A Palmatum seedling - yellow patches and minute black spots on leaves

mdsai

Seedling
Messages
6
Reaction score
1
Location
St Louis, Mo
USDA Zone
6b
I harvested a 2-leaf stage new seedling this summer from under a Bloodgood JM: appears to be Acer palmatum, or Acer palmatum ‘Atropurpurpeum’ seedling. Managed reasonably well in the wet/hot St Louis summer, but I just noted yellowing patches on some leaves (one possible cause is morning sprinkler exposure which I stopped) - - took a photo and higher magnification shows minute black spots - therefore suspect fungal, potentially early lesions of Anthracnose, Phyllosticta, or Tar Spot - will see what develops. I know Neem oil may injure maples and this is a young unhardened seedling, but opted to spray with dilute Neem concentrate 1Tbsp per gallon and keep in shade away from sprinklers. Any ideas re the cause - am I on the right track? Neem seems a general coverage if the seedling will tolerate - I may consider change to pyrethrin/sulfur spray or a copper fungicide spray if Neem adversely affects the leaves in the days ahead or if the involved areas worsen. Should I remove involved leaves – upper, newer leaves have no lesions yet. Just attempting the challenge of raising a maple bonsai from natural new seedling harvest.
 

Attachments

  • MapleSeedling1.jpg
    MapleSeedling1.jpg
    114.2 KB · Views: 48
  • MapleSeedling2.jpg
    MapleSeedling2.jpg
    79.9 KB · Views: 46
  • MapleSeedling3.jpg
    MapleSeedling3.jpg
    111.8 KB · Views: 55

TN_Jim

Omono
Messages
1,534
Reaction score
1,630
Location
Nashville TN
USDA Zone
7a
Looks fungal. I’d try something like daconil.
This is interesting:
 

0soyoung

Imperial Masterpiece
Messages
6,797
Reaction score
11,156
Location
Anacortes, WA (AHS heat zone 1)
USDA Zone
8b
First, this isn't a palmatum, despite where you found it. It looks like a red maple (acer rubrum) to me. It could be yet a different maple, but the red petioles are the tell-tale characteristic responsible for the species name.
Second, I'm suspect this is bugs as opposed to a fungus.

Nevertheless, if it is fungal, the SOP for fungus is to remove the infected leaves (they are just a source of spores for further infection) and spray. I use a solution of 2 tablespoons 3% hydrogen peroxide (from the grocery/pharmacy) in a quart of water. It is a broad spectrum antiseptic.

Inspect the pictured leaf before you dispose of it. Do the little black dots rub off? Do they run around?

Meanwhile, if you have NEEM on hand, carefully spray one leaf to test NEEM compatibility. If it is harmful, the treated leaf should show some kind of negative reaction within a few days -- withering, discoloring, etc. Bear the results of this simple test in mind for prospective future use on this plant. NEEM is good for sucking insects, including whitefly and does act on many fungi.
 

BonsaiNaga13

Shohin
Messages
423
Reaction score
304
Location
St. Louis, Missouri
USDA Zone
6b
Glad to see more St. Louis ppl into bonsai, but like osoyoung said that's not an Acer palmatum. If the species isn't suitable for bonsai I'd just let whatever happens happen and collect some Japanese maple seeds to have something to mess with next year.
 

