Repotting Maples for Fungus/Health

[MrG]

Hey B Nuts,

I acquired two trees from a nursery owner recently - a Trident and a dwarf JM. Both are in nursery pots and organic (I believe entirely) soil. Both of them are having fungus issues. My instinct is telling me that it’s related to the soil and essentially pot health… So my question is, in what scenario would one slip pot a maple into a more breathable/free draining container, etc. well into the growing season such as now?

I have read @Smoke ‘s fine posts on maples and tried to surmise the relevant advice, but I’m just not sure what that would be. If it’s between the trees suffering, treating the symptom, and righting the inherent cause, I’m not sure which is the best path.

Photos below of the fungal situation:




I truly appreciate any insights in advance!

All best,
MG

 

[Shibui]

I suspect there's more here than just fungal issues as a result of organic soil.
The trident has yellow leaves typical of deficiency, probably Nitrogen but also possible Fe, Mg, or other micro nutrient deficiency or a combination.
Problems associated with organic soil is always related to watering. If you match your watering to the soil there should not be a problem.
Slip potting a fully organic soil into a fully inorganic soil is likely to have negative results. Neither roots or water cross such a boundary easily so many slip potted plants end up with more problems than before.
Review your fertilizer program and adjust to suit the watering and soil conditions to see if that helps.
Adjust watering regime to suit the soil.

 

[bwaynef]

My initial thought was this could be nutrient lockout due to high pH. A couple waterings dosed w/ vinegar would be telling.

 

[MrG]

Thank you all! @Shibui your point is very good and will continue to try to adapt my watering. I’ve been doing this but Nashville, TN has been having a particularly soggy period which hasn’t helped.

However, my apologies for not being thorough enough on one point. The trident is a specific cultivar (“Michael Steinhardt”) that is yellow and turns to orange, so my understanding is that the yellow color is “correct”. The issue with the trident is larger brown spotting.



The JM has smaller and more brown spots.


Curious if that changes any thoughts. I have been applying Biogold and I am limiting water to once a day at most, and propping them up on angle. I also cut more large drainage holes into the bottom of the nursery pots… I’m not sure what I can do to get these pots and soil drier more consistently.

Thank you!
MG

 

[Paradox]

Thank you all! @Shibui your point is very good about and will continue to try to adapt my watering. I’ve been doing this but Nashville, TN has been having a particularly soggy period which hasn’t helped.


Curious if that changes any thoughts. I have been applying Biogold and I am limiting water to once a day at most, and propping them up on angle. I’m not sure what I can do to get these pots and soil drier more consistently.

Thank you!
MG

If it's been that wet, are you sure they need watering once a day currently?

Have you tried the chopstick method to monitor wetness of the soil?

Stick a wooden chopstick in the pot and leave it there. Take it out once a day and look at it/feel it. The tree needs water when the stick is almost dry. Don't allow it to get completely dry.

 

[MrG]

If it's been that wet, are you sure they need watering once a day currently?

Have you tried the chopstick method to monitor wetness of the soil?

Stick a wooden chopstick in the pot and leave it there. Take it out once a day and look at it/feel it. The tree needs water when the stick is almost dry. Don't allow it to get completely dry.

Thanks @Paradox ! Yes I think you’re right, and I have been water only every other day at times. But I haven’t tried the chopstick method as I’m comfortable with wateting habits of all my other trees - I’ll try that so I can get a handle on what’s happening in the pot.

MG

 

[bwaynef]

The trident is a specific cultivar (“Michael Steinhardt”) that is yellow and turns to orange, so my understanding is that the yellow color is “correct”.

My nutrient lockout comment was due to the trident's color. I have heard pH can lead to issues with tridents, but not exactly how the issue is presenting with your trees. I suspect this is fungal in nature. I noticed significantly less fungal issues after I began dormant spraying. That's probably out of the picture for you right now, but a broad-spectrum fungicide may get this under control.

 

[Wires_Guy_wires]

I have heard pH can lead to issues with tridents, but not exactly how the issue is presenting with your trees.

