Pine needle scales are some of the most destructive insect pests affecting conifer shrubs and trees in Colorado, specifically Summit, Eagle and Grand counties. Pine needle scale feeds on the needles of most pines and spruce. During heavy outbreaks the needles look like they have been splattered with white paint. From a distance the trees may have a silvery appearance. Persistent infestation will result in reduced plant vigor, significant needle loss and eventual death of the tree. It may take several seasons of infestation before a tree will begin to shed its needles, so it is very important to check your trees.
At this elevation, pine needle scale typically hatch and are in the “crawler” stage from the second week of May through the second week of June with a second hatch generally in late July, with anecdotal evidence of a third hatching in September, depending on environmental conditions.
Populations may be active from a few hours to a few weeks. This active period is the best time for control of this insect. Timing and monitoring are critical when planning applications; depending on the level of infestation, several treatments in one season may be needed to properly control these insects. Although your trees may appear to be at death’s door, do not give up hope. There are several application procedures available ranging from foliar sprays which can include horticultural oils and soaps (organic alternative) as well as insecticides, to soil injections and trunk applications, depending on the size of the tree to be treated.
A proactive approach utilizing deep root fertilization, to increase the vigor and health of the trees, as well as an insecticidal application will ensure good tree health. Pine needle scale is an innocuous insect that can do severe damage without your knowledge. It is critical to preserve and protect your valuable landscape investment. A licensed and insured tree care professional can tell you if you are in danger of losing your trees.
Mike Stankelis is the owner of Ascent Tree and Turf Services, serving Summit and Eagle counties. He may be reached at 970-393-3877. For more information, go to www.ascenttree.com.