mdsai

Seedling
Messages
6
Reaction score
1
Location
St Louis, Mo
USDA Zone
6b
Obviously, I am a neophyte - approx 20yrs ago worked a number of years with some starter trees (Ginkgo, Pomegranate, and a nursery stock maple which ended up in the ground) and decided to re-engage -> picked up a ~5yr Ginkgo and ~5yr Full Moon Aureum this summer.
Have little prior experience with bonsai maples - maple varieties in general, never tree seedlings (the long timeframe); this seedling has taught me a lot this summer - and now the lesson from my outdoor harvest: don't assume a seedling's ID or variety based on proximity to another tree --- and then variety hybridization. Agree, looked at maple seedling photos on the web - clearly doesn't look a palmatum. The nearest maple in the neighborhood is a Sugar Maple - web photo comparison doesn't quite match, and thanks re the point of the red petioles -> Red Maple possible - lesson learned, I still won't assume at this point. I may continue to grow the seedling for experience/education - depending on what evolves; but will be cautious with fungus persistence and increased risk of cross contamination. I accept this as more an indicator of risk to other plants, and a chance to learn prevention.
The black dots do not wipe off, don't move around - are so small to the naked eye, I used my macro lens to photo and get closer look. Will test the Neem; if the seedling hangs in there may Daconil
Thanks re the Hydrogen peroxide.
 
D

Deleted member 21616

Guest
@0soyoung just for my (and others') general knowledge, can i please ask if a tree, or specifically a palmatum, can ever be "cured" of a fungal infection (whether it be a seedling or a mature decades-old bonsai), or does the infection remain 'inside' the tree forever? i'm being vague here because i'm out of my depth

Thank you!
Derek
 

0soyoung

Imperial Masterpiece
Messages
6,797
Reaction score
11,156
Location
Anacortes, WA (AHS heat zone 1)
USDA Zone
8b
@0soyoung just for my (and others') general knowledge, can i please ask if a tree, or specifically a palmatum, can ever be "cured" of a fungal infection (whether it be a seedling or a mature decades-old bonsai), or does the infection remain 'inside' the tree forever?
The simple answer is no.

That is the reason for the fungus Standard Operating Procedure to remove the infected tissue and spray.

As best I know (which is not to say I know much beyond some basics) fungi are really just a lot of little threads known as hyphae. Mushrooms and the like are just the fruiting bodies that release spores (there are types, such a verticillium that don't make fruiting bodies or spores and have other means of reproduction). The hyphae are generally inside the tissues of the plant/tree/leaf and, hence, won't be affected by any spray. Sprays only kill the spores that are laying around on the surfaces. It also should be noted that any one particular fungicide is only effective against certain fungi (check the label). There is some evidence that systemic fungicides can 'undo' certain fungal infections. Nevertheless, systemics are generally most effective prophylactically (the ultimate nuclear option).

IOW, for all practical intents, once infected, the hyphae are permanently in those tissues. The only cure is to remove the infected tissue - it is just a source of spores for renewing/spreading the infection.
 

amatbrewer

Shohin
Messages
310
Reaction score
387
Location
Yakima Wa
USDA Zone
6b
IOW, for all practical intents, once infected, the hyphae are permanently in those tissues. The only cure is to remove the infected tissue - it is just a source of spores for renewing/spreading the infection.

This may come from my ignorance and reading too much into something (“a little knowledge can be a dangerous thing”) but I can’t help but see a possible parallel, and wonder if there is a similarity, between fungal and viral infections.
For fungal infections, we remove and/or treat the material with the visible symptoms and spoors, but that is only to reduce the spread (to other plants, but to other parts of the same as well?) and stop the symptoms but does not to 'cure' the infection.
For the most part, for viral infections we treat the symptoms in an effort to help keep the organism healthy enough that its own immune system can rid itself of the virus, or at least suppress it enough that it can not spread and/or cause symptoms. (over simplified yes, but I think the general concept is correct)

So the question is; if an otherwise healthy plant, given proper care, is able to rid itself of the fungal infection, or it is really; once infected always infected?
 

0soyoung

Imperial Masterpiece
Messages
6,797
Reaction score
11,156
Location
Anacortes, WA (AHS heat zone 1)
USDA Zone
8b
So the question is; if an otherwise healthy plant, given proper care, is able to rid itself of the fungal infection, or it is really; once infected always infected?
I would say it as, given proper care, an otherwise healthy plant is able to resist infection. Plants/trees don't have immune systems like we do.

