conifer pests?

Asked June 25, 2017, 1:29 PM EDT

Good Morning - Recently I have had a hemlock suddenly die, and a spruce in another part of the yard, began losing needles in one section. How can this be diagnosed and I hope, treated? Thank you for your help. I live on about 2 acres adjacent to a regional park. We have well and septic. We do not use pesticides. - Boyds, MD

Montgomery County Maryland

1 Response

Hemlock trees are susceptible to an insect pest called the hemlock woolly adelgid. If not treated, they will decline. Here is more information about it

Blue spruce - can be susceptible to Cytospora canker and Rhizosphaeria needlecast, fungal diseases. Blue spruce, in general, are not really well suited for our area as they are native to climates further to the north. Cytospora canker occurs on trees stressed by drought or other site conditions. There is not much you can do other than water during dry periods. Make sure mulch is no thicker than several inches and keep away from the base of the trunk. Prune dead plant material during dry weather.

Rhizosphaeria needle cast disease. The infection period is long - spring through midsummer. The needles are affected in the fall and needle drop occurs in the spring. Pruning out severely infected branches is the best control method on branches that show sparse growth. Spraying large trees with fungicides can be complicated - getting good coverage, timing, etc. and not recommended. For more information see the link on our website