Japanese Maple Disease Questions

6 years ago

(Zone 8) Hey, I recently got this japanese maple at a discount from a nursery because it was quite obviously in bad condition. All of its leaves were dried up, brown, and hanging. I did a fair amount of pruning and defoliated the whole tree as onlyabout 2 leaves had any green on them. Then I noticed these black spots on the trunk as well as a lot of black twigs. Could someone please help me identify the cause of this? I think I may have caught it early so maybe I can fix it. Thank you

Featured Answer

waynedanielson

6 years ago

You most definitely do fertlize stressed plants...just not drought stressed plants.

This is pne of those things folks hete preach like a mantra...there's a nugget of truth, common misperceptions, and faulty logic, mixed together, and out comes a well intentioned maxim, with supporting evidence that sounds good, and it's entirely not the right thing.

If it's pseodomonas, it may pull out. You did the right thing in pruning off, and time will tell. If it's another disease evidenced by dry, curled leaves that persist on the stem, crack the root ball. It there a smell like a sewer, or dead roots with an orange color under the bark (cortex), i don't have a good prognosis.

You have a sick plant. Give it some food. You don't go to the doctor and say, sorry doc, i can only take these meds when i'm healthy.

Ok, so bad logic in the first place don't excuse poor analogies in the second. But...sick plant, help it. Stressed plant, help it. Dry plant, the only help it needs is water...fertilizer when dry can make it worse.

Comments (16)

Toronado3800 Zone 6 St Louis
6 years ago
I dunno. Sanitize them pruning tools before taking them to another tree though so you don't spread whatever.
ken_adrian Adrian MI cold Z5
6 years ago
nearly the perfect example of loving it to death ...

you cut off the only food making machines it had .. leaves??

put it on the north side of the house.. and ignore it for 2 months ... but for an occasional sip of water ..

hope you got a major discount ...

ken
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gardengal48 (PNW Z8/9)
6 years ago
Black stem discoloration looks like bacterial blight, Psuedomonas syringae, an issue a number of JM's are extremely prone to. Depending on how far the infection has penetrated the tree, it may or may not be recoverable.
Mike Fin
Original Author
6 years ago
ken, all its leaves were dead and defoliating a Japanese maple is a common practice from what I understand.

garden gal, thank you for the input. would the infection likely only have penetrated where the black parts are. How would you go about helping it recover?
Mike Fin
Original Author
6 years ago
fungicide spray?
waynedanielson
6 years ago
if the leaves were curled, dried, and still on the stem, i'd crack open the root ball and see what may be there to find.

At this point, you're best bet is a little fertilizer (think miracle gro in half strength) and while you don't want to cut water off completely, make sure the problem isn't too much water.
gardengal48 (PNW Z8/9)
6 years ago
At this point, I'd just leave it alone. JM's can recover from psuedomonas, provided the infection is not pervasive throughout the tree. As it is a bacterial concern, there is little you can do to control it - generally pruning well below any signs of infection is pretty much the procedure to follow.

And I would NOT fertilize at this time. It is a very well established tenet that you NEVER fertilize stressed or ailing plants. They are unable to metabolize the fertilizer properly and it simply stresses them further. Also, provided you have used a fast draining potting mix, water as normal.

Japanese maples have a unique ability to releaf pretty routinely after some sort of stress or shock that causes leaf drop. Are there any viable looking buds present? I'd give it a few weeks to see if any buds form before throwing in the towel. If no sign of buds or any foliage development over the next month or so, then I wouldn't hold out strong hope of recovery.
Mike Fin
Original Author
6 years ago
thanks garden gal, much appreciated
gardengal48 (PNW Z8/9)
6 years ago
OMG - there is just so much wrong with the above!!

The first place to start is the concept that you need to "feed" plants. You don't - they are not children or pets - and fertilizer is NOT plant food. This is a popular misconception that promulgated by fertilizer manufacturers and misinformed gardeners like the above. Plants manufacture their own food through the process of photosynthesis. All a fertilizer does is supply nutrients the plant may need to effect photosynthesis IF the plant is unable to access them from the soil. Fertilizer is not a cure-all for ANY ailment......it is NOT plant "medicine" so forget the doctor/patient analogy, which is completely specious!