Living cells in the xylem (parenchyma) along rings and rays produce compounds that tend to be resistant to fungi and insect invaders. So, even though the fungus remains it remains in a container within the tree and will not have any further effect unless it can break through the container walls. Unable to break through the compartment walls, the fungus may then die unless it is one that digests cellulose (e.g., core rot).

I dunno if any of this applies to viruses or bacteria. Pseudomonas syringae, though, is not necessarily fatal to trees, but I have no knowledge of whether this is because of compartmentalization or that the bacterium is chemically done in in some fashion by the tree.
 

mdsai

Seedling
Messages
6
Reaction score
1
Location
St Louis, Mo
USDA Zone
6b
Well, learning more than expected; thanks to all - and this seedling experience.
Agree, that fungus is in the environment always, once in plant tissue difficult/impossible to fully eradicate; live with good practice/prevention; dispose of tissues/trees/soils badly infected.
Thanks all - quite interesting. I read an article on Sugar Maple die-backs and seedling effect and Anthracnose - interesting that the nearest maple to my site within 20 feet is a healthy Sugar Maple.
 

Attachments

  • Sugar Maple Antracnose.pdf
    1.6 MB · Views: 3

amatbrewer

Shohin
Messages
310
Reaction score
387
Location
Yakima Wa
USDA Zone
6b
Plants/trees don't have immune systems like we do.

Thanks, learned something new today! So I WAS reading more into it then was there. (as the saying goes "Correlation does not imply causation")
 

Leo in N E Illinois

Imperial Masterpiece
Messages
9,047
Reaction score
17,029
Location
on the IL-WI border, a mile from ''da Lake''
USDA Zone
5b
@0soyoung
I have to respectfully disagree with you about fungus. Fungus infections are NOT permanent in all cases. In fact a large percentage are transitory. They come, they go. It is fungal species dependent, so without a proper identification of just which fungus we are dealing with, It is difficult to say anything with certainty.

Plants do not have an immune system in the sense of a mammalian immune system, but they do respond to infections and can indeed fight off infections by mechanisms completely different than a mammalian immune system. Plants can exude certain carbohydrates, plants can alter their internal pH, plants can wall off infected areas with cellulose, they can encourage other non-pathogenic species of fungi to colonize their tissues in order for the non-pathogenic fungi to out compete the pathogenic fungi. Similar with encouraging beneficial bacteria to attack the pathogenic fungi. The whole system is not very well documented, but the ''body of knowledge'' is being developed.

The Blights, such as Chestnut blight, and Dutch elm disease are 2 fungal infections that indeed are pretty much permanent, once infected it is difficult or impossible to eradicate them. But these are the extreme cases.

Other fungi are ubiquitous in the environment. The ''Black Tar Spot'' of maples, only infects the leaves. When the leaves fall in autumn, the tree is essentially free of tar spot. But the tar spot lives in the soil over winter, spores are blown into the leaves of the trees in late spring, or early summer, and the trees become infected again. Only way to break the cycle is to move the tree to an area where the soil is not infected.

Systemic fungicides such as Cleary's 3336 and Daconil will clear the tissues of the trees of the fungi they target. They will not repair old damage, but there will be no new damage once the fungicide has done its job. This is why they are the go to fungicides for pine needle cast fungi.

Those points above are my areas of disagreement. I won't belabor the points, I don't have the time to dig up references.

This portion is mostly to the OP, @mdsai

More often than not, when I see fungal infections they are secondary, to an insect pest attack. Insects such as sucking insects like aphids or mealy bugs bite and leave wounds on the undersides of the leaf, then opportunistically a minor pathogen fungus gets in these open wounds and spreads a small zone of brown or black rot. Often if you clear up the insect pest, the fungus will not progress. I do like the idea of removing all the damaged leaves. With maples, this time of year, even small seedlings, a partial or even complete defoliation will not kill the tree. A new set of leaves will develop and they should be clean if you got rid of the insect. Always dispose of diseased leaves in a plastic bag and have it hauled away. Don't just drop them on the ground where they can serve as a source to inoculate the next round of leaves.

