Blue Spruce - Ask Extension
I have several 15 to 20 foot Blue Spruce which have been diagnosed with Spruce Spider Mites. What can I use to get rid of those pests?
Knowledgebase
Blue Spruce #707489
Asked July 30, 2020, 4:21 PM EDT
I have several 15 to 20 foot Blue Spruce which have been diagnosed with Spruce Spider Mites. What can I use to get rid of those pests?
El Paso County Colorado
Expert Response
Hello
Are you confidant that the diagnosis is correct? You do not say what is going on with the trees, and you did not include any photographs of the trees or the damage. I will answer the question assuming that the diagnosis is correct.
There are several ways to control the damage spider mites can do. There are chemical miticides, but they do not effect the eggs so repeat applications may be necessary. Perhaps the most important control is making sure the trees are adequately irrigated to minimize damage. Here is a link to a fact sheet which will give you some treatment options.
Feel free to reopen the question if you would like help confirming the diagnosis.
Response to your first question, unfortunately No, I am not confident in diagnosis.
i will attach some photos.
i have been fighting this for several years. Had a couple of arborists out and one told me ‘hail damage’ one the spruce spider mites he showed up once last year to spray (talstar). Did not want to come back to spray this year- too busy. Needles turned brownish starting lower on tree and has moved upward over past two years. Do have great new growth from last two years . So damage is inward toward trunk. I have had a couple of the crooks (picture 1) which I have cut off where I can reach them. If you need better closeup pictures of branch and needles let me know.
i will attach some photos.
i have been fighting this for several years. Had a couple of arborists out and one told me ‘hail damage’ one the spruce spider mites he showed up once last year to spray (talstar). Did not want to come back to spray this year- too busy. Needles turned brownish starting lower on tree and has moved upward over past two years. Do have great new growth from last two years . So damage is inward toward trunk. I have had a couple of the crooks (picture 1) which I have cut off where I can reach them. If you need better closeup pictures of branch and needles let me know.
Thank you so much for taking time to review my problem.
Hello
The photos are helpful. The appearance of the needles could indicate spider mites. I would like you to try the following test. Take a sheet of white paper perhaps resting on something like a cookie sheet. Hold it under an effected branch and shake the branch. Look at the paper to see if you can see the mites. They are very small and this is not the best time of year to do this but if you see them that will be diagnostic. Look for moving insects, if you have a magnifying glass you may be able to make out the shape. Let's start with that and see what that tells us.
I tried the white paper test and only one possible mite was on the paper. I repeated the test several times- some with no mites.
i included a photo of the orangish brown ‘branch’ on one of the trees. What is this? Also include another picture of the tree with new growth .
thank you so much for your time on this.
i included a photo of the orangish brown ‘branch’ on one of the trees. What is this? Also include another picture of the tree with new growth .
thank you so much for your time on this.
Gene Mills
Hello Gene
I have a feeling perhaps two things are going on with these trees. Despite the white paper test being inconclusive I really do think mites are probably at work here. The reason is the damage on the needles is consistent with a mite infestation. It would have been nice if the paper had been obvious confirmation but the test is best performed in spring.
The browned tips may be the result of winter desiccation. We have had weather patterns the past two years that have been quite damaging to woody plants. Starting with the very late blizzard in May 2019, followed by two mid to late October deep freezes, the a very deep freeze in mid April 2020, trees were really stressed. The sudden fall weather change in particular gave woody plants no time to prepare for dormancy. You may not recall that there was a 24 hour period in October when the temperature went from 80 degrees to 15. We had very dry December and January weather.
Control of mites can be done. Below you will find a fact sheet listing several options. The most important thing you can do for these trees is make sure they are well hydrated. That will treat the desiccation, and help control the mites. If you want to try chemical controls for the mite population I suggest you wait until the weather cools, mites are inactive during warm weather and can go into a dormant state (hence the failure to see them on the white paper). Make sure that you winter water these trees this year. I think that is probably the best thing you can do at this point. I hope this helps.
