Dieback on Sharp's Pigmy?

[99 Mile Creek]

I finally got ahold of a Sharp’s Pigmy. Unsure if I should start trimming back or not, I put of that on hold till I could do a little more research (pretty sure winter/early spring is best for major pruning?) and decided to get rid of the dead branches.

When removing the dead foiling, I noticed it was not only dead in some places, but jet-black dead. I thought maybe this is dieback from damaged branches at first. Then thought it might be root rot. Wasn’t sure.

I repotted it in some bonsai substrate to introduce more oxygen to the roots. And there was some root rot. Nothing significant that didn’t get reduced in order to fit into the pot.

My question would be, is the dead black foliage on a Sharp’s Pigmy a result of root rot, or is it die back, similar to other trees like a BRT? Or is it a fungus I should be spraying for?

I think this is out of the window for pruning? From what I gather, I should probably look to reduce this quite a bit—being a long-term investment sort of thing—but also gradually so as to not shock the tree?

Any and all advice on the Sharp’s Pigmy, I’m all ears. Really glad I was able to find one at my local nursery this year. Thanks

 

[Jrmcmich]

Can’t answer some of the questions you have as I dont have experience with that one but do wonder if you might want to cover surface roots better?

 

[99 Mile Creek]

Can’t answer some of the questions you have as I dont have experience with that one but do wonder if you might want to cover surface roots better?

I hesitated part way through taking the roots off, wondering if it was root rot or some other fungus. I ended up taking as little as possible. If it turns out to be nothing, I'll reduce it a little more.

 

[99 Mile Creek]

Took better photos:

 

[radhatter]

I’m no expert but I do have one of these and the dieback definitely doesn’t look like this. Typical gray on mine when it does happen. Could be root rot or a fungus.

So far I’ve found mine respond well to the care schedule of any other Japanese maple. I did successfully get hardwood cuttings to take off it last fall too.

 

[Deep Sea Diver]

Sure looks like Pseudomonas syringae, common in maples. Usually happens out here when folks prune in thrainy fall and go not properly disinfect and seal the wounds.

Treatment - none. Solution cut back below black areas, leaving space for the green to dieback properly to next green. Be sure to disinfect with alcohol and seal all wounds.

Sometimes one ends up chasing this back improperly and it gets into the trunk… then it’s a bigger problem.

Good luck
DSD sends

 

[radhatter]

Sure looks like Pseudomonas syringae, common in maples. Usually happens out here when folks prune in thrainy fall and go not properly disinfect and seal the wounds.

Treatment - none. Solution cut back below black areas, leaving space for the green to dieback properly to next green. Be sure to disinfect with alcohol and seal all wounds.

Sometimes one ends up chasing this back improperly and it gets into the trunk… then it’s a bigger problem.

Good luck
DSD sends

When you say disinfect with alcohol, do you mean the cutting tools or the cuts themselves?

 

[Deep Sea Diver]

Good question.

Both!

Cheers
DSD sends

 

[radhatter]

Good question.

Both!

Cheers
DSD sends

Interesting! I would have assumed that the alcohol would damage cell walls but I guess you’ve already done a pruning cut, so the disinfection is probably more beneficial than the damage it might cause.

 

[Deep Sea Diver]

So the cells should dissicate after pruning. The sealer is to lessen the chances of reinfection if the alcohol doesn’t do the complete job.

Cheers
DSD sends

 

[99 Mile Creek]

Sure looks like Pseudomonas syringae, common in maples. Usually happens out here when folks prune in thrainy fall and go not properly disinfect and seal the wounds.

Treatment - none. Solution cut back below black areas, leaving space for the green to dieback properly to next green. Be sure to disinfect with alcohol and seal all wounds.

Sometimes one ends up chasing this back improperly and it gets into the trunk… then it’s a bigger problem.

Good luck
DSD sends

Not saying I'm not up for the challenge, but this is highly contagious for my other trees, no? Will quarantine for sure and contact nursery.

Looking into this, it appears that people have been using a H2O2 treatment. Has this method been disproven? Maybe I should treat all my trees with a preventative? That's what I'm most concerned with.

Thanks for the feedback.

