Curling Palmatum leaves...Why?

JD_Wolfe

Hello people that know more than me,

I'm pretty new to bonsai and newer still to Japanese Maple bonsai. I live in Zone 3b (Calgary, AB, Canada) -- it's cold and windy and we experience temperature inversions regularly.

Calgary: where Japanese Maples go to die.



What I have is what I estimate to be a five-year-old palmatum pre-bonsai. When I purchased the tree it was already looking a little less than great. I asked the owner what his thoughts were on the curled and crispy appearance of some of the leaves. He advised me that the tree had been under heavy shade cover for a number of weeks and probably needed some light. I found this answer somewhat suspect considering what I've read of palmatum’s preference for dappled shade and the fact that it was rather (to my eyes anyway) bright in the greenhouse. Nevertheless, I took its somewhat weakened appearance as an opportunity to negotiate a fairer price and I left tree in hand altogether pleased, optimistic that I could rehab it well enough until dormancy.



Well...that hasn't worked out quite as well as I hoped.



The tree hasn't declined particularly: some of the young shoots are gaining strength and the tree has a sufficient supply of healthy, well shaped (albeit large) leaves -- but it's not thriving. In addition to the growth there has been a slow, steady development of misshapen leaves that brown along the edge, curl upwards, and curl laterally to the left and right. I've checked out the roots and included some pictures below; they (the roots) don't look great, but not all that poor either. Though it may be hard to tell from these lousy cell-phone pictures -- my camera's busted -- I'd appreciate a second opinion.



Because I obtained this tree late in the season I haven't attempted repotting it into my usual mix of river sand, turkey grit, horticultural charcoal, decomposed fir bark and fluorite. The previous caretaker told me he had successfully overwintered the tree in it's present mix but that it took a very long time to push buds (mid-June. Which is late, even for Calgary). The soil is very dark. I think it's mostly decomposed bark and perhaps, leaf mold (?) that has broken down a lot; I saw a few bits of peat on the surface that I removed -- smells wet and loamy. The soil texture is quite firm but spongy enough that it appears to drain ok -- really doesn't look far off from what Peter Adams recommends (more grit would be nice). I figured it wasn't worth risking a repot especially if it had already made it through one winter.



Care that I've provided:


Since I was advised that the tree was light deprived, and the weather was already starting to get pretty cold (we had already had several considerable frosts) I decided to keep the tree indoors four feet from a screened window under a 60 watt blue halogen. Calgary gets WINDY like you wouldn't believe and the idea was to gently acclimate the tree to the cooler weather by letting the cool air drift in waft over the leaves. I kept a very close eye on it to make sure that the leaves weren't desiccating. On average it drops between 0-3 C (33-37.5F) at night but soil temperature tends to stay about 8-9 C warmer (48-54F). My guess is it needs to get colder before I'll see anything in terms of colour change and leaf drop (and it will, to be sure).

I water the tree when the surface is just beyond being damp to the touch (if you dig in with your finger it's still slightly damp). I tried the chop-stick method which I've got down to a science with my Chinese elm and Euonymus, but I was worried that I couldn't estimate the dampness of the stick quite right with the maple. I water with tap water that I sit out for 24 hours and then amend with aquarium conditioner to down the pH (the majority of Calgary's water is from a limestone reservoir - average pH is 8.2). I water by the method Gustafson suggests: once misted to break surface tension, then again to saturate 10-15 minutes later with a light upward facing rose, and finally a cleansing rinse 15-20 minutes after that.

I have not fed this tree since I obtained it in early September.

The former owner fed it bi-monthly with "Chrysal Liquid Bonsai Food (4-6-6, with trace elements)"


At any rate, the tree began to show signs of improved vigor, but also persistent issues with the leaf shape that seem to be getting worse.


Potential culprits:

I found a caterpillar and a spider beneath one of the leaves. I named them Herman and Judith because I believe it’s immoral to dissociate myself from corporal punishment. Some of the damage is definitely caterpillar-related, but the curling I don't understand. I applied a light spray of Neem oil mixed with water and dish soap to take care of any other potential pests a few days ago.

RIP Herman, Judith and your kin.


The nursery I got the palmatum from had a bad infestation of spider mites in early August. I didn't see any spider mites on my tree or evidence thereof (and I checked in on this tree over several months before I bought it), but I wonder if a haphazard pesticide applicator may have damaged the leaves? I know 2-4D can do a number on leaves but I can't imagine what purpose they would have for spraying herbicide in their tropical section. Any idea if there is a pesticide used for mites that might be responsible for this sort of damage?



I'm tapped...Please help me.



How do I make this better?



Love and respect for anyone with the patience to meander through my parentheses.



Sincerely,


J.D. Wolfe


P.S. also attached are some blurry pictures of the leaves to give you an idea of the damage.

