What’s Wrong With My Blue Atlas Cedar?

February 16, 2018

If you’ve seen a Blue Atlas Cedar or own one, you know that these evergreens offer beautiful silvery, blue foliage that shines bright in the landscape. You’ve also probably come across one or two that look a little unhealthy. One of the most common problems we see with Blue Atlas Cedars (Cedrus atlantica ‘Glauca’) are the browning of its needles. This can be caused by a few different things:

  • Flagging- this is when only a few of the branches’ foliage turns brown and it is usually on the outer edge and will be scattered throughout the tree instead of in bunches. Flagging occurs naturally in cedars in late summer/early fall and they will shed old foliage to get ready for new growth. This is not cause for alarm.
  • Insects such as spider mites or weevils- spider mites eat the foliage and make tiny webs for their eggs and weevils burrow into the bark and lay their eggs in the bark. Both cause the foliage to turn yellow or brown
  • Sapsuckers- these are a small species of woodpecker that poke holes in trunks of trees to get sap and insects out to eat
  • Root rot- this is caused by fungus in overly damp soil
  • Fungus/bacteria- some fungi can cause blights which kill foliage while other fungi and bacteria can cause cankers, needles will start turning a pink/brown color when this happens
  • Over or under watering
Blue Atlas Cedar Browning

How do I fix these problems?

  • Flagging- since this occurs naturally you don’t have to worry too much about it. It may help to water your Blue Atlas Cedar more often. You can also prune off the flagging areas and it won’t harm the tree.
  • Spider mites- to see if your Blue Atlas Cedar might have spider mites, take a white piece of paper and place it below a branch where green foliage meets brown foliage. Tap the branch above the paper. If you see tiny red/orange dots crawling on the paper, those are spider mites. One way to make spider mites go away is by using a strong spray of water all over the tree to get them off the tree. If the water isn’t working, you can use a neem oil spray or you could think of adding in beneficial insects such as lady bugs or lace wing flies that will go after the spider mites.
  • Weevils- to check for Weevils or other borers, look at the trunk and branches of the tree to see if there are any pin sized holes (the holes may also be oozing a sap-like substance). You can use a neem oil spray to combat them.
  • Sapsuckers- the holes that sapsuckers make will look very similar to weevil holes but sometimes they are bigger. You can keep sapsuckers at bay by placing reflective items by the tree, such as pinwheels, to scare them away.
  • Root rot- one way to check to see if your tree has root rot is to pull upward on the tree to see if it starts to pull out of the ground easily. If it does and the root ball is mostly gone, your Blue Atlas Cedar may be suffering from root rot and means the roots may not be functioning anymore. Sometimes it is possible to save the tree from root rot by changing the soil around the tree so it has better drainage and applying a fertilizer. In many cases though, you will have to remove the tree.
  • Fungus/bacteria- to see if your Blue Atlas Cedar may have cankers, look for a discolored indent in the bark of the tree. If cankers are left unattended, they can swell and girdle branches and the trunk. You can remove cankers by pruning them off during cold weather. If your tree is suffering from blight (caused by fungi), make sure you’re cleaning your pruning tools before moving on to other plants to prevent the spread of the fungi. You’ll want to prune and discard the infected parts of the tree including any branches that may have fallen to the ground. Because this fungi is usually spread through water and often times in wetter than normal Springs, make sure that the Blue Atlas Cedar is located in well-drained soils and doesn’t have standing water around it.
  • Over watering- this can be a cause of root rot. If you’re noticing that the area around your tree is overly wet on a continuous basis, try scaling back the amount of water you are giving by either dialing back on how often you water and/or the duration of watering.
  • Under watering- Blue Atlas Cedars have fairly shallow roots so they need to be watered often in the first couple of years that they’ve been planted. If the soil is sandy or drains really quickly or if it’s been excessively hot out, you should check the soil around your tree to see if it’s getting enough water. The soil should be wet about 1 inch below the surface. To fix this issue, simply water your Blue Atlas Cedar more often and/or for longer periods of time. Once established, Blue Atlas Cedars can tolerate mild periods of drought.
  • It may also help to talk with your lawn/landscape maintenance company about what fertilizers or other treatments are being placed near the tree to see if there might be other reasons your Blue Atlas Cedar is browning.
Blue Atlas Cedar Problems


What are your tried and true ways of keeping your Blue Atlas Cedar looking beautiful and blue?

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