Chinese Elm and Black Spot

[Rodrigo]

I know that elms are very susceptible to fungus, especially black spot, so I've been trying to be proactive on this elm since I got it. I have been spraying it weekly with Daconil and Neem Oil and makeing sure not to water the foliage. I also try to remove the infected leaves as soon as I see them.
It's always had one or two yellow and black leaves on it at a time so I haven't been too worried but today I came home from work to find many more yellow leaves than usual. I'm worried that it's spreading now. The last time I sprayed it was this past Sunday. Is there anything else I can do/should be doing to control it better?


There are some leaves that aren't even yellow but they have black spots on them.


Thank you!

 

[Rodrigo]

No ideas on this from anyone? Every time I go outside there's lots more yellow and black leaves, which I remove. But then I come back the next day and there's more, to the point where I'll be running out of leaves soon if it keeps going like this! I'm also not seeing too much new growth, just here and there although it could still be getting used to the new location.

Compare the amount of leaves to the original picture, and it's only been a week!

 

[Gaston]

Up

 

[_#1_]

From my Google detective work, yellowing is from water stress. Either over or under watering. I have the same issue right now with one of my box store azalea. Will take care of that after it blooms and I find a bigger pot to slip it in.

Not sure how soil is on the elm but it's way deep in there. I would cut the pot down to soil level for light and air circulation. Air circulation mostly. I had a tree deep like that last year and the combination of shading canopy and deep pot made for perfect condition for all types of weird growths. Now I cut all my nursery acquisitions.

Speaking of, how's the air circulation and/or sun light it gets?

 

[Bonsai Nut]

I don't know who told you Chinese elms are very susceptible to fungus(?) Mine are bulletproof. If you are spraying weekly with Daconil and neem, I would be really surprised if this is a fungal issue related to environment.

Regardless, I think the issue may be with your roots (and water related problems) rather than random fungus infection. Where did you get your elm and how long have you had it? How long has it been in that pot? What do the roots look like?

 

[Rodrigo]

From my Google detective work, yellowing is from water stress. Either over or under watering. I have the same issue right now with one of my box store azalea. Will take care of that after it blooms and I find a bigger pot to slip it in.

Not sure how soil is on the elm but it's way deep in there. I would cut the pot down to soil level for light and air circulation. Air circulation mostly. I had a tree deep like that last year and the combination of shading canopy and deep pot made for perfect condition for all types of weird growths. Now I cut all my nursery acquisitions.

Speaking of, how's the air circulation and/or sun light it gets?

If that's the case I think it may be overwatering then.. I had a feeling it had something to do with water but the fact that there is black spots on the leaves was really throwing me off towards a fungus.

You're also right about it being way deep in the pot, I hadn't thought about how that may be a problem. I'll cut it down so it gets better circulation, thank you! It gets fairly good air circulation as is though since I live on the 3rd floor of an apartment building and it's sits on the ledge where there's always some wind. Sunlight could be better but it gets about 6/7 hours of afternoon sun. My balcony faces the west so I don't have morning light available. I'll keep an eye on the water and see if that helps

Thanks again for your help!

 

[Rodrigo]

I don't know who told you Chinese elms are very susceptible to fungus(?) Mine are bulletproof. If you are spraying weekly with Daconil and neem, I would be really surprised if this is a fungal issue related to environment.

Regardless, I think the issue may be with your roots (and water related problems) rather than random fungus infection. Where did you get your elm and how long have you had it? How long has it been in that pot? What do the roots look like?

I got it at a nursery near me that was having an auction through my local club because they were trying to liquidate everything about 2 weeks ago. I think it was one of the members that was there that day that told me but I don't remember exactly.
It came in the pot its in now with nursery soil and I haven't done anything to it except water and spray. I don't know how long it's been in the pot or anything.
I got it already in leaf and I haven't seen much new growth since then which I thought was weird. New leaves here and there but nothing else.
Here are the roots, I've wondered if I should put more soil on the exposed roots at the top or leave that for the next repot?
Thank you!

 

[Bonsai Nut]

Gently slip the elm out of that pot and look at the roots. The elm may have been slip-potted into that pot (do you see the inner cylinder of older soil, with a new circle of soil around the outside?) and it could have been in that pot for a long time - too long. It is probable that we will see the tree is extremely root-bound, and is in need of a re-potting.

 

[Rodrigo]

Gently slip the elm out of that pot and look at the roots. The elm may have been slip-potted into that pot (do you see the inner cylinder of older soil, with a new circle of soil around the outside?) and it could have been in that pot for a long time - too long. It is probable that we will see the tree is extremely root-bound, and is in need of a re-potting.

