Colorado blue spruce trees can grow up to 85 feet tall, according to North Dakota State University. It is a common landscaping tree that is also used in windbreaks. Birds love to nest in its protective branches and it’s a popular type of Christmas tree. Trees that have begun to develop brown needles could be succumbing to needle cast disease (Rhizosphaera kalkhoffi), a common fungal infection in blue spruce trees. Of course, the best way to save trees from the fungus is to prevent its development in the first place.
Clean up fallen needles from around the base of infected trees. Seal these needles in a bag and throw them in the trash.
Have mature trees treated with a Bordeaux mixture or chlorothalonil fungicide. It’s best to have a professional tree service work with mature trees, as they can be very tall and most homeowners lack the proper equipment. A tree service will apply the mixture or the fungicide when the needles are half formed and again once they’ve reached their full length, according to New Mexico State University. According to NMSU, two years of treatment should do the trick.
Replace dead spruce trees with a different species so the new tree doesn’t succumb to the same fungus.
Plant healthy trees. Inspect trees thoroughly before purchasing them and inspect all the trees your landscaper wishes to plant. Trees that look unhealthy when they’re young aren’t going to grow up healthy.
Plant blue spruce trees in the right conditions with enough space to encourage good air circulation. The University of New Mexico advises that new plants shouldn’t be planted next to established trees.
Keep the area around trees tidy. Put down a couple of inches of mulch to keep down weeds, keep the grass mowed to a healthy height and clean up any debris where they fungus spores may hide. In the interest of preventing the spread of the disease, sterilize pruning shears between cuts.