These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Winter Winds, Cold and Plants October 23, 1997 Winds and cold temperatures are signaling that winter is not far off. Wind and cold temperatures not only make things uncomfortable for us, but can damage trees and shrubs over the course of the winter. Prolonged periods of near zero or below zero temperatures can injure many trees, particularly those marginally hardy for our area. Buds, twigs, and entire branches may be killed. In spring, typical low temperature injury may show up as the lack of flowering, or a plant appearing to resume normal growth and then suddenly wilting and collapsing. Sudden cold after mild weather can magnify damage. All species of trees and shrubs entering winter without adequate soil and tissue moisture or with low food reserves become more susceptible to low temperature injury. In addition, problems such as improper pruning or fertilizing, or defoliation during the growing season (insects, disease) may increase susceptibility to low temperature injury. Winter winds can cause desiccation injury to plants, causing above ground plant parts to dry out because water cannot be replaced from frozen soil. Evergreens of all types are most susceptible. On needle evergreens, desiccation injury shows up as yellowing or browning of needles during winter or early spring (some varieties naturally do this but quickly recover in spring). On broadleaf evergreens, typical injury will be scorching or browning of the foliage. Susceptible species include rhododendron, boxwood, holly, and some euonymus. There are ways to reduce desiccation injury of evergreens. Locate plants in areas protected from north and west winds during winter. Foundation plantings with south or west exposures can be poor locations due to the drying effects of the sun. Plants existing in exposed areas or along a south or west foundation may be wrapped in late fall with burlap or canvas materials to slow desiccation. Commercially available anti-transpirants can be sprayed on susceptible plants in late fall (temperatures above freezing) to help prevent drying out. As mentioned over the past few weeks, adequate watering of plantings throughout the fall is a key to preventing this damage.

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