I pulled it out of the pot to take a look and cut down the top of the pot while I was at it. I didn't see any signs of there being an older cylinder of soil though. It could definitely use a repot but do you think it's bad enough to need a repot right now of out season?

 

[River's Edge]

I pulled it out of the pot to take a look and cut down the top of the pot while I was at it. I didn't see any signs of there being an older cylinder of soil though. It could definitely use a repot but do you think it's bad enough to need a repot right now of out season?
View attachment 191447View attachment 191448View attachment 191449View attachment 191450

It seems unusual for this time of year, but i see no new root tips. Is there any chance the tree has dried out or is still dormant. Was it shipped in from somewhere else recently? Perhaps you can see new root tips in the root ball. if there are none or very few then a repot may still be possible.
I would consider removing the obviously dead roots on the outside and breaking up the outside edges as a starting point. introducing new soil and better growing conditions where possible, if it does not interfere with actively growing roots.
Also it is reported that some chemicals will create phytotoxicity if used in conjunction with horticultural oils. Perhaps check on whether daconil is
one of those.

 

[just.wing.it]

Is it just me or does it look kinda dry??

How long have you had it??

I think this time of year, you should have long shoots everywhere.

 

[Bonsai Nut]

I didn't see any signs of there being an older cylinder of soil though.

Slip-potting is a common practice in commercial nurseries. A plant is grown to its maximum size in a small pot, and then it is "slipped" into a larger pot, and the pot is backfilled with fresh soil. This is fine for landscape trees, but bad practice for pre-bonsai, because the roots are never spread out, the old soil is never replaced, and the tree is left with a column of old soil and roots in the middle of the pot, with fresh soil and roots on the outside.

It often becomes noticeable because as the new soil in the larger pot settles, you can see the old outline of the old pot.

It is really important that you work towards not only repotting the new roots on the outside of the root ball, but you have to work your way into that column of old dirt. It probably is compacted and full of dead roots. When you water your tree, that core may not be getting watered - the water may flow around the outside of the packed center and flow around the outside of the root ball.

When you repot your bonsai you need to get rid of ALL the old soil and open up the root ball. It may not always be possible when you have a rootbound weak tree like yours. But you have to know what direction you are working towards - you have to get into the old dirt.

 

[Rodrigo]

It seems unusual for this time of year, but i see no new root tips. Is there any chance the tree has dried out or is still dormant. Was it shipped in from somewhere else recently? Perhaps you can see new root tips in the root ball. if there are none or very few then a repot may still be possible.
I would consider removing the obviously dead roots on the outside and breaking up the outside edges as a starting point. introducing new soil and better growing conditions where possible, if it does not interfere with actively growing roots.
Also it is reported that some chemicals will create phytotoxicity if used in conjunction with horticultural oils. Perhaps check on whether daconil is
one of those.

Yeah it's definitely unusual that there's no new tips, and I guess that would explain why there really isn'tmuch growth either. It wasn't shipped, I got it at a physical bonsai nursery only about a couple weeks ago. I've read on other posts on here that slip potting from nursery soil to bonsai soil isn't always good because of the water running down the bonsai soil and not into the old soil, and since I didn't know if I should do a complete repot right now I haven't done anything. I'll look into phytotoxicity also, I've never heard of that. Thank you!

 

[Rodrigo]

Is it just me or does it look kinda dry??

How long have you had it??

I think this time of year, you should have long shoots everywhere.

It is a little dry in the pictures but that's because I've been letting it dry it out just a bit since the general consensus is that it's overwatering that's causing the yellowing. I've only had it for a couple of weeks so I'm still getting used to watering the type of soil it's in. I've had Chinese elm in the past and you're right, it should be booming right now

 

[Rodrigo]

View attachment 191511

View attachment 191513

Slip-potting is a common practice in commercial nurseries. A plant is grown to its maximum size in a small pot, and then it is "slipped" into a larger pot, and the pot is backfilled with fresh soil. This is fine for landscape trees, but bad practice for pre-bonsai, because the roots are never spread out, the old soil is never replaced, and the tree is left with a column of old soil and roots in the middle of the pot, with fresh soil and roots on the outside.

It often becomes noticeable because as the new soil in the larger pot settles, you can see the old outline of the old pot.

