Cooley Spruce Gall

Cooley Spruce Gall

My neighborhood spruce trees have been attacked by aphid-like insects, Cooley spruce gall adelgids that make the ends or the new growth of each branch brown.  Colorado State University Extension has the best description of this pest.

My neighbor has asked to remove his tree because of his mis- diagnosis of the problem.  This gall doesn’t harm the tree, it just makes it look less healthy than it could.  Even applications of pesticides are not that effective in controlling the problem.  The indicator that I find strange is that it needs a douglas fir species to complete their life cycle, since we don’t have Douglas Fir in our immediate neighborhood, I’m quite perplexed to see such an abundance of the spruce gall affecting about 30 trees.

Western Spruce Budworm Damage

Western Spruce Budworm

Utah State has a great description of the Western Spruce Budworm  as does the Colorado State Extention.  This is a very debilitating worm that can kill off stands of spruce, douglas fir, white fir and subalpine fir.  Its larvae feed on young developing buds, needles, shoots, and other plant parts.

Spruce Cytospora Canker

Cytospora Canker

Colorado State Extention Description is very good.  This canker  is a fungi in the species cytospora and can kill the plant.  This canker affects many different kinds of trees and the only evergreen tree that is affected is the spruce.  The other trees that are also affected include apple, ash, aspen, birch, cherry, cottonwood, elm, maple, peach and willow.

Rhizosphaera Needlecast

The Rhizosphaera Needlecast symptoms of the disease are discoloration of the needles, needle drop, and eventual defoliation. Infected needles turn yellow in July and then reddish-purple in August. The needles eventually turn brown and fall off one to several branches. A severely affected tree will have many bare branches. Premature needle drop is the primary damage, causing the tree to become unsightly. However, branches that are defoliated for four or five years may die. If left uncontrolled, the disease can eventually kill the tree.  New Mexico State University has the best description.

How to distinguish between Needlecast and Cytospora

Overall, if you have browning needles on your spruce tree, they may be one of these problems.  It is best to determine which one it could be and utilize a control as soon as possible.  There are a few others possibilities that may make your spruce turn brown, although I haven’t seen much evidence around Durango Colorado.

Cheers,

David Hart

Gardenhart Landscape & Design

970-749-1555

http://www.gardenhartlandscapedesign.com

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