Dying Blue Spruce

Asked May 2, 2013, 11:47 AM EDT

I have a blue spruce that has been dying off for the last few years and now is completely dead. It is about 50 ft tall. My concern is there is another I believe it is blue spruce that a landscaper said I should have it looked at. He said it is getting sparse from the trunk out towards the end of the branch and you can see through. He said you should not be able to see through this that it should be full of needles all the way back. I am worried we are going to lose this one also. is there some known disease or pest that is killing spruce trees?

Barry County Michigan

1 Response

What you are describing sounds like Rhizosphaera needlecast, a fungal disease that affects blue and white spruce only. Needles become infected starting closest to the ground and to the interior of the tree, closest to the trunk. All needles except the current year's needles can become infected. Next year, those new needles can become infected. Needles turn brown...the color of a chocolate bar...and are shed off in the late summer and fall. This gradually works itself up the tree. Trees do not recover on their own. If 50% ot more of the tree is affected, the tree probably cannot recover.

If you look at the infected needles with a magnifying glass, you will see that the lines of white pore openings or stomata, are affected. Some of the openings look like there is a microscopic black pingpong ball being exuded from the opening. These will be scattered.

If you decide to treat the tree with a fungicide (chlorothalonil), you will be spraying every three to four weeks from mid May until probably October. You will probably never be able to stop spraying, year after year. For most blue and white spruce owners, the disease is pretty much a death sentence for the trees because the spray regimen is so intensive. Good luck.