It is really important that you work towards not only repotting the new roots on the outside of the root ball, but you have to work your way into that column of old dirt. It probably is compacted and full of dead roots. When you water your tree, that core may not be getting watered - the water may flow around the outside of the packed center and flow around the outside of the root ball.

It is really important when you repot your bonsai to get rid of ALL the old soil and open up the root ball. It may not always be possible when you have a rootbound weak tree like yours. But you have to know what direction you are working towards - you have to get into the old dirt.

Welp. Shit. LOL I've always heard that nurseries do that but I'd never seen an actual example myself. I was looking a bit further down the pot, I thought what you highlighted was that the pot tipped over at some point and the top layer had fallen off. You're right though, I do struggle to get the water to not slide off the mound even though I try my best to.
Do you recommend that I bare root right now though? Like I told @Riversedgebonsai, I didn't know if I should slip pot or repot so I hadn't done anything at all yet. The nursery it was at was outdoors so I'm pretty sure it's not dormant any more and those leaves are from this spring.
Thanks for your help!

 

[River's Edge]

Welp. Shit. LOL I've always heard that nurseries do that but I'd never seen an actual example myself. I was looking a bit further down the pot, I thought what you highlighted was that the pot tipped over at some point and the top layer had fallen off. You're right though, I do struggle to get the water to not slide off the mound even though I try my best to.
Do you recommend that I bare root right now though? Like I told @Riversedgebonsai, I didn't know if I should slip pot or repot so I hadn't done anything at all yet. The nursery it was at was outdoors so I'm pretty sure it's not dormant any more and those leaves are from this spring.
Thanks for your help!

IMHO you have nothing to lose at this point. If it was mine i would go for it. Be as careful as possible, workf slowly with a chopstick and mist the roots as you go. Keep anything that is alive, discard all dead or rotten roots. Make sure you get the core. Place new soil carefully around and between the remaining roots, tie in the pot. Let pot soak in a basin for five minutes to ensure the whole root ball is wet after the process. Good luck

 

[_#1_]

general consensus is that it's overwatering that's causing the yellowing

I think it could be under watering too. Do everything feel tight and compacted? Once you had the tree out the pot you could of test and water from the middle and see if it runs down to the side.

This is my plan for my REALLY compacted azalea ( I can't recommend you do the same with your elm since they're different)

After flowers, trim.
Pop it out the pot.
Use chop stick to loosen about half or one inch of outer rootball.
submerge entire rootball in a bucket or wash tub for about 15/20 minutes hoping water will penetrate to the center.
Put into pot one size larger and backfill with 60/40 soil conditioner (composted pine bark) and whatever I have laying around, mostly mix of potting soil, lava, 8822, pumice.
Then place along north side of house.

This has worked well for me in last year with all my deciduous so I'll try it on the Azalea too.

 

[River's Edge]

I think it could be under watering too. Do everything feel tight and compacted? Once you had the tree out the pot you could of test and water from the middle and see if it runs down to the side.

This is my plan for my REALLY compacted azalea ( I can't recommend you do the same with your elm since they're different)

After flowers, trim.
Pop it out the pot.
Use chop stick to loosen about half or one inch of outer rootball.
submerge entire rootball in a bucket or wash tub for about 15/20 minutes hoping water will penetrate to the center.
Put into pot one size larger and backfill with 60/40 soil conditioner (composted pine bark) and whatever I have laying around, mostly mix of potting soil, lava, 8822, pumice.
Then place along north side of house.

This has worked well for me in last year with all my deciduous so I'll try it on the Azalea too.

That is the exact process that created the problem in the first place. Short term relief for long term pain. In the end the compacted soil must be removed, it will only get worse. The objective is different from gardening the rootball needs to be developed for a Bonsai in a pot. Killing off the core of the rootball does not accomplish that.

 

[_#1_]

That is the exact process that created the problem in the first place

Ah yes, forgotten to add. This process is for trying to induce new roots and stay healthy till next year when you can do a real repot at the right time. I thought it would be dicey to play with the roots when leaves are hardened. If my azalea do well enough after the slip pot, it'll get a real repot next spring. (edit) It will get a real repot no matter what. Rootball is a brick!

I still have a whole lot to learn myself so I'll be following this process...

 

[LanceMac10]

Mine? I'd stop with all the sprays. Root prune hard, bareroot and rinse crap soil out. Good soil in an appropriately sized container. Hell, I might even defoliate and stick it in the shade for a couple weeks.

Probably overwatering....most of the problems you run into just starting out are directly related to watering habits.

No slip potting, it's like putting a dirty bandage on a cut!! No benefits!