NDSU Extension - Mercer County


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Good Time of Year to Prune Your Trees

pruning trees, pruning

Submitted by Craig Askim, Extension Agent/Agriculture and Natural Resources

Why Prune?

The leading answer to this question should be for safety reasons. Remove branches that could fall, or any branches or shrubs that interfere with the line of sight on driveways or streets. Homeowners should not get involved in pruning that requires climbing or working anywhere close to power lines. Allow trained professionals to do that work.

When planting a tree, think about how that tree will form as it grows: Will it stay within the available space at maturity? Will the branching characteristics have the strength to develop a form suitable for the site? Many times, future maintenance can be reduced significantly if you select the right tree or shrub for the particular location. Other reasons for pruning are disease or insect control. Pruning for diseases such as black knot and fire blight is common in trees in Mercer County and needs to occur at this time of the year to reduce disease spread.

Always cut 10 to 12 inches below the visible symptoms of these pathogens, preferably during dormancy, and wipe the pruning shears with an alcohol-soaked, hand-sanitizing cloth or a 10 to 20 percent bleach solution to help prevent the spread of these fungal and bacterial pathogens.

Selecting resistant species, limiting nitrogen fertilization or any practice that produces excessive succulent growth will go a long way in minimizing disease problems with most woody plants.

When to Prune

Much of the pruning that landscape plants need can be carried out in late fall or early winter once the trees start to become dormant. By pruning at this time of the year you reduce the risk of insects and fungi activity. This is true for deciduous and coniferous woody plants.

Some shrubs bloom only on the previous season’s growth. For example, if you want them to re-bloom the following season, you should complete the pruning immediately after the blooming period is over. Pruning these shrubs while still dormant removes potential flowering branches for that growing season.

Evergreens generally have a longer pruning season than deciduous plants. In addition to early spring and midsummer, pruning after new growth has hardened is acceptable for pines and spruce trees.

When a branch is causing safety concerns, you can override the seasonal recommendations for pruning. Go ahead and prune or have the branch pruned by a professional arborist. Safety may be an issue when branches are threatening to fall and cause serious damage to structures or harm to individuals, or they are blocking a view of an intersection or moving traffic.

Newly planted trees should not be pruned immediately. For the first year at least, allow all the branches with foliage to remain; the more branches the tree has, the more carbohydrates it will make during photosynthesis and the faster the tree will recover from transplant shock. After the second or third year in a landscape setting, you can do annual maintenance pruning and remove the “temporary branches.”

Safety Precautions Concerns When Pruning

While chainsaws can make the pruning work go quickly, they often are used without any consideration for safety. Pruning for many is not an enjoyable job and you may want to get it done quickly, which can lead to problems. You should wear proper protective gear, including a hardhat/helmet, eye protection, ear protection, gloves and heavy pruning chaps, when using a chainsaw.

Don’t cut branches that are above shoulder height, and both of your feet should remain on the ground. You should leave any pruning up in a tree that requires the use of a chainsaw to a professional arborist.

For more information on pruning or general tree care, call your local county Extension office

Source: Todd Weinmann, NDSU Horticultural Agent Cass County and Joe Zeleznik, NDSU Extension Forester

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