Winter may not seem like the ideal time for forestry, but Lake Zurich's arborist, Shawn Walkington, says the dry, frigid temperatures and the lack of leaf cover make it the best season for tree maintenance.
Walkington, who overseas the health and well-being of the village's nearly 8,000 trees, said the safest time to trim most trees is in winter. He recommended that property owners check their trees each winter for broken branches and branches that have grown together, as well as for overall form and good growth.
"For trees, the colder it is, the better," Walkington said.
Because fungus, bacteria and bugs aren't active in the cold weather, winter is the best season to remove branches, he said. Oak trees especially should be trimmed in winter, because they are susceptible to oak wilt, a potentially fatal fungus that can enter trees through the open wounds made by saw cuts.
However, because of this winter's inconsistent temperatures, with freezes and thaws within a single week, Walkington said that all bets are off. Although he still suggested that trees be trimmed this winter, come spring, Walkington expects to see a lot more bug, bacteria and fungal infestations in trees.
"I'm guessing we'll see a lot more emerald ash borer this year and Japanese beetle," he said. Walkington estimated that about 75 percent of Lake Zurich's 2,900 ash trees are infested with emerald ash borer, a green beetle whose larvae "bores" into the trunks of ash trees, potentially killing them. The less harmful Japanese beetle doesn't destroy trees, but does eat their leaves. Pesticides should be applied in fall or spring when temperatures warm up to 40s or 50s and trees come out of dormancy.
Of course, homeowners can eyeball their trees and tell if there are broken branches. But for a comprehensive assessment of the health of their trees, as well as the actual trimming, Walkington strongly suggested that people should hire a professional arborist, certified by the International Society of Arboriculture. Usually only an arborist has the training and experience to tell if there are dead branches or weak spots, and generally if the tree doesn't look right.
If trees are pruned in the wrong spot or in the wrong way, they may not heal correctly, he said. Likewise, trees should never be "topped," by lopping off the top to shorten it. Not only do they wind up just an unattractive stub, but the technique weakens trees, because the shoots that eventually do emerge are not strong. An arborist can reduce a trees height by selectively cutting and removing branches without endangering its health, he said.
"You can get anyone with a chainsaw to trim your trees, but they may use improper pruning techniques, which may be bad for your trees," Walkington said.
The major exception to the winter pruning rule is most flowering trees, which should be pruned soon after they drop their blooms, because their blossoms are set the previous year. Homeowners—or arborists—should also check the position of their trees on the lot to make sure they are not growing too close to a house, sewer system or utility line.
Walkington said he and his staff are available to go out and check on trees on private property, but they cannot treat or remove them. Walkington only cares for those on village property, such as parkways and public parks.