Remember To Prune Trees Before Spring Arrives: Mendota Heights

From the City of Mendota Heights:

Late winter is the best time for pruning of most trees. Pruning at this time leaves wounds exposed for only a short time before new growth beings in the spring. However, one of the greatest advantages of pruning during this time is to avoid tree diseases. Below are some common tree diseases, and when to avoid pruning to prevent them.

• Emerald Ash Borer (EAB): Only prune or remove ash before the EAB beetle becomes active. This is typically May 1st, but differs with weather conditions. If removal is necessary, chip at least 1” of outer bark on-site, and transport to the nearest facility that can process the material quickly. REMEMBER: Dakota County is a Quarantined Area for EAB. Ash wood cannot be transported out of the quarantined area without permission from the Minnesota Department of Agriculture. For more information on EAB: https://www.mda.state.mn.us/best-management-practices-eab
• Oak Wilt: Do Not prune oaks between the months of April – October. Oak wilt is caused by a fungus that spreads by root-grafting or by insects. Symptoms include wilting, brown leaves that spread from the tip of the leaf to the base, spore mats, and discoloration of the bark.
• Cankers: Cankers are an infection in the shoots and branches of trees. They can girdle the stem, resulting in death of growth above the canker. To avoid stem cankers, only prune during dormancy.
• Blight: Blight, or leaf spot disease, is caused by pathogens that create dieback of young shoots, and is common on Populus species (poplar, aspen and cottonwood), but can also affect other species including crabapples, apple, mountain ash, and hawthorn. To avoid, only prune during dormancy.

General Pruning Guidelines:

• Prune at branch junctions, and leave a 1/4” ‘stub’ beyond the bud, instead of making a flush cut.
• Remove outside branches instead of inside branches whenever possible, to encourage upward growth.
• Use sharp, clean tools.
• Remove any diseased, broken, dead, or downward-growing branches.
• Remove any branches that are rubbing, touching, or crossing another branch.
• Remove and suckers coming from the roots of the tree or low on the trunk.
• Use good judgement and put safety first – if you cannot safely remove a branch from the ground, call a tree care professional.

This press release was produced by City of Mendota Heights. The views expressed here are the author's own.