Questions on: Maple Leaf Problems
Ron Smith, Extension Horticulturist, NDSU Extension Service
Q: I planted a maple tree last fall. This year the new growth is yellow with small leaves. It also has some black, poorly developed leaves. What is wrong and can it be corrected? (Portland, N.D.)
A: It is most likely a soil pH problem. I doubt that you will be able to correct it because the problem showed up so early in the life of the tree. The tree also may have been planted too deep.
Q: I have enclosed a sample of my red maple's leaves that are starting to pale and get brown spots. (Fergus Falls, Minn.)
A: Your maple has terminal chlorosis. This could be brought on by a number of factors: a rising water table, root decay, a high soil pH (alkaline soil) or flooding during a critical part of the growing season.
The tree may hang on for a year or two before it dies. I have seen many heroic attempts to save them at this point, but none have succeeded. I suggest making plans to convert it to firewood. Sorry!
Q: I have enclosed a small branch from my red maple tree that was a gift 10 years ago. For the last few years the leaves have started to turn yellow and drop off. I have tried fertilizer spikes and iron granules, but I don't think it is helping. Also, is the white cocoon a limb worm? (Breckenridge, Minn.)
A: The tree was a thoughtful gift, but an inappropriate selection. This species is not well adapted to our area. The white cocoon on the limb is a cottony cushion scale insect. They usually get established on trees and shrubs that are under stress. Which yours obviously is.
I have enclosed an extension publication, "A Guide to Deciduous Tree Knowledge" (F-436), which should help you make better future selections.
Q: I have some Maple trees that are full of pink and green spots, could you tell me what is wrong with them? We really like the trees and would like to save them if possible. (Platte, S.D.)
A: Your Maple has a bladder gall caused by a mite invasion which took place about two months ago. These critters do only cosmetic damage and there is nothing one can do now. They can be controlled somewhat by spraying the tree with dormant oil spray next spring as the buds are beginning to swell (not as they are beginning to open.)
Q: I am having problems with my maple tree in the back yard. The leaves are yellow and have large black spots on them. They fall off
all the time as if it is turning fall. I don't know how old the tree is because we just moved into this house this February. I don't know
what kind of maple it is either. (E-mail reference)
A: It sounds like your tree has a disease known as tar spot, which is not known to be fatal, just disfiguring. To control, rake all fallen leaves this autumn and dispose. The following spring apply Bordeaux mixture every two to three weeks during leaf emergence.
Q: Can you tell me why the leaves are falling off of my maple trees? They turn yellow and fall down, but the remaining leaves appear healthy. Also, the bark is falling off of the trunk portion of my largest maple tree, but otherwise it seems to be healthy. (Pelican Rapids, Minn.)
A: Concerning your maple trees, I am sending you NDSU Extension Service publication F-1192, "Insect and Disease Management Guide for Woody Plants." It is an excellent, descriptive resource that should help you determine what is wrong with your trees. As for the bark, that is usually normal on older trees, especially when the weather conditions change so radically.
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