Surface Roots Appear On Top Of The Soil
The Colorado Blue Spruce will sometimes produce surface roots if it is growing in compacted soils. For solutions see the file Dealing With Surface Tree Roots
Lower Branches Die; Tree Loses its Shape
Too Old - Spruces do not age well. The lower branches of Norway Spruce become ragged and eventually die as they age. Trees planted in groups begin to crowd one another and the branches no longer get enough light and space, so many experts suggest replacing them after years.
Galls On Shoots
Aphids - Aphids are soft-bodied, pear-shaped sucking insects, about the size of the head of a pin. They come in a variety of colors including green, brown, and pink. Spruce gall aphids sometimes cluster on the tender new growth at the ends of branches of spruce. There they form pineapple-shaped galls ranging from 1/2 to 2 1/2 inches long. Trees are weakened and distorted by heavy infestations. Do not plant spruce trees near Douglas fir that is a preferred host to these aphids.
Leaves Defoliated; Twigs Girdled
Bagworm - Adult male bagworms are black, clear winged moths. The wingless females and larvae (caterpillars) live in distinctive 2-inch long bags of tough silk. These telltale bags hang like ornaments on infested spruce trees. Camouflaged with browned needles, these bags hold eggs over the winter and enlarge to protect the caterpillars that hatch in May or June as they feed. Bagworm infestations are more of a problem in southern zones. They disfigure spruce trees by mutilating their needles and girdling twigs. Handpick as many of the bags as possible immediately.
Wilting; New Growth Deformed
Budworms - Spruce budworm caterpillars are 1/2 to 3/4 inch long. They are dark and reddish-brown with a yellow stripe along the side. As adults they are small dull colored moths. The caterpillar chew newly opened buds and needles causing them to wilt and become deformed. They are most abundant in June and July. These pests are serious problems on spruce trees in northern forests and can affect ornamental ones as well.
Needles Turn Yellow
Mites - Spruce spider mites are tiny pests only 1/64 inch long. The young are pale green; the adult female is greenish black. In the egg stage over the winter, the young emerge in spring. They are destructive to all kinds of evergreens. They cause yellowed, sickly needles on the spruce tree. Many are covered with fine silken webbing.
Tree Becomes Girdled
Borers - Adult hemlock borers are flat, metallic colored beetles with 3 circular reddish-yellow spots on each wing cover. The larvae are ½-inch long worms that damage the bark of living, injured, and dying spruce trees. They make sinuous interlacing, flattened galleries in the inner bark and sapwood, girdling infested limbs or trunk and interfering with the tree's circulation. They prey particularly on trees that are low in vigor due to drought, transplanting, bark wounds from yard-care equipment, or insect attack. Try to locate the telltale holes in stems. They may have sawdust around the entrance. The best preventative strategy is to try to maintain tree vigor. Proper fertilization, watering and pruning of damaged branches are important. Because newly transplanted trees are at risk, prevent borer attack by wrapping the trunk and largest limbs with burlap, newsprint or commercial tree wrap material from the garden center for their first season.
Needles Webbed Together
Spruce Needle Miner - The presence of dark brown moths flying about a spruce tree signals the arrival of the spruce needle miner. Adults are small gray or brown fringed-winged moths. Their larvae are greenish to brown worms with black heads, about 5/16 inch long. They emerge from eggs laid early in summer and burrow into the bases of spruce needles, webbing them together. This causes obvious patches of brown needles, webbing and frass to appear on spruce trees. Often the heaviest infestation of the spruce needle miner is on the lower branches, where many of the needles may be destroyed. Control this pest and the similar spruce leaf miner by washing the masses of dead needles off affected trees with a garden hose. Collect and destroy the debris.
Tree Becomes Defoliated
Sawflies - Adult sawflies are wasp-like, but with thicker midsections. They are 5/8 to 1 1/2 inches long, with 2 pairs of transparent wings. Their larvae resemble caterpillars, averaging 1/2 inch long. These larvae devour spruce needles and are capable of totally defoliating a spruce tree.
Branch Die Back; Needle Drop; Resinous Cankers
Canker - A destructive canker disease in spruce trees is caused by a fungus. Branches progressively turn brown and die, usually starting nearest the ground and slowly moving upward. Needles may drop immediately from infected branches or may persist for nearly a year. White patches of pitch or resin may appear along the bark of the dead or dying branches. The disease attacks trees weakened by drought, winter injury, insects, fire and mechanical injuries from yard care equipment. There is no effective treatment for this disease. Control it by pruning and destroying affected branches. Do this during dry weather and dip pruners in a solution of hot water and household bleach to avoid spreading the infection. Avoid wounding trees.
Blistered; Discolored Needles
Rust - Rust diseases caused by fungi cause whitish blisters to appear the undersides of spruce needles. They later turn yellow and may drop prematurely. Usually rusts are minor problems that do not require attention. However, a severe infection may defoliate the tree.