Needle Cast: Why You Need To Protect Your Blue Spruces

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Blue spruce trees

Blue Spruce in MichiganIt’s the time of year your deciduous trees shed their foliage turning the focus of your yard to your evergreens. Nothing paints a better picture of a Michigan winter than a snow covered pine tree. But you noticed that some of your evergreens are looking little a thinner than usual, specifically your blue spruces. This is a common problem with blue spruces in Michigan and it’s called needle cast.

Why Blue Spruces?

Blue Spruces are not native to Michigan. They are native to Colorado but are a very popular tree to plant in Michigan due to their beautiful blue and lush appearance. But his makes them susceptible to slight changes in the environment and diseases. Needle cast is caused by the fungus Rhizosphaera kalkhoffii. Infected needles on the tree and those that have dropped off, produce spores that can be blown or splashed to healthy branches or trees.


The most glaring symptom of needle cast is branch dieback. Starting with the lower and inner branches first. Which then progresses to the rest of the tree over two to four years, making the tree look sickly and unattractive. So to identify the fungus look closely at the infected needles. You will be able to see lines of small black dots along the surface. These black dots are where the spores live and are released by moisture.

Blue Spruce

How To Treat It

Fungicides may be effective in preventing or controlling the disease. For it to be effective you must cover all susceptible needles, which can be an impossible task if you have several large spruces on your property. For a situation like this, you should call a professional. If you think your spruces are looking a little lackluster, then contact Go Green and ask about our needle cast fungicide program.

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