An important Physiological disease of japanese maple

ALDEVAUX

I live in USDA climatic zone 4 and the first japanese maple I acquired for bonsai was overwintered in a cold room of my basement where the temperature was 40 F minimum . It grew very well during the summer 2004 and was overwintered for the second winter in a cold greenhouse with 3 in thick sterofoam padding around the nebari and sterofoam pot and finally covered with a thermal cloth. My other native trees did not have the special nebari padding. In the spring the tree looked well with nice buds ready to open. In may, the buds never opened and the plant died. The root system was very well developped and healthy looking and was as large and as long as the trunc and branches. All my native trees remained very healthy up to date.

I took the tree to the plant pathology diagnostic laboratory where I worked part time for 30 years for confirmation of the disease by the pathologist in charge. The next day I was told that microscopic examination of the xylem vessels at different parts of the trunc showed collapsed cells that blocked the vessels and was definitely caused by what seemed a severe climatic temperature stress which is often observed on non-adapted trees of my climatic zone . No parasitic pathogens were later isolated from the tree.

I learnt my first lesson in fiding out that japanese maples are not hardy in zone 4.

So, for the benefit of bonsaists who want to grow trees in climatic zones in which there is lack of hardiness or lack of a dormant period , they should know that trees may suffer from a physiological disease which eventually causes death. Maybe it has already happened to people who have posted in the “dying bonsai” section of this forum without really knowing the real cause of death.

Non-adapted trees can suffer climatic stresses caused by very low temperatures during the winter or sudden drops of temperatures (sometimes more than 10 degrees celcius during a single day in zone 4) most often during late spring and early summer when the plants grow vigorously. It could also be a combination of both or even other factors like too much heat and dryness. They may not die after the first few stresses but if these factors re-occur often enough as the years go by, they will eventually die. I have personnally experienced many cases of these diseases during my 30 years career in my plant diagnostic laboratory for zone 4 only, and also with my first japanese maple as I explained earlier after it’s second winter where I had given it much more protection than my native maples.

This is a typical example of what can happen to a non-hardy tree as is the case of japanese maples that you may want to grow in USDA climatic zones 1,2,3 and 4, for where they lack hardiness and in zones 11 for a lack of a dormancy period.
Some of the published hardiness zones data for japanese maple give zones 5 to 9 as shown in these references:

http://hort.ifas.ufl.edu/trees/ACEPALE.pdf
http://www.cce.cornell.edu/programs...r/zonesumm.html
http://sis.agr.gc.ca/cansis/nsdb/cl...shrubs2000.html
http://wabcweather.abclocal.go.com/...day=1&region=NE
http://www.mountainmaples.com/WS4D_...d&Condition=is&[Class]StoreFrontID=3&Condition=and&Condition=contains&[Class]Alpha11=e&SortBy=[Class]Text1&RecordsPerPage=20&Database=Class&BreakTable=20&Page=1&LinkField=[Class]Text1&Results=results(comp).html&Results-1-Record=testproduct.html&Results-Table=results(comp).table&Table-Color-Even=

http://www.monbonsai.com/lesbonsais...og/cat_erab.htm
http://www.monbonsai.com/lesbonsais...og/cat_rust.htm



But, this does not mean that you cannot grow japanese maple in these zones but bonsaists must realise they need much more protection than native trees and have to be grown for at least part of the season in either a well equiped cold room in your basement, a controlled environment greenhouse or a controlled environment growth cabinet, all of which are very expensive to buy and to maintain. The bonsai nursery where I live grow them in complex greenhouse sections. They also have to be protected from other temperature stresses in the summer.

A forum member named jportock mentioned in another post, and I quote : “Then you should also consider that if you are able to mimic the conditions that any species lives in it doesn't matter what the actual climate is in your locale. Something that I have had drilled into my brain since I began reading this forum is that the care of various trees greatly depends on where you live. I have not heard anyone say that there is some species that will die in some geogrphic location no matter what conditions you keep it in.”
This is very true because with the technology we have developped today, you can grow a plant anywhere in the world, even on the moon. Most botanical gardens grow plants from all over the world in their greenhouses. In Montreal, Canada there is a place called the “Biosphere” where they have created the four seasons and from tropical to arctic conditions with the plants and animals that live in thoses different sections. In fact, you can grow a coconut tree or palm tree in Alaska or an apple tree in Miami or Hawai, but to “mimic” the growing conditions you need very expensive equipment as I said above.

