JM leaves look unhealthy. What have I done?

[cornfed]

 

[Colorado]

Too much sun/compromised roots.

Someone will suggest fungal, but I dealt with this for two years until I started growing my JM in mostly shade. Now I don’t deal with it and they grow great. I do not think it is fungal.

 

[RKatzin]

What type or cultivar is this, what's it growing in and what are you feeding it? I see some nibbles and chlorosis if it's a green leaf variety.

 

[PA_Penjing]

This happens to my landscape and grow out maples every year. I push them hard with fertilizer and I think the new tender growth just gets smoked by the sun and heat come this time of year. I agree with colorado. My solution was to shade the few maples I had in pots, because those weren't being grown out they didn't have the tender new growth to worry about in July and august anyway, for the most part

 

[RKatzin]

Okay, counterpoint. I have dozens of Japanese Maples. The weakest, is least tolerant, get full sun until at least high noon. The stronger, including Tridents, Shishigashira, Hupps Dwarf, Mikawa yatsubusa, Atropurpurium will be in the sun till about three and the queen of the sun Glowing Embers is full sun till about six in the evening. They're all in pumice and I feed a low nitrogen fertilizer, 676, slow release cakes and I'm watering twice a day in the heat.
I think it is a matter of medium and fertilizer. I lost a tree recently. A four year old cutting that I hadn't transitioned into pumice yet and was still in a potting soil mix. Fine one day and totally dessicated the next after a heavy thunderstorm. Usually in a case as this I just set it back and let it recuperate, but this one was over the line and never came out of it.

 

[cornfed]

Thank you for the responses. I have a little more detail. Forgive me for not putting any of this in my original post.

• It is a Kashima JM.
• It was a 2020 cutting I bought from somebody in the NBS.
• I haven't done any rootwork, pruning or wiring. I have just been letting it grow.
• It gets full sun from sunrise until about noon, then it is in the shade for the rest of the day.
• It's been reaching 80s & sometimes 90s around here the past couple weeks.
• I water it once a day (twice a day when the temps are 90+).
• It shares a bench with a bunch of other trees and none of them have leaf issues like this.
• It had frost damage in April when I left it outside one night and the temp dropped to the mid 20s.
• It's in a super well-draining mix of pumice, turface, DE & sifted pine bark.
• It's in an air-pruning pot. Lots of holes.
• I have been hitting it with liquid fertilizer weekly for the past two months. I started with a 10-10-10 and now do 20-20-20.

What it looked like 3/20/2021​

 

[PA_Penjing]

You mentioned that it sits on a bench with other trees but are they JM? If they are JM, are they different varieties or just green? Different genus have different tolerance to sun as do different species and cultivars. If that weren't enough, the substrate, size and shape of the pot will change things too. Just because the sun is damaging one tree doesn't mean it would damage others. It's possible that it is something other than the sun but I'm pretty sure that is your most obvious culprit. especially given the time of year.

 

[PA_Penjing]

This year my prebonsai JM grew trouble free, as it usually does because I protect it. My landscape maple grew like gang busters until this past heat wave fried the growth tips. That tree happens to grow in a shaded-ish site but the new grow extended over a fence into full sun territory. I have some trident maple growing out on the south side of my fence currently. They are known to be more sun tolerant but they are getting absolutely blasted right now (it's 97 F today). And they are starting to show that deformed growth just like the photos you posted. This doesn't prove anything I'm just letting you know I have some experience with this over the summers. Oh and the 50 odd prebonsai maples at the nursery WILL suffer from this same kind of damage in the next couple weeks as the shade from the oaks begins to expose them to more sun. Don't sweat it. I usually just cut off the crispy stuff when the heat breaks a little and no rain is forecasted. they'll respond with new growth if the roots are nice and cool

 

[Firstflush]

In my opinion those NPK numbers are quite high, others may have a different take. Personally, I would dilute down to around 5-5-5 or less, which is plenty at the rates you fertilize. You make have salts building up in the substrate.

 

[penumbra]

In my opinion those NPK numbers are quite high, others may have a different take. Personally, I would dilute down to around 5-5-5 or less, which is plenty at the rates you fertilize. You make have salts building up in the substrate.

I agree, I think its time to back of on the heavy feeding for duration of mid summer.

 

[Wulfskaar]

The fertilizer I've been using (Uncle Bill's Bonsai Brew) is 3-3-3 and is done once every two weeks. 20-20-20 every week seems crazy high to me based on the instructions for the stuff I have.

My recent research on browning of leaf tips (just like yours) leads me to guess that you are either over-fertilizing or the watering isn't quite right.

 

[cornfed]

I have maybe a dozen different (mostly deciduous) species and none of the others are JM (First year, trying to figure out what I like).

And I am committing the sin of treating them all the same. Water at the same time. Fertilize the same. Substrate about the same. Only difference is I also have a "Sun Bench" which is full sun from about 9am-3pm.

