What Is Wrong With My Spruce?

Are there any galls on shoots?

Are the leaves defoliated, and twigs girdled?

Does the tree wilts, new growth is deformed?

Are the needles turning yellow, fine webbing may be present?

Did the tree become girdled, sawdust material may be present?

Are the needles webbed together?

Did the tree become defoliated?

Are the needles dropping, branches die back, resinous cankers appear?

Are the needles blistered and discolored?

Spruce gall aphids cluster on the tender new growth at the ends of branches of spruce. You can control them by washing them off the plant with water spray. Introducing ladybugs will keep their number low. Insecticidal soap or neem oil should be used with severe infestations.

Bagworms are small, brown caterpillars that feed on inside the silky, white bags they create. 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. Handpick and destroy all the bags. If you notice crawling caterpillars you may have to use insecticide as they are really hard to get rid of.

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.

Spruce spider mites are tiny pale green insects that attack all kinds of evergreens. You can control spider mites by spraying plants thoroughly with water 2-3 times a day for several days. For severe infestations, spray plants with insecticidal soap.

Hemlock borer larvae are half an 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. If you see borer holes in your trees, probe into them with a flexible wire or inject a solution of parasitic nematodes.

Spruce needle miner adults are small gray or brown fringed-winged moths. Their larvae are greenish to brown worms with black heads. 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. 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.

Sawflies often leave whole branches of the spruce trees defoliated. In June, the small, wasplike adults lay eggs in the side of spruce shoots, causing shoots to twist. Grayish green, caterpillar­like larvae emerge about a week later. They feed on the needles, starting with lower branches. Remove debris from around trees, which provides an overwintering site for the pest. Spray shoots with superior oil to control heavy populations.

A 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. The disease attacks trees weakened by drought, winter injury, insects, fire, and mechanical injuries. 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.

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.

Your tree may be just 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.