Q&A: Fall Tree Care
Q: Is fall a good time to prune trees?
Experts generally agree that fall is not a good time to prune trees, because pests and diseases that can infest pruning cuts may still be active in fall. In addition, according to Eric Draper, Ohio State University extension arborist, pruning in fall can delay dormancy and result in winter damage. "The absolute best time to begin pruning is when the plants have completely shut down and have gone totally dormant for the winter," Draper says. "This usually occurs after all of the leaves have fallen off of the plants and the treees have been exposed to three or four bouts of really cold temperatures and hard freezes."
Keep in mind that it's best to use a light touch when winter-pruning spring-flowering trees and shrubs, such as dogwoods, redbuds, and rhododendrons. These plants hold flower buds over winter, so pruning may reduce spring blooms. A few tree species, such as birch, walnut, and some maples, bleed sap in spring from pruning cuts made in winter or early spring. This bleeding may not be aesthetically pleasing, but it's usually not harmful to the tree.
Q: What should I do to protect trees from winter damage?
One of the most frequent winter problems is sunscald.This happens when late winter or early spring sunlight warms a tree trunk, causing the tissue to "wake up" prematurely from dormancy. Once this happens, the plant is more susceptible to subsequent cold temperatures. According to Robert Cox, Colorado State University extension agent, "Sunscald is more of a problem where winters are sunny and cold, and it only occurs on young, thin-barked deciduous trees with significant southern, southwestern, southeastern, or western exposure." Examples of susceptible trees include honeylocust, willow, mountain ash, fruit trees, maples, and ashes.
Sunscald is preventable by wrapping trunks of young trees in crepe paper tree wrap in November and removing the paper in April. Cox says another approach is to lean a board against the south-facing side of a tree trunk to keep it shaded during winter.
Another common winter problem is gnawing from animals, particularly rabbits. Hardware cloth or chicken wire around the trunk will stop the hungry pests. Keep in mind that gnawing often occurs when food is scarce due to snow cover. So if you live in a climate where snow accumulates on the ground, you'll be wise to protect trunks up to 3 feet.
Q: Is fall really a good time to plant trees, or are nurseries just telling us that so they can get rid of excess stock?
Yes, it is a good time to plant. And end-of-season nursery clearance sales are hard to pass up, but be sure to jump on them early. "September and October are ideal for planting in the northern U.S., because the soil is still fairly warm and roots can still grow. But planting in November and December is risky," says Doris Taylor, plant clinic manager at Morton Arboretum in Lisle, Illinois. There are some important exceptions, Taylor says: "Japanese maple, birch, redbud, magnolia, and illow all do better with spring planting."
Fall is also a good time for planting in the southern U.S., Taylor says, and it's safe to continue to plant through winter, given the relatively warm temperatures. Regardless of where you live, Taylor recommends two things for planting success: "Water, and a layer of mulch around the base of the tree."
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