Released October 13, 2008
ST. PAUL, Minn. — This fall several tree species have shown signs of stress. Some of these signs include early leaf drop, browning of leaves or needles, abundant production of seed and leaf loss at the top of the tree. Trees that seem to be most affected are ash, maple, cedar and pine. Well established mature trees are also exhibiting signs of stress.
Multiple factors could be causing stress on trees this fall. These factors include stem girdling roots, tree planted too deeply, poor soils, drought, winter injury, leaf diseases and other factors. This year there were dry conditions in many parts of Minnesota. For the past few years, tree care experts have noticed a general decline in the vigor and health of many trees especially ash and maple cultivars. Mature trees should recover.
A general fall tree care recommendation for conifer trees and trees planted in the last three years is to water generously until the soil freezes. Since some areas of the state have been suffering from drought conditions for multiple years, watering and mulching in the spring may also be beneficial.
The best time to prune trees is during the dormant season from January to March. Flowering shrubs can be pruned in the summer after flowering.
Young maples may benefit from some kind of sunscald protection to prevent the bark from cracking this winter and spring. This protection is usually in the form of a plastic tube or tree wrap. These practices can also help in reducing winter animal damage. These protective structures should be removed in the spring.
Protecting trees from rabbits, mice, voles and deer is a major concern in some landscapes during the winter. If the bark is removed or severely damaged around the tree, it will die. Protective physical barriers such as hardware cloth or fencing may be a possibility in a small planting. Bud capping leaders with a paper cone or balloons on young conifer trees is common.
Odor, taste and visual repellents can be used to repel many wildlife species, but may have inconsistent effectiveness. Human hair, soaps, garlic oil, hot sauce and animal repellents can be applied to branches and foliage to discourage browsing. Weather, application frequency, animal population and feeding pressure affect the success of repellents. Some animals become desensitized to the repellent, so you may want to alternate repellents.
To learn more about these topics, look at the following websites:
- Prevention and Control of Wildlife Damage, http://icwdm.org/handbook/index.asp
- Forest Resources, Extension, http://www.forestry.umn.edu/extension/
- Bud Capping, http://www.dnr.state.mn.us/treecare/whitepine/tending.html
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http://www.extension.umn.edu/extensionnews/2008/extra-attention-for-trees.html
Contacts: Gary Wyatt is natural resources educator with University of Minnesota Extension.
Catherine Dehdashti, U of M Extension, (612) 625-0237, ced@umn.edu
