spruce trees.

(Question)

About 20 years ago I planted two blue spruce trees in the north/east section of our garden in what was once part of the Hunt Club Golf course on Kingston Rd in east Toronto.

Both trees thrived and grew to a great height. Recently I noticed that the colour of about a third down from the top of one of the trees had changed colour from blue to a light green. The extreme top of the tree is slightly bent. The other tree looks blue and healthy.

 

(Answer)

Problems with evergreen trees can be tricky to diagnose.  Lightening of the needles can be an early warning of environmental stress brought about by drought. This can be observed from the top down, but also randomly throughout the tree.   A bent top of the tree, often described as looking like a shepherd’s crook, is one of the signs of infestation by the White Pine Weevil, which despite its name can also attack various species of spruce. Soils can lack elements which can cause the spruce tree’s needles to change colour.  This condition is known as chlorosis, and can be due to a lack of such minerals as iron, manganese or zinc.  These minerals may not be able to enter the tree’s root system if the soil is overly alkaline.  Overfertilization with a high-nitrogen turf food can cause foliage to fade.  Colorado spruce (P. pungens) is also susceptible to a variety of insect borers and fungal diseases.  We know that environmental stress leaves trees vulnerable to pests and diseases.  You may wish to consult an arborist.  Landscape Ontario provides a useful list of arborists in your area.

Resources:

https://healthycanadians.gc.ca/product-safety-securite-produits/pest-control-products-produits-antiparasitaires/pesticides/tips-conseils/weevil-charancon-eng.php

https://homeguides.sfgate.com/causes-spruce-tree-turn-light-green-67973.html

https://lancaster.unl.edu/hort/articles/2012/DroughtDamage.shtml

https://www.extension.iastate.edu/harrison/news/common-diseases-blue-spruce

https://extension.illinois.edu/focus/index.cfm?problem=cytospora-canker-of-spruce