3 different die-offs in same area - Ask Extension
1. (Norway?) spruce - top 6' or 7' of 60' tree has been dead 2 years. May have progressed one foot.
Disease, insect or other? Anything to be done?...
Knowledgebase
3 different die-offs in same area #418239
Asked July 31, 2017, 4:28 PM EDT
1. (Norway?) spruce - top 6' or 7' of 60' tree has been dead 2 years. May have progressed one foot.
Disease, insect or other? Anything to be done?
2. American boxwood - round, 8' diameter. Dead spots first appeared about one or two months ago. Disease, insect or other? Anything to be done?
3. unknown border shrub - all leaves apparently eaten by 1/4" black-headed white caterpillar-like bug. Anything to be done. Will it recover?
Note - #2 and #3 in vicinity of neighbors bright all night light newly installed this year. Could that have an effect? Thanks
Montgomery County Maryland
Expert Response
Your spruce looks like it's a Blue Spruce, and that is significant dieback on it.
This is not entirely surprising as they are native to cooler areas and often have problems with pests (mites, borers, adelgids ) and diseases (cytopsphora cankers, needle casts) as they age, especially if they are stressed by drought or other factors. We would
think that the tree's days are numbered and that you should consider removal, especially if it's fall would threaten people or property.
For your boxwood, there could be multiple common issues, including winter injury, leafminers, psyllids, and volutella, which will take a bit of sleuthing on your part. Take a look at this IPM:Boxwood publication for details: https://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/hgic/Publications/HG52_IPM_...
The problems on your boxwood don't look severe, but we would suggest in any case that you do some pruning- thinning cuts, not shearing- to increase airflow and sunlight within the plant, which can reduce future problems.
Here is a video to help you to accomplish thinning: https://www.youtube.com/watch?v=2U46_6bvkIA
For your third plant, we suspect it may be a shrub called a red-twig dogwood. The pest that ate the leaves is likely the larvae of sawflies. Unless this is happening yearly, which is uncommon, it is likely to recover and sprout new leaves. The newest branches of this plant are the reddest, so we'd suggest pruning it back in early spring to about nine inches, and let the new branches flush out. Alternatively, you could take about a third of the oldest branches all the way to the ground (again in spring) to encourage new growth. Repeated the following 2 years, you will have rejuvinated the whole thing.
We do not think that the neighbors lights had any effect on these plants.
cm
This is not entirely surprising as they are native to cooler areas and often have problems with pests (mites, borers, adelgids ) and diseases (cytopsphora cankers, needle casts) as they age, especially if they are stressed by drought or other factors. We would
think that the tree's days are numbered and that you should consider removal, especially if it's fall would threaten people or property.
For your boxwood, there could be multiple common issues, including winter injury, leafminers, psyllids, and volutella, which will take a bit of sleuthing on your part. Take a look at this IPM:Boxwood publication for details: https://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/hgic/Publications/HG52_IPM_...
The problems on your boxwood don't look severe, but we would suggest in any case that you do some pruning- thinning cuts, not shearing- to increase airflow and sunlight within the plant, which can reduce future problems.
Here is a video to help you to accomplish thinning: https://www.youtube.com/watch?v=2U46_6bvkIA
For your third plant, we suspect it may be a shrub called a red-twig dogwood. The pest that ate the leaves is likely the larvae of sawflies. Unless this is happening yearly, which is uncommon, it is likely to recover and sprout new leaves. The newest branches of this plant are the reddest, so we'd suggest pruning it back in early spring to about nine inches, and let the new branches flush out. Alternatively, you could take about a third of the oldest branches all the way to the ground (again in spring) to encourage new growth. Repeated the following 2 years, you will have rejuvinated the whole thing.
We do not think that the neighbors lights had any effect on these plants.
cm