It would explain the typical calcium deficiency spots on the foliage of the green one.
Either too low of a pH (usually occurs when overwatering for a long time: fermentation happens, which acidifies the soil) or too high of a pH that causes lockout of basically all metals, leading to chlorosis. Root death however, can have the same symptoms, and can be caused by both.

 

[MrG]

Thanks all - definitely noted and seeing the trends here.

I have been thinking that perhaps I need to get my water tested. I’ve heard that Nashville has a sort of filtering to the water supply, so perhaps it is nutrient deficient. Maybe I should add Calmag?

Is it worth noting that other trees of mine are not exhibiting many issues at all, and have good growth and traits? Or are maples just more prone to notice these mineral deficiencies/ph issues?

And these may have had too much water for a long time, however, I have not been watering much at all since I’ve had them in my care comparatively. Definitely trying to dry them out.

All best,
MG

 

[MrG]

My nutrient lockout comment was due to the trident's color. I have heard pH can lead to issues with tridents, but not exactly how the issue is presenting with your trees. I suspect this is fungal in nature. I noticed significantly less fungal issues after I began dormant spraying. That's probably out of the picture for you right now, but a broad-spectrum fungicide may get this under control.

Meant to also add that I am applying Bonide granular now, although I would much prefer to resolve the root cause (pun intended) rather than treat the symptom.

 

[Orion_metalhead]

I would monitor watering and prepare for a repot into inorganic or an airier soil substrate in late summer/fall with little or no root reduction. Given your southern climate, I dont think it would be as risky as leaving the trees in waterlogged soil.

Dormant spray in winter. Treat with a systemic like 3in1 in spring as growth starts.

if your other trees are fine and not suffering, they should pick back up no problem.

 

[MrG]

I would monitor watering and prepare for a repot into inorganic or an airier soil substrate in late summer/fall with little or no root reduction. Given your southern climate, I dont think it would be as risky as leaving the trees in waterlogged soil.

Dormant spray in winter. Treat with a systemic like 3in1 in spring as growth starts.

if your other trees are fine and not suffering, they should pick back up no problem.

This is definitely the direction I’m thinking. A few questions:

In terms of signs of when it’s safe to try a repot, what am I looking for? Before leaf drop or no?

Regarding container, they’re both in like 2 or 4 gallon nursery pots, so if I do minimal or no root reduction, I’m afraid I’ll have to repot them into a pretty huge potentially depending on roots of course. Would I just do it anyway and fill it all the way up with inorganic quality bonsai substrate?

Thanks much,
M

 

[Orion_metalhead]

Deciduous trees put on roots in fall as they gear up to store energy for winter.

I notice they bulk up from mid sept through november. I would feel safe with a light repot from the end of Aug until middle of Sept.

Regarding pot size, I would prepare to do a light trim around the circumference of the tree. I would have an appropriately sized grow box ready, possibly 4" deep by 1.5 times the diameter of the current pot. Once the bad soil is removed, I would spread the roots out and trim only what is exceptionally long and outside the box. Any light reduction on downwards roots could possibly also be done safely if there are good radial roots.

This kind of repot should not be difficult if you have some previous experience with repotting out of nursery soil. Id make a grow box like these out of scrap wood:

 

[MrG]

Deciduous trees put on roots in fall as they gear up to store energy for winter.

I notice they bulk up from mid sept through november. I would feel safe with a light repot from the end of Aug until middle of Sept.

Regarding pot size, I would prepare to do a light trim around the circumference of the tree. I would have an appropriately sized grow box ready, possibly 4" deep by 1.5 times the diameter of the current pot. Once the bad soil is removed, I would spread the roots out and trim only what is exceptionally long and outside the box. Any light reduction on downwards roots could possibly also be done safely if there are good radial roots.

This kind of repot should not be difficult if you have some previous experience with repotting out of nursery soil. Id make a grow box like these out of scrap wood:

View attachment 549420
View attachment 549419
View attachment 549418

Thank you very much for all this! I am experienced with repotting so no big worries. You definitely answered my main question just regarding how to logistically handle the root mass gently enough not to shock the tree while also getting it into a new vessel.

