I will try and add a photo of the leaves. Looks like it did not attach the first time. - Ask Extension
Hello--I have a Korean maple, about 5 feet tall. It is getting yellow and then red leaves that are dropping off, on various branches. The veins stay...
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I will try and add a photo of the leaves. Looks like it did not attach the first time. #196320
Asked July 02, 2014, 3:02 PM EDT
Hello--I have a Korean maple, about 5 feet tall. It is getting yellow and then red leaves that are dropping off, on various branches. The veins stay green, and the leaf turns yellow. I will include photos.
Any ideas?
I am concerned because I also have a Japanese Empower 1 maple about 15 feet down this same border, and a new Korean maple 'Arctic Jade' which I planted in front of the house this spring, and paid dearly for. I am concerned that the "disease" might infect the more costly specimens in my collection.
Thank you.
Kay Wolfe
St Louis Park
PS I attached 3 photos. If they did not come through, let me know.
Hennepin County Minnesota
Expert Response
Hi,
I have some ideas but am checking with some other Master Gardeners. I will be back with you as soon as I can.
I have some ideas but am checking with some other Master Gardeners. I will be back with you as soon as I can.
Now some of the leaves are just curling and drying up and not turning red. Photos added.
Thank you for your question.
I believe your Korean maple (Acer pseudosieboldianum) is suffering from environmental stress coupled with some exposure to afternoon sun as it's gotten taller and the direction of the sun changed with the season. Symptoms of stress in maples is seen as premature reddening leaves, wilting, brown tips, weak sprouts at the base of a tree, canopy dieback. As per our Extension publication http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/shade-tree-decline/ there can be many reasons for stress. Flooding or change in the water table can cause stress as can drought conditions. Trees planted too deeply can result in girdled or restricted root development. If your tree is grafted, the graft may have failed. You don't say how old this tree is, but if it was recently planted / moved to the current site, it may be suffering transplant stress as well.
U of M Extension does not have much information on Korean maples specifically, but there was a statement about avoiding afternoon sun: http://www.extension.umn.edu/Garden/yard-garden/trees-shrubs/small-maples-for-minnesota/. It appears in your photos that the upper leaves which are shown to be in the sun, are also the leaves that are drying up.
Minimize stress by watering and mulching your tree, and being sure it is getting the proper nutrients it needs through fertilization. Also, protect the trunk in the winter from animal browsing and prune the tree for proper form and structure.
If your tree continues to decline, I recommend contacting the nursery where you purchased it for additional advice or replacement.
Best of luck to you and thanks for contacting Ask an Expert.
I believe your Korean maple (Acer pseudosieboldianum) is suffering from environmental stress coupled with some exposure to afternoon sun as it's gotten taller and the direction of the sun changed with the season. Symptoms of stress in maples is seen as premature reddening leaves, wilting, brown tips, weak sprouts at the base of a tree, canopy dieback. As per our Extension publication http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/shade-tree-decline/ there can be many reasons for stress. Flooding or change in the water table can cause stress as can drought conditions. Trees planted too deeply can result in girdled or restricted root development. If your tree is grafted, the graft may have failed. You don't say how old this tree is, but if it was recently planted / moved to the current site, it may be suffering transplant stress as well.
U of M Extension does not have much information on Korean maples specifically, but there was a statement about avoiding afternoon sun: http://www.extension.umn.edu/Garden/yard-garden/trees-shrubs/small-maples-for-minnesota/. It appears in your photos that the upper leaves which are shown to be in the sun, are also the leaves that are drying up.
Minimize stress by watering and mulching your tree, and being sure it is getting the proper nutrients it needs through fertilization. Also, protect the trunk in the winter from animal browsing and prune the tree for proper form and structure.
If your tree continues to decline, I recommend contacting the nursery where you purchased it for additional advice or replacement.
Best of luck to you and thanks for contacting Ask an Expert.
Do you think there is any chance this is Verticillium wilt on my Korean maple?
The tree is small, and was planted as a clump in 2010. The rabbits have trimmed it up into tree form. It is partly shaded by a large elm, but does get some afternoon sun.
Thank you.
Thanks for your question.
The rabbit damage may have girdled the tree as well, causing interruption of transfer of nutrients and water from the roots to areas of the tree and thus resulting in dieback. It appears to be a fairly small tree, so any damage from girdling could be significant.
It's hard to say whether your tree is suffering from verticillium wilt by just seeing the pictures and description. Here is our diagnostic tool about issue with maple including VW: http://www.extension.umn.edu/garden/diagnose/plant/deciduous/maple/leavesbrown.html
For more details, I've included the publication on verticillium wilt. http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/verticillium-wilt/. Note that black streaking in the vascular tissue is a diagnostic.
If you compare the information and would like our plant disease clinic to make a diagnosis, you may contact the clinic about bringing in a sample: http://www.pdc.umn.edu
You may also choose to hire an arborist to examine your tree. Here is a link to the International Society of Aboriculture and a way to find a specialist in your zip code area: http://www.isa-arbor.com/findanarborist/arboristsearch.aspx
Best of luck and thanks for contacting Ask an Expert.
The rabbit damage may have girdled the tree as well, causing interruption of transfer of nutrients and water from the roots to areas of the tree and thus resulting in dieback. It appears to be a fairly small tree, so any damage from girdling could be significant.
It's hard to say whether your tree is suffering from verticillium wilt by just seeing the pictures and description. Here is our diagnostic tool about issue with maple including VW: http://www.extension.umn.edu/garden/diagnose/plant/deciduous/maple/leavesbrown.html
For more details, I've included the publication on verticillium wilt. http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/verticillium-wilt/. Note that black streaking in the vascular tissue is a diagnostic.
If you compare the information and would like our plant disease clinic to make a diagnosis, you may contact the clinic about bringing in a sample: http://www.pdc.umn.edu
You may also choose to hire an arborist to examine your tree. Here is a link to the International Society of Aboriculture and a way to find a specialist in your zip code area: http://www.isa-arbor.com/findanarborist/arboristsearch.aspx
Best of luck and thanks for contacting Ask an Expert.