Pathogenic fungal infections can largely be avoided by altering the environment around the tree. If a tree seems to be picking up a fungal infection try moving the tree to a position with better air flow and more light. Trees on the ground should be put up on a bench or shelf. Don't crowd trees together, make sure there is enough space for a breeze to get through. Sun is excellent at discouraging fungi. Morning sun and late evening sun for otherwise shade loving plants is helpful. Full sun plants will more easily fall prey to fungi if grown with too much shade.

Hope these thoughts help. I would check and spray your little maple for insects first, then worry about fungus later, as I strongly suspect your problem started with insects on the underside of your leaves.
 
Messages
206
Reaction score
238
Location
California
USDA Zone
9A
@0soyoung
I have to respectfully disagree with you about fungus. Fungus infections are NOT permanent in all cases. In fact a large percentage are transitory. They come, they go. It is fungal species dependent, so without a proper identification of just which fungus we are dealing with, It is difficult to say anything with certainty.

Plants do not have an immune system in the sense of a mammalian immune system, but they do respond to infections and can indeed fight off infections by mechanisms completely different than a mammalian immune system. Plants can exude certain carbohydrates, plants can alter their internal pH, plants can wall off infected areas with cellulose, they can encourage other non-pathogenic species of fungi to colonize their tissues in order for the non-pathogenic fungi to out compete the pathogenic fungi. Similar with encouraging beneficial bacteria to attack the pathogenic fungi. The whole system is not very well documented, but the ''body of knowledge'' is being developed.

The Blights, such as Chestnut blight, and Dutch elm disease are 2 fungal infections that indeed are pretty much permanent, once infected it is difficult or impossible to eradicate them. But these are the extreme cases.

Other fungi are ubiquitous in the environment. The ''Black Tar Spot'' of maples, only infects the leaves. When the leaves fall in autumn, the tree is essentially free of tar spot. But the tar spot lives in the soil over winter, spores are blown into the leaves of the trees in late spring, or early summer, and the trees become infected again. Only way to break the cycle is to move the tree to an area where the soil is not infected.

Systemic fungicides such as Cleary's 3336 and Daconil will clear the tissues of the trees of the fungi they target. They will not repair old damage, but there will be no new damage once the fungicide has done its job. This is why they are the go to fungicides for pine needle cast fungi.

Those points above are my areas of disagreement. I won't belabor the points, I don't have the time to dig up references.

This portion is mostly to the OP, @mdsai

More often than not, when I see fungal infections they are secondary, to an insect pest attack. Insects such as sucking insects like aphids or mealy bugs bite and leave wounds on the undersides of the leaf, then opportunistically a minor pathogen fungus gets in these open wounds and spreads a small zone of brown or black rot. Often if you clear up the insect pest, the fungus will not progress. I do like the idea of removing all the damaged leaves. With maples, this time of year, even small seedlings, a partial or even complete defoliation will not kill the tree. A new set of leaves will develop and they should be clean if you got rid of the insect. Always dispose of diseased leaves in a plastic bag and have it hauled away. Don't just drop them on the ground where they can serve as a source to inoculate the next round of leaves.

Pathogenic fungal infections can largely be avoided by altering the environment around the tree. If a tree seems to be picking up a fungal infection try moving the tree to a position with better air flow and more light. Trees on the ground should be put up on a bench or shelf. Don't crowd trees together, make sure there is enough space for a breeze to get through. Sun is excellent at discouraging fungi. Morning sun and late evening sun for otherwise shade loving plants is helpful. Full sun plants will more easily fall prey to fungi if grown with too much shade.

Hope these thoughts help. I would check and spray your little maple for insects first, then worry about fungus later, as I strongly suspect your problem started with insects on the underside of your leaves.

