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What Can Cause Browning Blue Spruce Trees? |
By Carl Wilson, Colorado State University, Horticulture
Many blue spruce trees around town have developed brown branches over the winter. Spruce trees are sensitive to the lack of year-round moisture. Three or more dry winters will have taken their toll if winter water was not applied. Stressed trees are now being attacked by an insect pest, Ips beetles, in several Front Range cities including Denver. Check for holes bored into the bark and look for woodpeckers on your trees hunting for Ips beetles for food. You can't go back and make up for moisture that wasn't there when spruce needed it this winter, and sprays will not reach beetles now inside the tree. You can apply a spray in spring to prevent additional beetles from entering your tree, and take measures to improve the tree's vigor. These include summer watering but especially future winter watering of the tree.
Photo: Judy Sedbrook