I’ll aim to do this near the end of August and I’ll update this thread when I do!

All best,
MG

 

[MrG]

Ok so today I found a very strange looking leaf symptom on the Trident, and wanted to post it here in hopes I can understand more of what’s going on with this tree.


This is like a silvery, grey, almost metallic looking spot. No changes in care to speak of. I hope this is all business as usual for maples to some degree. As mentioned I am new to maples, and I really don’t want to lose this tree specifically.

MG

 

[MrG]

Alright, false alarm on the grey. I believe some wound putty melted off, my fault.

@Shibui I have a question if you’d be so kind:

You mentioned not repotting into inorganic surrounding media as the roots wouldn’t know what to do… When I first got the tree I topped it off with probably 1-2 inches of bonsai soil on top of its nursery soil. I’m wondering if this is the cause of confusion for the surface roots, or if the moisture is somehow being trapped, etc., and if this is causing a problem. Do you think it could be? Should I remove the top bonsai soil?

Thank you very much again,
MG

 

[Shibui]

Hard to comment on a tree I can't see or feel but it has often been reported that different soil mixes can cause problems with water. I've experienced it myself. Sometimes all the water you add just runs through the new, coarse outer soil and the older, inner soil where the roots are gets progressively drier until the tree dies. Occasionally the opposite can happen and the older soil gets wet and the water can't move out into the new, coarser soil.
I guess you will need to do some excavation to see what's happening in your pot. It may be perfectly OK or it may not.

 

[MrG]

Hard to comment on a tree I can't see or feel but it has often been reported that different soil mixes can cause problems with water. I've experienced it myself. Sometimes all the water you add just runs through the new, coarse outer soil and the older, inner soil where the roots are gets progressively drier until the tree dies. Occasionally the opposite can happen and the older soil gets wet and the water can't move out into the new, coarser soil.
I guess you will need to do some excavation to see what's happening in your pot. It may be perfectly OK or it may not.

Thank you @Shibui ! I hear you on that. I’m really just trying to sort through the potential logic here.

I think the main symptoms I’m noticing is the combined presence of too much water (fungus, chopstick wet) and also leaves feeling a bit paper dry.

All I did when I got the tree was put that top fill of bonsai soil (1:1:1) and prune back running growth. So I’m thinking maybe (as you said I believe) the roots on the top of the soil think they’re hitting air when it’s really aerated bonsai soil and so they’re somehow unable to absorb the water they are getting properly.

I’ll try removing topsoil. What would you suggest I’d be looking for when excavating?

Thank you very much,
MG

 

[MHBonsai]

Nashville resident here…come to the NBS meetings if you can! Looks like root problems to me. Very possibly too wet with what our weather has been doing.

Check water PH as well. Mine rides at about 8-9+ which is enough to lock up growth for a lot of maples and others unless you adjust for it.

 

[Deep Sea Diver]

Not sure about the root issue. Definitely a fungus issue.

A couple practical things one might do right now.

• Get the tree out of the rain for awhile and let it dry out more,
• Don’t water until this happens (drying)
• Spray with copper top and bottom of leaves (only).
• Chock up one side of the pot to give sharper drainage
• Take a 3/16” drill and driver, then drill a patchwork of holes around the sides at the bottom 3-4” of the nursery pot. This will increase drainage.
• Use a slow release fertilizer like Osmocote Plus, 1/2 recommended strength, and consider giving a couple applications of Miracle Gro (1 per two weeks) to quickly strengthen the tree. Both these will help right away with nutrient issues. (Although the nursery soil ought to help buffer water issues.

Finally, please go and visit the Nashville NBS folks. WhileI’ve spent a good deal of time working around Oak Ridge over the years, it’s best to take the time to be with the folks who really know the tree horticulture in your area.

Just some thoughts.

Cheers
DSD sends