Dying limbs on blue arrow junipers - Ask Extension
We have 17 blue arrow junipers, approximately 6 feet tall. They were planted one year ago. We have not done any fertilization or supplemental waterin...
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Dying limbs on blue arrow junipers #150536
Asked September 02, 2013, 12:06 AM EDT
We have 17 blue arrow junipers, approximately 6 feet tall. They were planted one year ago. We have not done any fertilization or supplemental watering this year.
When we first planted these we lost three in short order due to what the nursery believes to have been spider mites. We have been spraying with Bayer Advanced 3-in-1 (Imidacloprid, Tau-fluvalinate & Tebuconazole) but our last treatment was in May.
Several of the plants have entire branches dying off. The worse one (by far) is in the attached pictures. In the last picture it is the middle plant, and you can see some of the dying branches on other plants.
I found a lady bug on this plant, but don't see any other signs of insect activity. Earlier in the activity we saw spider webs (and the spiders) spun between the plants, but haven't seen the spiders for a while.
Is it natural for the junipers to occasionally lose some branches, or is there something else to be concerned with?
When we first planted these we lost three in short order due to what the nursery believes to have been spider mites. We have been spraying with Bayer Advanced 3-in-1 (Imidacloprid, Tau-fluvalinate & Tebuconazole) but our last treatment was in May.
Several of the plants have entire branches dying off. The worse one (by far) is in the attached pictures. In the last picture it is the middle plant, and you can see some of the dying branches on other plants.
I found a lady bug on this plant, but don't see any other signs of insect activity. Earlier in the activity we saw spider webs (and the spiders) spun between the plants, but haven't seen the spiders for a while.
Is it natural for the junipers to occasionally lose some branches, or is there something else to be concerned with?
Oakland County Michigan
Expert Response
Dennis,
I am sorry to learn that you are having trouble with your junipers. Evergreens do naturally lose some needles, but the browning shown in your photos does not look normal. There are several possibilities for the needle problems.
Since the garden center staff suggested the possibility of spider mites, let’s begin with mites. Spruce spider mites do attack junipers. Unfortunately from the photos I can’t determine if spider mites are the problem. The following website provides a very good description of how to determine if your junipers have spider mites. The populations of spruce spider mites build in the fall, so you should begin looking for them now and during the next several weeks.
http://aces.nmsu.edu/ces/yard/1998/030998.html
The following website has some good photos.
http://woodypests.cas.psu.edu/FactSheets/InsectFactSheets/html/Spruce_Spider_Mite.html
If you do find signs of spider mites the first thing to try is a sharp spray of water that will dislodge the pest. If possible you want to avoid using pesticides because they will also kill the beneficial insects that keep the mites under control. The lady beetle you spotted is a beneficial insect. I am assuming the spider you saw is also a beneficial and not a spider mite. Spider mites are very small, and the web does not look like a traditional spider web (see the above website for a photo of spider mite webbing).
You also want to be sure the junipers are getting adequate water. A water stressed plant is more susceptible to mites. I realize that during part of this summer we have been receiving ample rain, but more recently there have been longer stretches of dry weather. You want the soil to remain moist but not soaking wet.
The Bayer 3 in 1 product will kill spider mites, but it will also kill many other insects. I would use this product only if you are sure you have spider mites and all other management strategies have failed.
In addition to spider mites there are several other pests that could be causing the browning. The following website contains a list of potential spruce problems and some photos. Possibly you can use this information to diagnose your problem.
http://www.clemson.edu/extension/hgic/pests/plant_pests/shrubs/hgic2056.html
The problem could also be related to cultural practices. You mentioned that the junipers have not received supplemental water this year. What about last year? Last summer was very dry. Lack of supplemental water may have contributed to the problem.
Is it possible that a herbicide was sprayed on the plants?
From the photos it looks like the mulch is touching the trunks of the shrubs. I don’t think this is causing your problem, but it is best to keep the mulch a few inches away from the base of the plant.
