Location – Cambridge, Ontario Partial Shade
We moved to our home last year and found that the 2 blue spruce shurbs were losing all of the needles on the tips. (trunks approx. 4″ dia)
The nearby overgrown euonymous had scale and we removed the entire plant. I gave the spruce shrubs a pruning and cut off all of the affected tips and hoped for the best.
This year, one of the plants has new growth on almost all of the tips but the other has a little new growth on the lower portion of the plant but the upper branches are not looking healthy. In the last few days, I have found insects hanging from the branches.
In your opinion, what is happening and can the plant be saved?
Thanks for any advise you can offer
Thank you for contacting Toronto Master Gardeners.
Colorado Blue Spruce, Picea pungens, is a beautiful tree often used in landscaping. For the tree to thrive it needs full sunlight and very well drained soil with good air flow around the branches. You do not mention the location of the trees but it is worth noting if they were planted in an ideal spot for them to thrive.
There are many things that can affect the tree and often there is more than one cause to the problem. When disease moves in it will begin attracting pests so you may need to work on more than one thing to help the trees. Is the damage to the tree happening all around the trees or is it restricted to a specific location or side? If this is the case you need to look at possible issues in the location that could be causing the die back.
Before you can create a plan to help the trees it is important to correctly diagnose the problem. Different pathogens will require different treatments.
The three main diseases of this tree are: Needlecasts- kills older inner needles, Tip Blight- kills newer growth and Canker disease- has cankers on the stems and kills the branches. From your description it sounds most like a blight. Treating this requires the correct fungicides for the specific strain you are dealing with.
Insects that affect the trees are; gall adelgids and spruce spider mites. Both of these insects are very small. Before treating for insects you will need to be sure you have correctly identified them . Pesticides target specific life cycles of the insects and timing is crucial for it to be effective.
All of the possible diseases will continue to cause the decline of your trees. The best course of action is to call in a certified arborist. They will know what diseases and insects have been in the area and will now what to look for. Through inspecting the trees they will be able to pinpoint the problems and help you plan a pest management program. They also have access to chemicals you may need to employ and will know how to use them for maximum effectiveness.
To find an arborist that is fully qualified you can visit the following site: