Japanese maples, branches dying

Asked January 19, 2020, 8:19 PM EST

Death is associated with a black area on the bark, with an orangey fringe. Photo attached. I suspect pseudomonas syringae? We are in Austin TX. This particular tree is Chisio Improved, but the same symptoms are infecting other trees in our grove. This one has the most damage.

Treatment possible?

Travis County Texas

11 Responses

When you say "other trees in our grove" are you implying that you have a grove of Japanese Maples or other trees? Are the leaves affected at all? (I realize it's winter but before the leaf drop.) When did this begin?

Thank you

Apologies for being misleading. What, don't you know what's growing in my garden? :) We have several (~8) Japanese maples under some live oaks. Before leaf drop, leaves withered, had some/subdued color, then shriveled brown. And then did NOT drop off the tree. My suspicion is.... the branch was dead or dying and the normal abcission process had been interrupted.

I wasn't studying the problem, but I suspect it began ~one year or more back. The one tree in the photo was very "underwhelming" in fall 2018, and clearly was not happy. I did not investigate so can't confirm that it's the same issue, but that's a reasonable assumption. It was the continued failure to thrive on this tree this fall that caused me to investigate thoroughly. I see traces of the same issue on at least three of the other trees. Oh, and one more datapoint - Chisio Improved is 15-20 years old.

Most obviously infected or dead branches have been pruned and trimmings removed. The particular tree in question I took 35% of the tree. :(

Because of the age, value and number of trees involved, I've reassigned this question to Dr. Ong, Texas A & M plant pathologist. If you don't hear back from him soon, please let us know.

Good luck

Thank you very much! Overall, we have about a dozen in that grove, three are quite young (planted last spring) and we have plans for two more, replacing some other plants. So figuring this out would be a good thing. :) I am much obliged, thanks for your attention.

Jim Trudeau.

Based on information above, my assumption:
All part above the lesions are dying or dead, multiple plants of the same type (maple) is affected & problem is not new but may have appears over 1 year ago.

While I cannot definitively say what caused the decline issue. Here is what I can tell you:
1. The lesion type in the photo would be more consistent with a fungal agent. If bacterial, specifically pseudomonas that you suggested - I would have expected a complain of water-soaked looking deteriorating leaves.
2. Understory trees can have challenges when it comes to nutrient sequestration. Is there a pattern that seems to suggest that older trees are more affected? Younger trees may not be as affected IF there is sufficient nutrient UNTIL there are of a certain size and has to compete for nutrients and water.
3. Can you recall as to when you suspected this might have happen? It is possible that there is some environmental trauma (or even physical trauma) that predisposed the trees to certain pathogen. Here would suggest submitting affected parts as well as root for diagnostic confirmatory analysis.
4. Check the roots, especially at the drip line. Some the accelerated senescing symptoms described could be due to damage and/or poor root systems. Simple check, look at ends and if root appear sloughed off, it may be a root rot issue.

Depending what the issues are, there is likely to be a probable solution.

Thank you Professor. I shall examine all trees to see if there is a pattern of appearance, and do a bit of digging at the drip line to examine roots. On ASSUMPTION, it is older trees. A fungal process gives me hope. :) Thanks again.

Professor, I was hoping to attach a zip file with multiple pictures, but that's not possible. So I'll pick representative damage. I examined roots for the Chishio Improved, and they appear OK to me (not a lot of experience on that). Found a significant root (pencil thickness), with several thin roots branching off, all looked fine. It extended well past drip line and dove deep, so I did not find the very end of the root.

I have thoroughly examined all the trees in the glade. All but one show signs of the same condition. The Coral Bark has never been a vigorous tree, and its general condition is about the same as always. Only the Chishio shows signs of failing. The concern is for the presence of whatever this is on so many trees.

In most cases, the disease is at a small branch, there is no sign of prior injury. The small branch dies and the infection spreads into the larger branch. For two trees there are spots on major branches, and on the trunk of the tree.

Variety Year Height Infection Health

Coral Bark 2004 10’ 2-3 small branches OK

Chishio 2005 10’ large branches, trunk Poor

Arakawa 2005 10-12’ 2-3 small branches vigorous

Brandt’s Dwarf 2006 3’ none vigorous

Fireglow 2007 10-12’ 2-3 small branches vigorous

Fascination 2007 10’ 2-3 small branches vigorous

Bloodgood 2008 10-12’ 2-3 small branches vigorous

Ryusen 2010 3’ 2-3 small branches vigorous

Shindeshojo 2011 10-12’ 3-4 large branches, trunk vigorous

Otome Zakura 2012 10-12’ none vigorous

Finally, a general overview of the woodland - 4-5 mature live oaks. 20 years ago this was grass. Under the oaks are mostly the maples, but also a redbud. There are other smallish understory trees along the property line - pittosporum, acuba. The woodland floor is decomposing leaf litter. The soil is soft and friable.

Finally, a general overview of the woodland - 4-5 mature live oaks. 20 years ago this was grass. Under the oaks are mostly the maples, but also a redbud. There are other smallish understory trees along the property line - pittosporum, acuba. The woodland floor is decomposing leaf litter. The soil is soft and friable.

You have a nice landscaped area. On the basis of the information you provided, here is what I would suggest:
1. Problem seemed localized. Prune out affected branches - at least 12-18 inches below damaged area. Look at the cross section - this is to make sure that the heartwood or vascular system is not rotted/dead. If it is, problem may be occurring further down. REMEMBER to clean pruning equipment between cut as a precaution and disposed of the pruning (away from your garden).

2. I do not think a treatment might be warranted at this time. However, monitoring would be important to note the progression and expansion, if any, of these symptoms.

As trees get older, they (like human) can become more conducive to colonization by other microorganisms. Also, if it appears that the lesion is localized - you can choose to submit specimens to the TPDDL for diagnostic analysis (if you do, please follow instruction for submission and include a representation/subsample of what you see - ie. good part as well as bad parts.)

Thank you very much. I'll be cataloging progress to see if newer lesions appear, and prune most if not all. For a couple of suspected lesions, we need to kill the tree, since the lesions are on the main trunk. I'm not quite ready to be THAT drastic. I'll wait to see if the tree as a whole starts to suffer. But we will be keeping a close eye.

Your help is greatly appreciated.