You mentioned that you did not fertilize this year. That is good. You don’t want to fertilize a stressed plant. Once the problem is managed you can fertilize based on the results of a soil test. In many cases trees and shrubs do not need fertilizer, and over-fertilization can cause problems. For this reason it is important to follow the recommendations of your soil test. If you have not soil tested the area within the last 3 years, you can obtain a soil test kit from the MSU Bookstore. The following is the website for purchasing the test kit.
http://bookstore.msue.msu.edu/product/soil-test-kit-selfmailer-1116.cfm
Diagnosing plant problems can be difficult. If you have looked at all of the above information and cannot determine the exact cause of the problem, you have several options.
You can bring a sample into the Michigan State University Extension-Oakland County Hotline, located in Pontiac. At this time of year it is a good idea to call before going because hours are seasonal. The telephone number is<personal data hidden>. The technicians can also tell you the size of sample to bring. There is a $5 dollar charge.
Another option is sending a sample to the diagnostic lab on the MSU campus. The website for the lab is
http://www.pestid.msu.edu/
Another option is a consultation with a certified arborist. An arborist will come to your property and can evaluate the plants, the planting methods and the environment. Some arborists will do an initial consultation at no cost. You can find a certified arborist in Oakland County at the following web site. Once at the site, select “find a tree care service” from the menu at the top of the page. You can then enter your postal zip code, and a list of certified arborists will be provided.
http://www.treesaregood.com/
I hope this information is helpful. Please reply back if you have additional questions. Thank you for using our service.
I am sorry to learn that you are having trouble with your junipers. Evergreens do naturally lose some needles, but the browning shown in your photos does not look normal. There are several possibilities for the needle problems.
Since the garden center staff suggested the possibility of spider mites, let’s begin with mites. Spruce spider mites do attack junipers. Unfortunately from the photos I can’t determine if spider mites are the problem. The following website provides a very good description of how to determine if your junipers have spider mites. The populations of spruce spider mites build in the fall, so you should begin looking for them now and during the next several weeks.
http://aces.nmsu.edu/ces/yard/1998/030998.html
The following website has some good photos.
http://woodypests.cas.psu.edu/FactSheets/InsectFactSheets/html/Spruce_Spider_Mite.html
If you do find signs of spider mites the first thing to try is a sharp spray of water that will dislodge the pest. If possible you want to avoid using pesticides because they will also kill the beneficial insects that keep the mites under control. The lady beetle you spotted is a beneficial insect. I am assuming the spider you saw is also a beneficial and not a spider mite. Spider mites are very small, and the web does not look like a traditional spider web (see the above website for a photo of spider mite webbing).
You also want to be sure the junipers are getting adequate water. A water stressed plant is more susceptible to mites. I realize that during part of this summer we have been receiving ample rain, but more recently there have been longer stretches of dry weather. You want the soil to remain moist but not soaking wet.
The Bayer 3 in 1 product will kill spider mites, but it will also kill many other insects. I would use this product only if you are sure you have spider mites and all other management strategies have failed.
In addition to spider mites there are several other pests that could be causing the browning. The following website contains a list of potential spruce problems and some photos. Possibly you can use this information to diagnose your problem.
http://www.clemson.edu/extension/hgic/pests/plant_pests/shrubs/hgic2056.html
The problem could also be related to cultural practices. You mentioned that the junipers have not received supplemental water this year. What about last year? Last summer was very dry. Lack of supplemental water may have contributed to the problem.
Is it possible that a herbicide was sprayed on the plants?
From the photos it looks like the mulch is touching the trunks of the shrubs. I don’t think this is causing your problem, but it is best to keep the mulch a few inches away from the base of the plant.
