eXtension

Dying incense cedar tree

Asked July 30, 2019, 1:47 PM EDT

Hi. I have an incense cedar tree that has been browning from the bottom up for several years. I’ve talked with two arborists, but I’m getting conflicting information. I’m hoping you can help. Both arborists suggest doing annual fungicide injections. One of them wants to pair the fungicide with a fertilizer injection called Nutra Boost (it’s injected into the tree) starting immediately. The other wants me to fertilize twice a year with a fish oil fertilizer that I purchase myself. They both want me to water the tree. One says to use the soaker hose for 1/2 an hour every other day. The other says to water deeply (one inch) several times per week during hot spells. Less when the temps are more moderate. What do you suggest I do? I read an article from 2018 that mentions your advice. It said to water slowly for 6 hours every other week, and to fertilize in the fall, and didn’t mention any injections. I’m very confused. My incense cedar is about 22 years old. Approximately 6 feet around near base. I also have a red cedar that is similar age, and starting to show signs of stress. Some sap coming out of the bark. Thank you for helping me!

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Multnomah County Oregon forestry trees and shrubs urban forestry cedar incense cedar

12 Responses

Well, incense-cedar can get one of several canker diseases, which are fungal diseases that affect the branches. The symptoms on your tree do look similar to a branch canker, but the only way to tell if that is what is causing the dieback would be to prune off one or more affected limbs, and look for the cankers on the stem. Please see this link for more information:

You need to know whether this is truly a fungal disease before applying any fungicide, otherwise the treatment is pointless. Furthermore, it seems that the effectiveness of fungicides against these canker diseases is unknown. Did either of the arborists find canker on the branches?

Typically, these diseases affect trees that are a little weakened already, whether it's due to drought, poor soil, root damage, or other factors. We have been dealing with drought conditions since 2012, which could be a predisposing factor. I would NOT recommend fertilizing the tree while we are in a drought. Fertilizer will make the tree use more water, exacerbating the drought stress. Even if there is no fungal disease, poor growing conditions can make the tree lose branches. It's worth noting that while incense cedar is native to Oregon, it is not native to Multnomah County - so it's growing outside its home range which might also predispose it to stress.

Established trees like yours do not require watering as regularly as young trees, however, if the soil is particularly dry then providing a slow and deep watering can be helpful. Use a soil probe to see how dry the soil is. Often the top couple of inches will be dry but below that it will be moist. Mature trees can handle that. If not, then using a soaker hose just inside the dripline for a long while (the 6 hour suggestion is best), infrequently - like every other week when we have hot dry spells - will do.

Thank you for the info. Neither arborist mentioned canker disease. One of them told me that browning from the bottom up typically indicates a root disease. And that it was a fungal disease of some kind. He also said, the tree is shutting off growth to older branches while maintaining growth on newer branches.




He said that was a typical sign of root stress. As far as the Nutra Boost, he said it was ok to inject it directly into the tree even in hotter months. It’s only the in-ground fertilizers that make the tree need more water.
Also, they both said there’s no guarantee that the fungicide will help.

Yes, there is a root disease that affects Port-Orford-cedar. But it does NOT infect incense-cedar. You need to know which species it is that you have. They look quite similar but can be distinguished by the small cones that they produce. Incense-cedar cones look sort of like a ducks bill and are about 1 inch long, while Port-Orford-cedar cones are smaller, round and knobbly.
There are numerous fungicide injections registered for Port Orford cedar root disease:
So if you have Port-Orford and not incense cedar, then what these arborists are suggesting makes sense.

I’ve always been told it was an incense cedar. That’s also what one of the arborists called it. Unfortunately I don’t even remember seeing cones on the tree.

It’s hard to tell. But thanks for the additional link. Do you have an opinion after viewing the pictures?
Also, what did you think about Nutra Boost injections directly into the tree? The arborist said that only in-ground fertilizer makes the tree need more water.

I’m still hoping to hear what you think about Nutra Boost being injected directly into the tree?
But also, here is a close up picture of the cedar branch. It looks like Incense cedar to me. Wondering if you can tell?
Thank you!

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Hi, thank you for the photos. Yes, I agree that it looks like incense-cedar. So it is puzzling to me that the arborists think it is a root disease. I am unaware of any common root diseases that impact incense-cedar. I would ask them more about what specific root disease they think it has, and how they diagnosed it, before proceeding.

Sorry, I can't provide an opinion on Nutra Boost as I am not familiar with this product. I am not a certified arborist, I am a forester, and these types of products are rarely used in a forest setting. But, I wouldn't use it until you get a clearer idea of the specific diagnosis of this tree.

Thank you again. I'll contact the arborist to see what he says. The only thing he originally told me was that it was a fungal disease of some kind, and that it was in the roots. I think he thought that because it was browning from the bottom up. Neither arborist mentioned Canker disease.
It's very confusing to get so much conflicting information, even with the amount of water that's needed! I would love to save this tree, but I'm not feeling very confident that an annual fungicide injection is going to help. And knowing that Portland isn't the right climate for the poor tree makes me wonder if I should just have it cut down, and put it out of it's misery. I planted the tree when it was very small. They were giving them away while I was at Breitenbush. I also planted a maple tree, that ended up being too close to the cedar. I had it cut down last year in an effort to save the cedar. I guess it's possible that the roots got tangled/damaged because of how close the trees were to each other. But I really don't know.

I wouldn't give up on this tree just yet! Pruning out the dead limbs will make it look a bit scraggly, but not every tree can be perfect :)
Good luck.