Chinese Elm Bonsai losing leaves!

[bkonbay]

I bought a Chinese Elm Bonsai while vacationing in Florida. It is about 16 inches tall and the trunk is about 1 1/2" wide. It was used to being outdoors, but after I bought it, I brought it back to the apartment I was renting and have kept it indoors for the last two weeks. After bringing it home, I pruned it because it had long growth all over it. I also sprayed it with "Garden Safe" fungicide 3 by Schultz. It is a Neem Oil spray. It has been living inside for the last two weeks with the air conditioning on, instead of living outdoors. I live in Michigan and will be taking it there next week and will be keeping it indoors all of the time.

My problem is that this Bonsai is dropping leaves constantly. The leaves are turning yellow and when I touch them, they drop off. They are not curled up or dry and crusty, they just turn yellow and drop off. There is also a lot of new growth on the tree, but even some of the new little leaves turn yellow within a couple of days and fall off. At first I thought it was in shock because of the change in temperature, pruning, and fungicide spray. But for two weeks now, it is really dropping leaves like crazy and I am beginning to get worried. When the yellow leaves fall off, they are either all yellow or have just a few green spots on them. In another week I have to put it in the car and transport it to Michigan where I live. I have successfully owned two other bonsai's for three years -- one Ficus and one Scheffelera (sp?).

Can you tell me what I might be able to do to stop the leaves from falling off my new Chinese Elm. I am losing about 15-20 leaves a day, and I'm afraid if it doesn't stop, my tree will die.

Thanks,
Kathren

[The Helpful Gardener]

I am always a little hesitant giving advice on a tree that was raised tropical but moving to temperate zones, especially one like Ulmus parviflora that would be happiest raised as a temperate tree.

If you read through the bonsai articles on the site (I recommend doing so as it will provide more insight than a quick missive like this one) you would see I am no fan of keeping ANY tree indoors year round; they really do need some time outdoors to stay healthy. Moving indoors from 80 degrees and 80 percent humidity to 68 degrees and 40 percent humidity is going to cause even the healthiest tree to rebel; this is exacerbated by light conditions changing considerably (even clear glass only lets through about 80% of wavelength). If you didn't see considerable leaf drop through this process I'd have been amazed...

Elms can be touchy, and if you don't have previous bonsai experience this is going to be a really tricky move. Luckily spring is coming and that works in your favor. I'd try to keep it watered and in as much indirect light as you can find. Keep the humidity higher by misting; a humidity tray wouldn't hurt either. Leaf drop should be followed by new buds; keep an eye out for sooty mildew (often a problem with these trees) and treat it IF it shows up (I'm not a fan of constant spraying and regular neem oil treatments won't allow leaves to breathe; may be part of the issue). When you get the tree back north, I'd keep it outside on nice days and bring it in when it is going below 40. Eventually it will acclimate; this plant is Zone 4 hardy, despite it's tropical upbringing. As for keeping it indoors all the time, DON'T. A balcony, window ledge, porch or some similar arrangement is best for the growing season, with indoors as a last resort (I'd let it take a few 30 degree nights before I brought it in; even a fake winter is better than none at all). Getting it back out as soon as you get forty degree days will also help with the dormancy; a cool room or protected porch is better as it would allow a full dormancy. Read the articles and if you still have questions we'll talk...

Scott

[bkonbay]

Dear Scott,
Thank you for all of your advice on taking care of my Chinese Elm Bonsi in the Upper Peninsula of Michigan. I have been following your helpful hints and advice since I returned to Michigan a month ago.
“Elmerâ€

[The Helpful Gardener]

A little of this is just the nature of U. parviflora but I suspect the other issue is photoperiod (amount of light. At the latitude in Florida, the sun's rays come directly through the atmosphere straight down. Up in Michigan, the curvature of the planet means the rays are coming through the atmosphere on a diagonal. Look at a 2 x 4 you cut on a 45 degree angle. The depth of the board is two inches until you measure the width of that cut face and it's more like three. SO...using that model to think of the light coming through our atmosphere, it's got 50% more atmosphere to go through with the asttendant loss of UV, infrared, etc. SO even if you have it in the same facing, same period of light, etc., it will get 50% less light. A big change for a little tree...

The discoloration worries me a little, but you have treated with neem oil, so fungal doesn't seem likely. Was it in full sun right after you sprayed? Oil based sprays need shade for a few days after or the oil intensifies any sun to the point of burning...

Get it back outside as soon as possible, even if just for the day and in at night, and I think it'll be fine. All the new growth is a sign of good care, so I think it's in good hands...

Scott

[bkonbay]

Thanks again Scott for your encouragement and your wisdom. Your explanation regarding Michigan sunlight was very interesting. Hopefully,
"Elmer" (I named my Chinese Elm Tree) will adjust to this lack of sunlight!

As I said, he seems to be holding his own. He has new buds popping out wherever leaves have fallen off. I am giving him as much fresh air as possible.

I did apply neem oil spray the second day after I purchased him because another Bonsai that I had bought had leaf spot -- so I sprayed them both.
However that was a month ago. I guess my only question that I have right now is -- If the brown spots on the leaves and edges of the leaves continue, should I go ahead and spray him with neem oil once again in case he has a fungus? I am not sure I would recognize what a fungus looks like -- and I can't decide whether spraying him would put more stress on him when he's already stressed, or whether it would save him from dying of a disease! He seems to be pretty strong, but just continues to lose lots of brown spotted leaves. Would sending you a picture help? Elmer and I thank you for your help and your patience!

Kathren

[The Helpful Gardener]

Hi Kathryn,

Yes, with the constant change of leaves the oil would be long gone and another spray would'nt be a bad idea; just remember the caveat about sunlight and oil...

Scott