If the tree has no leaves, it cannot photosynthesize. If cannot photosynthesize, it cannot process any nutrients or other fertilizers that may be applied. They are either wasted unused or absorbed but unprocessed, creating additional stress. If you need to fertilize - and containerized plants will require fertilization as potting soil has minimal nutritive value - you need to wait until after the tree releafs.

Any qualified horticulturist or plant pathologist will tell you not to fertilize stressed or sick plants. They do not need it, can't process it and adding it unnecessarily is typically detrimental to any recovery. In fact, fertilizer should not be routinely applied in any case, unless a nutrient need/deficiency is known to exist. A diseased plant is not a need to fertilize..........a stressed plant is not a need to fertilize - unless it is the lack of necessary nutrients that is causing the stress.
waynedanielson
6 years ago
There is not a single topic where qualified horticultural professionals do not have dissenting opinions. Indeed, over time, yesterday's crackpot theory becomes today's widely accepted practice. Andvthe reverse is equally true. I can provide examples of each.

I have no problems with disagreement...it means we have views that are different, nothing more.

I can tell you this much...technically, no diagnosis should be given without a lab report. In practical terms, symptoms are given, probable diagnosis are given, no lab ever consulted. Same with nutrient issues. Very few are going to go through the trouble of collecting samples, sending them in, and waiting...and nearly every soil test i've ever seen has at least a token amount of fertilizer recommended. And who exactly is going going to go for a tissue analysis? Except in extraordinary circumstances? So making this claim is misleading, it's an attempt to shut down dissent, not create a conversation.

Let's not even start going down the rabbit hole of analyzing and interpreting soil test results...basically, that's one subject where there is no agreement.

I'll admit most people fertilize where they have no business doing so. I won't comment on some of the products out there or the claims made by various parties.

In particular instance...we have a plant recently acquired, still in a pot. Trying to exclude container practices while claiming the umbrella of established landscape plantings is misleading.

For the record, i'm not suggesting we fertilize this puppy till there is no fertilizer left on the county. I'm suggesting a half rate dose of a liquid soluble, aka, a shot in the arm. It can do little harm...and can have the benefit of pushing new growth. Explaing how photosynthesis occurs...great...now, how do plants take up nutrients?

There needs to be room for dissenting views, in many forums of life. I'm not promulgating crazy high doses, or mix your own concoctions because i took a high school chemistry class...this is not a radical proposal i'm making. And frankly, it's one respected horticultural professionals across the country give routinely.

Feel free to disagree...you can be a qualified and respected professional and disagree. Especially in horticulture.
Daniel Wooden
6 years ago
Can anyone tell me if this is normal for my Japanese

maples? The stems are changing color.
gardengal48 (PNW Z8/9)
6 years ago
I am not sure what you are referring to specifically. Can you explain further or provide photos that better illustrate the situation?

One item that is somewhat perplexing is the presence of a second 'stem' emerging from the potting soil. Are these seedling trees or grafted?
Daniel Wooden
6 years ago
last modified: 6 years ago

They were sent to me as saplings. The stems are changing color. I believe they were grafted however I am not sure. I imagine they are either seedlings or grafted one or the other. If you see in the picture they are turning from the green to the brown color.
ken_adrian Adrian MI cold Z5
6 years ago
you should have started your own post ... rather than bury this new topic in an old post ... next time anyway ...

'seedling' and 'grafted' are mutually exclusive words... one or the other.. but they cant be both ...

it is not uncommon in young trees ... for the trunk to change colors.. as the roots start coming out of dormancy ....

i wouldnt be surprised if that parts that are not changing.. are dead.. time will tell ... you could gently pull back the media.. and find out whats going on where the two parts are joined ... im wondering if they are planted too deep???

why are you growing them in what looks like straight perlite.. or is that grit???

welcome to the forums ... i do believe there is a JMaple forum .. but youre fine here ..

ken
Daniel Wooden
6 years ago
That on the top is gnat nix it keeps the fungus gnats from coming up out of the soil. It works like a charm. I bring the trees in in the winter and those pesky gnats go everywhere. Should i try and transplant them?