 

[Bonsai Nut]

I agree with the pseudomonas diagnosis, but to be honest, pseudomonas is a symptom and not a cause. Pseudomonas is a bacteria that is widely present in soil - particularly soil with organic components that include compost or animal manure. Japanese maples are not particularly strong trees; pseudomonas infections can be brought on by:

(1) Repotting at the wrong time of year - soil bacteria is more active during warm months.
(2) Cutting roots and repotting into organic soil.
(3) Allowing soil to stay too wet, particularly with organic mixes.
(4) Not sealing pruning wounds, and/or working the tree with tools that are dirty or have been in organic soil. This category includes heavy watering of foliage immediately after pruning (water the soil only).
(5) Japanese maple air-layers where the bottom of the air-layer was not sealed before being planted.

The tell-tale sign is black on the bark, and the foliage suddenly wilting / crashing. Other parts of the tree look perfectly healthy and show no signs of distress or fungus.

Usually the only solution is to stop doing what you did to cause the infection, remove the infected parts of the tree, and get the tree as healthy as possible. There are systemic antibiotics that can be used to fight the infection, but they will only limit the spread of the bacteria - and will not reverse the damage already caused. Make sure you do NOT prune the diseased parts of the tree and then continue to use your tools on healthy parts of the tree (or other trees) without disinfecting. Additionally, this is one case where you should collect your pruned infected branches and dispose of them in garbage. Do not compost them or toss them in a green waste container.

Think of your Japanese maple like a human body, and there is no way you would do surgery on a human body without disinfecting tools and closing up the wound afterwards. At least... I hope not

 

[99 Mile Creek]

Usually the only solution is to stop doing what you did to cause the infection

I just purchased this yesterday. Not sure what the tree's history is beyond the nursery. Never had issues with maples purchased form this nursery either. So maybe this will give them a heads up.

Additionally, this is one case where you should collect your pruned infected branches and dispose of them in garbage. Do not compost them or toss them in a green waste container.

This really makes me worry for my other trees... I would be more comfortable if this wasn't around my trees at all. I just called and am waiting on a response.

All that is great advice, though, thank you. If this stays with me, I'll be very careful with this one.

Other parts of the tree look perfectly healthy and show no signs of distress or fungus.

It does look healthy! But there are a lot of areas where that green foliage is coming out of an already-blackened stem -- well past the node. A lot of what is green now will soon be black. Looks like I picked this up at the wrong time.

All this is uncharted territory for me. I think I'll get a H2O2 solution ready and spray the trees on the bench it came in contact with and then quarantine those.

 

[penumbra]

One: I use 70% drugstore alcohol frequently on my plants with no damage.
Two: Peroxide is my go to to help spread of pseudomonas.
Three: It is not a disease we commonly bring home from the nursery. It is there waiting and it is widespread and commonly waiting in the shadows.

Bonsai Nut has covered it pretty well.

 

[99 Mile Creek]

One: I use 70% drugstore alcohol frequently on my plants with no damage.
Two: Peroxide is my go to to help spread of pseudomonas.
Three: It is not a disease we commonly bring home from the nursery. It is there waiting and it is widespread and commonly waiting in the shadows.

Bonsai Nut has covered it pretty well.

Thanks for the input again. Sorry multiple posts...

It definitely makes me appreciate sanitizing tools. Something I've always read, but never really saw why. With this, I can see.

Glad I caught it as I brought it home. This could have been worse.

 

[Bonsai Nut]

It does look healthy! But there are a lot of areas where that green foliage is coming out of an already-blackened stem -- well past the node. A lot of what is green now will soon be black.

Not necessarily. A healthy tree has its own defenses against infection. I have over 50 Japanese maples growing in close proximity to one another. I have had trees that come in, lose a single branch to pseudomonas for one reason or other, and then recover and never get it again. Sometimes it will be a single branchlet on an otherwise healthy branch. I have had it show up on trunks of landscape trees when they were damaged as part of the transportation/planting process. I simply removed the diseased bark, cut back to healthy bark, then treated the wound site with lime sulfur and sealed the margin of the wound with cut paste. I have had good luck with this treatment, and the trees have gone on to heal the damage.

 

[Deep Sea Diver]

Great replies folks!

Here is an article from Michael Hagedorn to help fill in any gaps. Michael does recommend some treatments that are effective, but hazardous, like Zerotol, which is amped up H2O2. It is effective bit hazardous for use and especially if improperly stored. Boom!

That said… lurking in the shadows….

Cheers
DSD sends