Trees in my yard are said to be severely infested with Hemlock elongate...

Asked September 25, 2013, 2:21 PM EDT

Trees in my yard are said to be severely infested with Hemlock elongate scale. Scale is on the underside of the needles. Do you what treatment options are available? And do you know how effective these treatments are? Instead of treating the trees, would it make sense to just let them die as they are quite old trees? Photo attached Thank you! Mary Klein

District of Columbia County District of Columbia

1 Response

Unfortunately, a heavy infestation of Hemlock Elongate Scale insects can kill a mature hemlock. If discovered early enough, it is possible to reduce the damage and to control the insects. Although we cannot see the entire tree in your photograph, it does appear that the background foliage is severely thinned out and there is obviously some die back. If the tree still has about 60% recoverable foliage, you could spray now with horticultural oil and then consider applying a soil drench of a systemic insecticide in early spring. Hemlocks are difficult to maintain in our area even under the best of circumstances.
LS