is really severe. I have not seen this type of infestation in my lifetime. Bagworms can strip a tree completely and definitely should be controlled.
The first step then, in determining what is going on with your spruce is to rule out a disease or insect or mite.
Then, the only other option is usually root damage due to drought. On top of this damage, we have trees that have been sitting in water for a long time this spring, severely compromising the roots.
The only thing to do with drought damage is wait it out. If there is no new growth on a branch, trim this branch, cutting all the way back to any green or the trunk if necessary.
Never fertilize plants that are in root stress; they don’t have enough roots to absorb nutrients and you may add salts to the soil that cause more harm.
Pam Corle-Bennett is an Ohio State University Extension horticulture educator and the state Master Gardener volunteer coordinator.
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