As for zone 11, you will also need some equipment to give the tree a cold period every year otherwise it will die.

What is said above concerns all trees and shrubs like trident maple, vine maple etc.that are non-adapted or not hardy to climatic zone 1,2,3 and 4 . The information on hardiness for all trees can easily be found in the web.

I hope this important information will be usefull for those who live in the climatic zones concened.

Al Devaux, retired plant pathologist

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tuckerg

Al,excelent article.i enjoy your posts,keep at it.

ALDEVAUX

Thank you very much, tuckerg, I am glad to see that someone does not seem to think as another person in this forum told me : "that I trying to inform you that you are making groundless assumptions".
I was also happy to find this morning that two other plant pathologists from Minnessota (on the web) give the same type of information as mine :
http://www.na.fs.fed.us/spfo/pubs/h...non/non_all.htm

Best regards

Will_Heath

So Al, you are basically saying that if the plant is not hardy in your zone then you need to provide protection? And if I am understanding your post correctly, the physiological disease that killed your maple was simply winter kill?


Will Heath , used car salesman

Bonsainut

Saving the world one bonsai at a time,


good effort ALDEVAUX.

__________________
Keep growing,---'Nut



Lethal Use of Farce

ALDEVAUX

Will, what I am trying to say is that trees that are not hardy should have more than basic winter protection. They should have special protection in a cold room or in heated greenhouse.

Yes my maple did not survive the very low winter temperatures or sudden changes in temperature that occurred in 2004, enven though I thought I had given it more than the basic protection. It is definitely what is usually called winter kill which is a temperature stress for which the tree was not adapted.

ALDEVAUX

After what I said in my first post, I thought that some bonsaists might want to know why we call winter killing a physiological disease.

Well, from the definition given by plant pathologists, a plant disease is
in general, when the plant is "continuously disturbed by some causal agent that results in an abnormal physiological process that disrupts the plant's normal structure, growth, function, or other activities. This interference with one or more of a plant's essential physiological or biochemical systems elicits characteristic pathological conditions…" In other words it is when a diseased plant is incapable of carrying out its normal physiological functions to the best of its genetic potential, and what is most important to distinguish between a disease and a damage or injury is that a disease acts or takes a certain time to devellop compared to the damage which is sudden and instant. Cutting a branch or pinching their tips causes an injury or a damage to the tree, not a disease. Many physiological diseases are very difficult to identify because they can be caused by a lot of different factors or combinations , but the most important ones are caused by temperature stresses, insufficient light, nutritional troubles like deficiency of nutrients or their excess (salinity problems), wrong pH of the soil, excess or low soil moisture, air pollution, pesticides (especially herbicides) etc. A very common one on tropical bonsai is the yellowing and browning of some leaves before they fall due to either a sudden change in temperature, light intensity, soil moisture, nitrogen deficiency, or a cold draft near a window or a combination of them.

So, winter killing of a non hardy tree is caused by cold temperature stresses that disrupts the function of the normal physiological activity of the tree during a certain period of time. In fact it may take a few month or years for the tree to die depending on how hard the stress is.

I also found a bonsai site (in french) where it is said that japanese maples and other non hardy trees require to go to dormancy a period where the temperature is lower than 10-12 degrees celcius (50-55 degrees F), and the ideal temperature is about 5 degrees celcius (40 F) during the winter. Finally, the tree gets out of dormancy if it is kept at more than 10-12 degrees celcius (50-55 F) during 10 to 12 days. The bonsaist of the bonsai nursery I know has kept his beautiful non hardy bonsai in this way for more than years now. Here is the link for those who can read french
http://www.monbonsai.com/fr/entretien.htm

So, a good way to keep a japanese maple in winter to prevent dieback is to keep it in a cold room during the time the winter temperatures are too low before putting it outside.

Bonsainut

I still don't get it can you explain some more?

__________________
Keep growing,---'Nut



Lethal Use of Farce

ALDEVAUX

Bonsainut, can you tell me what is it exactly that you want me to explain?