tt-94 BY DON MEEHAN

SPRUCE TREE NEEDLE DROP

Spruce trees are a beautiful landscape plant if all of their needles are present. All too often I see these ornamental trees with hollow centers where the needles have fallen off. This problem is so bad that some Washington State University County Agents discourage people from planting these trees in western Washington. This particular problem of the spruce tree is caused by the Spruce Aphid. It is a small dull-green aphid that feeds on spruce needles during the late winter and sometimes into the spring. New growth needles don't show the damage. They look healthy. Only needles which are two or three years old drop off, leaving the center of the tree hollow. When this problem persists year after year, the effect of the hollowing center is very pronounced. The aphids have essentially sucked all of the juices out of the needles so that when spring and summer arrive those needles are badly damaged. The needles show yellow blotches and later turn entirely yellow or brownish, and drop off the tree. Aphids disappear in the spring, but the symptoms don't appear for a while afterwards. People will be knocking on my door in late spring or during the summer wanting to know what to do about their tree after it is too late to do anything. The only thing effective is to spray for the aphids when they are present in February and March. The insecticides that work best and are recommended by Washington State University are Thiodan 9.15% EC, Diazinon 25% EC, or Malathion 50% EC. Less toxic means would be to use insecticidal soaps or high pressure hosing to blast the aphids off the twigs. Insecticides are dangerous substances to humans if used improperly. An additional point to remember is that aphids are more likely to attack a tree or plant that is weakened or under stress. Therefore, you'll want to give your Spruce extra care. For additional information on Spruce Aphid control measures, contact our office for a 25 cent publication called "Spruce Aphid". We'll be glad to mail you a copy.




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