Stem attacks on subalpine and Pacific silver firs may begin at 20-40 feet above ground and then move downward. The foliage in this case becomes yellow and turns red when the tree dies. The crown of grand fir becomes darker and thinner. The leader will often curl and later break off, leaving a flattened crown. Stem attack on the grand fir starts near the base of the trunk and moves upward.
Control is difficult with anything but high pressure spray equipment.
When adelgids are in the crawler stage look for tiny moving specks with a hand lens. Light scrubbing of the main stem and large branches with a brush and soapy water, or hosing with a strong stream of water may result in some reduction of the infestation. However, none of these last three methods have been tested. Trees planted as ornamentals or in arboreta are generally much more susceptible than those in natural habitats. In forests, pesticides are not an effective method of control.