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Purdue Landscape Report: We receive a large number of spruce samples each year at the Purdue Plant and Pest Diagnostic Laboratory (PPDL), with the vast majority being from Colorado blue spruce with needlecast. Many others show lower needle yellowing, which could be associated with nutrient deficiency or root stress.
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Figure 2: A young spruce tree under the effects of transplant and root stress.

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Figure 1: A spruce tree suffering from root damage and water stress.

However we are receiving an increasing number of Norway spruce samples with small branch dieback from the tips. This tip dieback symptom can have many causes: cold injury, root damage manifesting in branch dieback, Diplodia tip blight (caused by Diplodia sapinea, the same pathogen that causes tip blight in pine), and Cytospora canker. Phomopsis, another fungal pathogen which causes tip blight on spruce in nursery situations has been observed in greater frequency since 2012 by plant diagnostic labs in the North Central region causing cankers and tip dieback in more mature spruce trees in the landscape.
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Figure 4: Phomopsis dieback with excessive needle loss on branch tips.

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Figure 3: Dieback symptoms in a mature tree associated with Phomopsis infection.

The disease begins in the lower canopy and moves upward, but in some cases it progresses quickly, causing dieback through a large portion of the tree. Besides needle death and drop, there are virtually no other external symptoms to indicate where the original infection took place. Occasionally you may find resin building on the outside of a canker. Cutting into the thin bark will show the brown discolored tissue where the canker is developing. Cankers are often located in between two areas of healthy tissue. This can lead to older needle loss similar to needlecast diseases, but leaving terminal buds alive. However, once the pathogen spreads and girdles the branch, the rest of the branch will begin to die out to the tip.

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Resources
Borers of Pines and Other Needle Bearing Evergreens in Landscapes, The Education Store, Purdue Extension resource center
Ask an Expert Question: Blue Spruce dying, what can I do?, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Why Spruce Trees Lose Their Needles, Purdue Extension
Diseases Common in Blue Spruce, Purdue Extension

John Bonkowski, Plant Disease Diagnostician
Purdue Department of Botany and Plant Pathology


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