Winter Damage Bites Twice

This spring, winter damage manifested in an abundance of ways:

• Western arborvitaes, ‘Green Giant’ hybrid arborvitaes, some juniper varieties, Scots pines, limber pines, Austrian pines, and other needle evergreens showed brown patches or dead branches.
• Broadleaf evergreens such as boxwoods, hollies, vincas, Euonymus and Pachysandra groundcovers were damaged. Pachysandra, particularly, was often hit hard.
• Trees with pre-existing conditions such as Diplodia tip blight infections in pines, Cytospora branch cankers on spruces, magnolia scale damage on magnolias, Japanese tree lilacs with verticillium wilt infections, girdling (strangling) root conditions on maples and others often had portions of their crowns die.
• Half-hardy trees like Japanese maples, some redbud varieties, magnolias, some hydrangea varieties, peaches, ornamental pears, etc. were damaged as well.
• Some perennials were lost or came up weaker than usual. Damage was not limited to small specimens—some larger trees, even natives like sugar and silver maples, showed branch/ crown damage. The main culprit was the second “open winter” in a row, helped by a very dry fall and winter

The “Open Winters” of 2023-2024 and 2024-2025

Open winters have little to no snow cover. The ramifications of this were presented at the Wisconsin Arborist Association Annual Conference in February 2022. The lack of insulating snow cover allows faster and deeper frost penetration during polar vortexes and can damage or kill some tree roots. I always knew this was a problem for half-hardy trees like magnolias or Japanese maples but learned that it can be very significant for native trees, too. Even they may not be able to adjust fast enough and can get damaged root tissues. This spring was surprising in that the damage seen was much more than last spring, which also followed an open winter. Making sure trees receive 1″ of water per week is imperative to enable regrowth. In fall, measures to help trees replace or build new feeder roots will compensate for this stress and damage. These measures include fall fertilization with root biostimulants, root biostimulants with systemic fungicide, compost tea, and mycorrhizal root inoculation. Pruning out the damage will help aesthetics and restoration. Call Wachtel Tree Science to help your trees recover and maintain their beauty.

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