Blue spruce disease

Asked April 13, 2015, 10:55 AM EDT

What is wrong with our spruce trees and what we need to do to treat them? We have 13 trees that are 10 years old and they have all been affected. Late last Summer, early Fall we noticed that the needles were drying up, turning brown, and falling off starting at the tops of the trees. Last Fall we placed fertilizer spikes in the ground between the trees and treated them systemically with Trazicide, but the trees look worse this Spring. Is there anything we can do to save them?

Tazewell County Illinois

1 Response

Thank you for your note to eXtension.

There are several things that can cause the dieback you are seeing on these little spruce. Unfortunately, without being able to examine the plant directly, it's going to be hard to nail down exactly what you've got going on.

There are several needlecast and tip blight diseases that can cause these problems. Spider mite feeding can also cause needle drop. I've also seen instances where water-logged soils can start the plants to decline, or at least aggravate some of these other pest problems.

The first spruce in the picture is beyond salvaging. Even if I knew exactly what was wrong, I don't believe that this plant will ever regain its beauty and usefulness.

As far as the other plants go, I would suggest first checking for mites. There are cool season mites that are out now; there are also hot-weather mites, which will show up in June or July. Take a piece of white paper and hold it under some of the branches that are just beginning to get pale, and then smack those branches. If there are mites, they will drop to the paper and begin to slowly crawl around. If you see this, spray the plant with either Insecticidal Soap (NOT dish detergent) or malathion.

If you don't see mites, then try spraying a fungicide, such as Daconil (chlorothalonil). Spray when the new buds begin to open, and again about 3 weeks later. Only worry about the other shrubs in the back that have not died back like the first one.

Please let me know if you have any other questions.