Pruning Trees in March Promotes Health, Beauty
Remove Narrow Crotches to Improve Structure When Trees are Dormant
Work done in March before leaves bud out promotes quicker healing and greatly reduces the likelihood of tree-boring insects honing in on fresh pruning cuts.
“March is a good time to prune because you don’t have the leaves to try to see through,” said Brian McKenzie, a manager with Bartlett Tree Experts.
McKenzie recommends homeowners inspect trees for broken or dead limbs which are sometimes indicated by peeling bark. Remove suckers growing around the trunk and water sprouts from lateral branches; they rob energy from the rest of the tree.
Trees require pruning to remove dead or damaged branches, to redirect growth or to prevent future problems, such as limbs that may eventually press against the house. For a comprehensive manual on how to prune trees, visit the federal government’s Web site pueblo.gsa.gov/cic_text/housing/prune/prune.htm
Heavy bleeders
Homeowners pruning heavy bleeders like birch and maple often are alarmed by the flow of sap from fresh cuts. Don’t worry, McKenzie said. Bleeding is perfectly natural and does not harm the tree.
The real harm comes from pruning certain trees after April 1, specifically oaks, American elms, birches and fruiting trees.
Perilous pruning
Freshly pruned trees release a hormone that is picked up by insects indicating the tree is under stress. Pruning while the tree is dormant allows healing before potentially damaging insects emerge, McKenzie explained. Certain beetles use the fresh wound to enter a tree’s vascular structure, causing its decline and death.
Structural pruning
“Probably the biggest thing the public misses is structural defects; that is one of the things we are constantly looking to correct, particularly on smaller trees,’’ McKenzie said.
Structural defects include multiple leaders and narrow branch angles which arborists call crotches. Also look for branches rubbing against one another; one needs to be removed.
McKenzie said he prefers to remove co-dominant leaders at the same time, even if the tree initially looks a little sparse. New growth eventually fills in the bare spots.
“We have to balance what is best for the tree and how much change in aesthetics a client can tolerate at a time,’’ McKenzie said. “We tend to want to do more than a homeowner wants us to do at one time. The drawback is we have to come back.’’
Training trees
The younger a tree is, the more receptive it is to corrective pruning. Branches connected to the trunk in a tight V-shaped angle should be removed before they grow too big. The narrow-angled branch presses against the trunk, creating almost a wedge-like affect, making it vulnerable to splitting.
Those with a ‘U’ or ‘L’-shaped union are the ones to keep because they are structurally sound.
“The sooner in the tree’s life you can get the proper structure established, the more cost effective it becomes,” McKenzie said. “If you don’t get those problems corrected in the first 15 to 20 years in a tree’s life, you may lose pruning as an option.’’
Strong limbs
Branches with a wider angle become stronger with each season as overlapping growth provides another layer of structural support.
“It is a natural way to grow strong,” said Vic Foerster, an arborist with West Michigan Tree Services. “With every year, you get this overlapping to give it strength. This natural engineering structure is incredibly strong.'
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