I got to 20-20-20 after fertilizing for several weeks with lower NPK products without really seeing any results. Since the drainage is so good I suspected that I was washing all of the fertilizer out the subsequent day of watering.

Since all my trees are in the growth/development phase, I figured high NPK fertilizer would help push growth and thicken the trunk. I just want them to regrow the roots I cut off in the Spring and thicken up as much as possible.

My substrate/fertilizing/watering philosophy comes from Walter Pall's blog. I was just a little nervous to triple the dose like he does so I slowly ramped it up until I started to see results. I was also planning to fertilize the same way through to October, but now I have doubts because I respect your opinions.

I will move this particular tree to a full-shade spot and see how it responds.

I want to trim off all the leaves I don't like as well, unless somebody thinks that is a horrible idea.

 

[cornfed]

I bought Bonsai Heresy a couple weeks ago and was a little disappointed when he stipulated near the beginning that all of his research was for more mature, refined trees and that development trees often have drastically different needs.

Critically, the comments in this book are--except for one or two chapters--about mistaken notions in the care and management of older, refined bonsai, not young whips in pots. the techniques used for each are worlds apart, an epic difference. young plants on the road to being future bonsai are treated nearly opposite to mature bonsai in when to prune, how to fertilize, what soil media to use--practically a complete reverse. And young trees, although you may find a few useful tidbits, are not this books' subject.

Michael Hagedorn, Bonsai Heresy, pg 5.

Somebody needs to write THAT book, too!

I almost think it would be nice to have a "Development/Growth/Thickening phase" sub-forum here on BNut.

 

[RKatzin]

My substrate is much the same and I found it really difficult to use liquid fertilizer. I've switched to a slow release cakes and granular fertilizer and I'm seeing significant improvement in the second year. First year everything did show increased growth, but this year's growth has been robust across the board for the git go. I highly recommend the sumo cakes from Sumo Bonsai. My trees say, 'Delicious'!

 

[PA_Penjing]

. Since the drainage is so good I suspected that I was washing all of the fertilizer out the subsequent day of watering.

This makes a huge difference, there is a school of students who grow trees in purely inorganic soils and feed very heavily, since it gets washed out with every watering. I can't remember who it was that wrote the articles I read about it but I believe at least one member here uses or used to use this practice. I believe it was M. Frary... who was mixing up double strength miracle grow for his stuff. The substrate matters big time.
The first couple years I grew trees I treated them all the same, it's actually not a horrible way to get a baseline understanding of what it takes to keep everything happy. IMO of course. I couldn't just "know" how to water everything correctly without some kind of baseline. I did waterlog some pines along the way but that's called experience and it's a good thing if you learn from it

 

[Leo in N E Illinois]

I bought Bonsai Heresy a couple weeks ago and was a little disappointed when he stipulated near the beginning that all of his research was for more mature, refined trees and that development trees often have drastically different needs.



Somebody needs to write THAT book, too!

I almost think it would be nice to have a "Development/Growth/Thickening phase" sub-forum here on BNut.

This Forum already has 43 or 44 sub-forums. Almost nobody bothers to scroll down past the top 15 forums. In reality the entire "Bonsai Nut" forum is a "Development/Growth/Thickening" phase forum, as relatively few of us have trees in top exhibition stage. Not trying to be harsh. Its just that there are already too many sub-forums, in my opinion.

Your leaves could be the product of a "single event", let it get too dry, just once between watering and that sort of deformation can happen. Too much sun, and heat can do it also. The good news, cut the deformed leaves off, if weather cooperates the replacement leaves will be fine.

This summer will be a problem. The heat in the PNW will eventually travel our way, move this tree to the shade when temps are over 90F.

 

[cornfed]

34 days ago I put this plant in a spot where it gets dappled to full shade most all day. I also fertilized with some fish emulsion. It was the first time I used that product, so I was unprepared for the smell. My beagle was absolutely intrigued by it, though.

Within a day my wife found the tree bare rooted on the ground after a beagle attack while I was working. She did her best to get the tree back in the pot, and I finished the job when I got home. I watered it well and stashed it in a little plastic greenhouse that sits in the shade against the fence.

Anyways, this is that tree today. You guys were right, it was the warm breeze and heat that was doing her in. She looks much more healthy now. She even survived the beagle attack. Thanks guys!

​

 

[Vali]

My substrate/fertilizing/watering philosophy comes from Walter Pall's blog.

Be aware that not long ago, on this site, he stated he doesn't fertilize like that anymore

 

[cornfed]

Be aware that not long ago, on this site, he stated he doesn't fertilize like that anymore

My trees are all in the growth phase, I'm happy so far with the heavy fert. But thanks for the info. When they move to bonsai pots I'm sure I will change the regimen.

 

[augustine]

Hi, I have the same thing frequently on my J. Maples. The leaves just get beat up. I don't know why but they remain vigorous to this day. (They are in morning sun about 4 hours and dappled shade the rest of the day.)

The root maker pots, with all the holes, may be drying out too fast?