Attached Images

	Blurry Palmatum 1.jpg (66.9 KB, 34 views)
	Blurry Palmatum 2.jpg (64.5 KB, 20 views)
	Blurry Palmatum 3.jpg (72.5 KB, 35 views)
	Blurry Roots 2.jpg (72.2 KB, 40 views)
	Blurry Palmatum 4.jpg (69.9 KB, 46 views)
	Blurry Roots 1.jpg (69.4 KB, 38 views)

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tachigi

J.D., A couple of observations from your post. The first would be

while Japanese Maples are very cold hardy they can't handle the drying effects of the wind. The leaves will curl and if you don't intervene with a mist they will eventually fall off.

The second is that the picture you show of the tree unpotted definitely giving me the impression that your tree is root bound. Which would be a contributor to a tree in a declining state.

At this point I would suggest that you take a chop stick and try and loosen the root ball a little by wiggling a round gently and give it a good feeding of 0-10-10. My guess is that in your area that the leaves will drop soon and the tree will go into dormancy. Protect it well this winter and in spring do a repot and see where that will take you.

Good Luck

__________________
Tom

Shady Side Bonsai
Bonsai Vault
4MAAT

JD_Wolfe

Tachigi,



Thank you so much for taking time to respond. I have been misting the tree twice daily, and the tree is seated above a humidity tray, however, I have taken care as of late to provide better shielding from the wind and hopefully this will help. The angle of root pictures I think is slightly deceiving as both pictures are taken from the same side of the plant where the collar is most prevalent. I do agree that the tree is getting more pot-bound than optimal and I will be repotting in the spring. I haven't fed the tree simply because I thought it was a bit late in the season, but if you don't think it will hurt I will try loosening the root ball and do so.

Thanks again.

Best,

J.D. Wolfe

Bonsai Barry

I'm wondering if you might be overwatering.

__________________
Bonsai Barry

"Our talent lies in our choices."

JD_Wolfe

Well, there is possibility of that. I've been watering about once every three to four days (not on a schedule, just as I think the tree needs it), but due the light draft exposure I have been misting the tree at least once a day (usually twice). Perhaps the frequent evaporation of the mist on the leaves is part of the problem. I did notice when I removed the root ball from it's pot that quite a lot of water was released (about 1/3 of a cup) which tells me it's not draining right -- mind you, at the time that I looked at the roots I had just watered five hours prior (still too much retention if you ask me).

Thanks for your response Barry

Regards,

J.D. Wolfe

ALDEVAUX

The symptoms shown on your pics certainly do not look like herbicide damage which would affect, not only a few leaves, but all of them.
The caterpillars did chew part of the leaves and the curling could be due to some of the leaf veins that were damaged by the same caterpillars or another insect.
However, since Japanese maples are not winter hardy in zones 5 and below, the tree should not spend the winter outside even if you try to protect it with a very good mulch. The only way for you to overwinter it, is to keep it in a cold room, or greenhouse, at not more than 40 F until spring.
Furthermore, this tree should not be kept in your house for any length of time. At this time of the year, I suggest that you leave it outside in a well protected place until the leaves fall, because it is resistant to the early frosts which, in fact, are good for its dormancy.
In spring, you should repot the tree in a very well drained bonsai soil which should be watered often to prevent underwatering because root rot is caused only from soils which retain the same water for too long a time around the feeder roots.
Good luck.

tachigi

BINGO......A third of a cup after 5 hours tells me that your soil is way wrong. Slip pot it in a slightly larger pot with some well draining mixture. This should help at least with some drainage issues till spring rolls around.

__________________
Tom

Shady Side Bonsai
Bonsai Vault
4MAAT

JD_Wolfe

Thank you Aldevaux and thanks again Tom. I will do all that has been recommended by you both. I knew it was going to be real challenge to grow palmatums in my environment and chose to try it with considerable trepidation, but here we are, so I'll do my very best to make it work.

I just wanted to clarify one or two things:

Tom: You've suggested that I take the root ball, as is, soil more or less intact and place the tree into a larger, fast draining pot with larger grained drainage grit lining the bottom and surrounding the existing roots and soil. Is that correct?

Do you still recommend teasing the roots apart slightly, and lightly fertilizing with 0-10-10 in light of this pseudo-re-potting?

Aldevaux: I live in an apartment with limited options for shelter and sun. Overwintering is the biggest challenge by far. To this end, I have built a lath cage which I plan to seal up in polythene and then port a hole at the top and bottom to run pvc tubing to my window. This is the Thermo-syphon idea discussed elsewhere on the forums. If this doesn't work, then it's going to my folks garage (which means I'll be visiting them a lot more often than usual...oh well...it's a free meal).

Thanks once again to everyone who has offered their assistance.


JD Wolfe

JD_Wolfe

Mr. Devaux,


I wish I had read your post on japanese maple hardiness earlier (http://forum.bonsaitalk.com/f7/impo...aple-10143.html)


It seems like there is a fine line between sound Winter care and over-babying palmatums. Did I misread your article, or did you say that some of your palmatums survived, and indeed, did better with less protection? Is this the motivation behind your advice to get the tree out of my apartment and into the cold?