What's wrong with my collected American elm?

[pitchpine]

So, I collected this multiple trunk elm on April 16 just as the buds were starting to swell. It was growing on the edge of the sidewalk in front of my parents house, so I was able to only save a small fraction of the roots. I was completely out of bonsai soil at the time (it was a spur of the moment decision to collect it before it got hacked back again this year) so I planted it in a small colander in a mix of potting soil and artificial pumice.

Up until late last week it's been doing fine, but now it's starting to get yellowing on some of the new leaves, mostly at the top of the tree but also near the bottom of one of the smaller trunks. Any ideas what the problem may be, and what I can do?

 

[AZbonsai]

I think if it was going to die from transplant it would have done so by now. Yellow leaves can mean a nutrient deficiency. It has been 3 months since transplant maybe hit it with some miracle grow. How well does it drain?

 

[pitchpine]

It drains fairly well because of the pumice, but also holds a lot of moisture because of the organic stuff. When I've got the pot in full sun it seems to dry out almost completely every day. I've moved it to a shadier location since the yellowing started but now I'm afraid it's staying wet too long.

The leaves that were yellowing when I took those pics Saturday have now turned completely yellow and fallen off. Do you think fertilizing it lightly now would be safe? I've sprayed the tree a few times each with liquid copper and pyrethrin but have been afraid to fertilize in its weakened state

I think if it was going to die from transplant it would have done so by now. Yellow leaves can mean a nutrient deficiency. It has been 3 months since transplant maybe hit it with some miracle grow. How well does it drain?

 

[AZbonsai]

Did it have bugs? I have Chinese elms I know they throw some leaves every once in awhile. The other leaves look pretty healthy...I think you could try a bit of fertilizer just don't go over board.

 

[pitchpine]

This one didn't have bugs that I could see, but there could have been some spider mites. And the other tree I collected from the same area that same day had a little bit of scale, so I figured better safe than sorry!

I'll give it a light application of fertilizer and cross my fingers, thanks!

Did it have bugs? I have Chinese elms I know they throw some leaves every once in awhile. The other leaves look pretty healthy...I think you could try a bit of fertilizer just don't go over board.

 

[bonsaichile]

Maybe it is a root issue. I had an Amur maple that died because I was too extreme in pruning its roots. It began with the same symptoms: buds elongated, pushed new leaves, everything looked normal, and one day the new growth started to yellow out and then it died. The tree soon followed suit. You mention that you could not get a decent amount of roots when you dug it up. That might be the culprit

 

[chansen]

I'd be surprised if it were a nutrient deficiency since it's in an organic mix. Could be, but less likely. It could also be overwatering, or mites. I've never had an American elm, and haven't lived in Boston, so I'm not sure what pests they are prone to in your area.

 

[M. Frary]

I'd fertilize it.
I have elm leaves turn on me every so often.
I don't even notice anymore if they are a nice yellow but if they just turn brown and fall off then I worry.
Also get it out into full sun. Don't baby it. It's an elm.
And quit hitting it with pesticides.