You mentioned that you did not fertilize this year. That is good. You don’t want to fertilize a stressed plant. Once the problem is managed you can fertilize based on the results of a soil test. In many cases trees and shrubs do not need fertilizer, and over-fertilization can cause problems. For this reason it is important to follow the recommendations of your soil test. If you have not soil tested the area within the last 3 years, you can obtain a soil test kit from the MSU Bookstore. The following is the website for purchasing the test kit.
http://bookstore.msue.msu.edu/product/soil-test-kit-selfmailer-1116.cfm
Diagnosing plant problems can be difficult. If you have looked at all of the above information and cannot determine the exact cause of the problem, you have several options.
You can bring a sample into the Michigan State University Extension-Oakland County Hotline, located in Pontiac. At this time of year it is a good idea to call before going because hours are seasonal. The telephone number is<personal data hidden>. The technicians can also tell you the size of sample to bring. There is a $5 dollar charge.
Another option is sending a sample to the diagnostic lab on the MSU campus. The website for the lab is
http://www.pestid.msu.edu/
Another option is a consultation with a certified arborist. An arborist will come to your property and can evaluate the plants, the planting methods and the environment. Some arborists will do an initial consultation at no cost. You can find a certified arborist in Oakland County at the following web site. Once at the site, select “find a tree care service” from the menu at the top of the page. You can then enter your postal zip code, and a list of certified arborists will be provided.
http://www.treesaregood.com/
I hope this information is helpful. Please reply back if you have additional questions. Thank you for using our service.
We planted them in September of last year. We did water them well until the end of October.
I took some photos and cuttings to a local nursery. They didn't find evidence of spider mites or fungus, but they think it might be transplant shock. Their suggestion was to fertilize with Holly Tone now and again in November.
Would fertilization make sense, or should I just keep them sufficiently watered (without over watering)?
I took some photos and cuttings to a local nursery. They didn't find evidence of spider mites or fungus, but they think it might be transplant shock. Their suggestion was to fertilize with Holly Tone now and again in November.
Would fertilization make sense, or should I just keep them sufficiently watered (without over watering)?
Dennis,
We don’t advise fertilizing unless you have a soil test that indicates fertilizer is necessary. Many of our soils provide sufficient nutrients for trees and shrubs. Too much fertilizer can cause a shrub to produce a lot of top growth at the expense of root growth. A shrub that produces an excessive amount of top growth is more attractive to insects. Excessive fertilization can also be harmful to the environment.
If you have not already had a soil test, I would recommend doing that first. Then I would fertilize in early spring according to the recommendations. I would not fertilize now because the plant is stressed. In addition, fertilizing at this time of year is not recommended because it could cause the shrub to add new tender growth that may not withstand extremely cold temperatures. Fall fertilization can be done after several hard frosts, but in your case I would not fertilize this year.
Keep in mind that regardless of how much fertilizer you apply, you will not “bring back” branches that are dead.
From now until the ground freezes keep the soil moist by applying supplemental water when we don’t have sufficient rainfall. Examine your shrubs frequently to see if there are any indications of insects, disease or additional stress.
I hope this information helps. If you have further questions, or if you notice a change in the shrubs, please reply back. Thank you for using our system.
We don’t advise fertilizing unless you have a soil test that indicates fertilizer is necessary. Many of our soils provide sufficient nutrients for trees and shrubs. Too much fertilizer can cause a shrub to produce a lot of top growth at the expense of root growth. A shrub that produces an excessive amount of top growth is more attractive to insects. Excessive fertilization can also be harmful to the environment.
If you have not already had a soil test, I would recommend doing that first. Then I would fertilize in early spring according to the recommendations. I would not fertilize now because the plant is stressed. In addition, fertilizing at this time of year is not recommended because it could cause the shrub to add new tender growth that may not withstand extremely cold temperatures. Fall fertilization can be done after several hard frosts, but in your case I would not fertilize this year.
Keep in mind that regardless of how much fertilizer you apply, you will not “bring back” branches that are dead.
From now until the ground freezes keep the soil moist by applying supplemental water when we don’t have sufficient rainfall. Examine your shrubs frequently to see if there are any indications of insects, disease or additional stress.
I hope this information helps. If you have further questions, or if you notice a change in the shrubs, please reply back. Thank you for using our system.