I found this post while searching for ways to deal with a Japanese maple fungal infection that has spread through a number of my young trees. This was very helpful but I have one question for you @Leo in N E Illinois.

When defoliating for removal of infected leaves, is it better to remove individual leaves as in normal defoliation, or in more severe cases would complete branch removal be indicated?

I have a few 2-3 year old trees that I would basically need to remove all of the foliage to removed the infection. Thus, I’m at the decision juncture of defoliating completely or basically trunk chopping. Neither option is desirable.

I guess another question would be, can you leave some mildly infected leaves on the plant?
 

Leo in N E Illinois

Imperial Masterpiece
Messages
9,047
Reaction score
17,029
Location
on the IL-WI border, a mile from ''da Lake''
USDA Zone
5b
If the pathogen only expresses itself in the leaves, and seems to be confined to the leaves, like black tar spot, then a complete defoliation is the way to go. I would not prune off branches as an alternative to removing leaves.

If the pathogen seems to be more systemic, that it spreads through the branches and twigs. Then I would reach for one of the chemical fungicides. Daconil and Cleary's 3336 are broad spectrum, and have a low rate of resistance development. But it is very helpful to get an actual name for your disease. Then you can use a fungicide specifically labeled for the fungi in question.

Pruning off branches to remove a disease is a bad option, only if nothing else works.

You have a photo of your infection? I am not great at photo diagnosis, but I can try.

Another good resource is your local agricultural extension agent. They will be familiar with disease common in your local county, and will know which cures are allowed in your county. Every county in USA has at least one Ag Extension agent, usually a whole office full. They will also have knowledge of local plant disease specialists that you could take a sample to.
 
Messages
206
Reaction score
238
Location
California
USDA Zone
9A
Thank you. I understand: leaves only, no branches. And every last infected leave should be removed?

I’ve been treating with daconil to this point. And actually I treated prophylactically before leaves appeared. I’m already 1+ month into spring growth and the first flush is complete. No branches appear infected.

I’ve also got Bioadvance 3 in 1 on hand.

Thank you for the help.
 

Attachments

  • 10116520-C9BE-433F-8012-8645C523D8D2.jpeg
    10116520-C9BE-433F-8012-8645C523D8D2.jpeg
    173.6 KB · Views: 34
Messages
206
Reaction score
238
Location
California
USDA Zone
9A
...I think I should clarify one of my questions:

Because dry conditions are expected, can I leave mildly affected leaves on the tree during defoliation?

Or will leaving them on the plant spread the fungus no matter the environmental conditions?
 

Leo in N E Illinois

Imperial Masterpiece
Messages
9,047
Reaction score
17,029
Location
on the IL-WI border, a mile from ''da Lake''
USDA Zone
5b
If it is a fungus, you need to remove 100% of the affected leaves to prevent reinfection.

Honestly I can not tell what the cause is from your photo, not because of the photo quality, just because I am not knowledgeable enough. Maybe someone else can chime in? @Brian Van Fleet ? @markyscott ? @Dav4 ?
 
Messages
206
Reaction score
238
Location
California
USDA Zone
9A
If it is a fungus, you need to remove 100% of the affected leaves to prevent reinfection.

Honestly I can not tell what the cause is from your photo, not because of the photo quality, just because I am not knowledgeable enough. Maybe someone else can chime in? @Brian Van Fleet ? @markyscott ? @Dav4 ?

Sounds good. Thanks.

As of right now I’ve defoliated 100% of the plants that had it the worst. The others I’ve partially defoliated, healthy leaves and a few leaves with slight brown tips remain

I should add that we had an early season warm spell that woke them all up, followed by an extended period of rain and sustained moisture. They didn’t have great sun exposure during that time so everything stayed wet longer than it should have. Unfortunately the environment was right for pathogens to enter.
 

Similar threads

Top Bottom