bonsaiTALK Community - View Single Post - An important Physiological disease of japanese maple

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.

4-Feb-2005	#7
ALDEVAUX bonsaiTALK Master Join Date: Mar-2004 Location: St-Hyacinthe, P.Québec Country: CANADA USDA Zone: 4 AHS Heat Zone: ? Posts: 442	Physiological plant diseases 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.