American elm section

[Frax]

We removed some young American elms at a downtown condo in a park setting due to poor performance. One of the three was dead and the other two not far behind.

I snapped a quick image of this section.


elm section by altacal, on Flickr

The usual issue with American elms here is European elm scale. These elms probably had it at one point in recent years. They may have been injected for treatment with imidacloprid. This has been very helpful treatment for our elms. This scale can seriously ahrm elms.

But this one struggled anyway. Could this be infection following injection?

This is the setting, just for context. teh removed trees are not in this image.


urban elms by altacal, on Flickr

 

[Blinky]

Did the others have similar patterns?

 

[Frax]

This is the only one I noticed. Most of the sections are still in the back of the truck. I can take another look on Monday.

 

[robinia]

Maybe early slime flux?

 

[nuthin_special]

I don't know if that cross section tells enough of a story to diagnose. Poor performance? The growth rings look strong and consistent.

Can you use imidacloprid in Calgary?

The decay could be linked to trunk injections, that would make sense. If so i would think you could find the injection sites if you cut the log across right where they were made.

Maybe the harvestman in your picture killed them.

v

 

[Frax]

Imidacloprid was used possibly under a special order solely for micro injection for elm scale. I noticed the growth ring strength too. Including after decay. I am not sure this effect was responsible for the tree decline either.
There is a shadowing effect from this type othanf wounding. The cut does not have to pass right through the plane of initial wounding. KT can explain this better than I can.

 

[pcarborist]

Don't injectors typically inject on a buttress root flare? If so, do the points of infection in your cross-section photo, line up with buttress root flares on the stump?

 

[Frax]

This where I usually see them pc. This one was about a foot up from base. I don't know whether it as done poorly or whether shadow effect can be that far from source.

 

[KTSmith]

Definitely wound-initiated discoloration (WID) from holes drilled into the tree. Likely from injection, I don't know why else one would do that so symmetrically. A carefully placed ripping cut could go through the drill holes.
I don't see decay, just the WID. Of course, that's where decay will start, in the WID closest to the hole.
Looks like there may have been more than one round of wounding, separated by a year or two. Or maybe not, a good view of the radial face could answer that.
I'm not so sure about consistently good growth. I shouldn't say anything without a view of good, clean and sanded surface, but ring width seems to abruptly narrow outside of the the WID columns.
At what height was the disk collected?
Elms *do* form bacterial wetwood, of course. Wetwood discoloration usually is more round in cross-section and without the column boundary layers seen here.

 

[Frax]

Cut up all that elm yesterday. Didn't find another like this. I should have ripped the 'star' section. I can still do that, maybe tomorrow.
The 'star' section as about a oor from the base.
Thanks Kevin!