tt-159 BY DON MEEHAN

SERIES ON WINTER INJURY OF LANDSCAPE PLANTS
Part 4 - What to do About Injury

Plants in the Pacific Northwest may suffer injury due to extremely cold temperatures or other types of winter weather. These past few winters have been especially severe. This column will be devoted to a four-part series on winter injury of landscape plants. The first parts covered were "How Winter Injury Occurs", "Types of Winter Injury", and "Symptoms of Winter Injury". Today's column is Part 4 of the series. If you missed the first three parts you can call the Island County/WSU Extension Office at 679-7327 to request a copy. PART 4: WHAT TO DO FOR WINTER-INJURED PLANTS 1. Don't do anything until late spring when new growth begins on the live wood, and does not begin on the dead wood. Then prune to remove dead wood. Before doing anything, check to be sure the crown is alive. 2. Prune properly. Don't leave stubs. Prune back to live, green, healthy wood. Prune to a bud, stem or trunk. Give a suffering plant a chance to become healthy again. Prune it right. Only prune out dead and severely damaged wood. Do not prune live wood. The larger the leaf surface area of the plant, the better it can manufacture food and grow new tissues. 3. Water properly. Make sure the plant is not further damaged by drought. Pay special attention to evergreens and plants situated under the eaves. Water properly throughout the spring, summer, and fall. Do not overwater (See Extension Bulletin 1090, Watering Home Gardens and Landscape Plants, available from the Extension office). 4. Fertilize? Experts disagree about the advisability of fertilizing winter-damaged plants. If the roots have been injured, there is a concern that fertilizer salts could injure roots. Also, fertilization would stimulate top growth that the damaged root system may not be able to support. Some feel that stimulation of growth may draw on the energy reserves that the plant needs to help it overcome the winter damage. Other experts feel that fertilization is beneficial. Stimulation of top growth increases the leaf surface area which manufactures food and helps grow new tissue. Fertilization is definitely recommended if the soil lacks adequate amounts of basic plant nutrients. Where the nutrient status of the soil restricts normal plant growth, fertilizer should be applied in the root zone area. 5. Mulch with a loose organic mulch to maintain soil moisture and to protect from extremes of temperature. 6. Remove as much of the fruit as possible to allow a fruit tree to puts its energy into overcoming the winter injury rather than producing fruit. Allowing fruit to be produced on a fruit-bearing tree will further weaken it. 7. The best thing you can do for your injured tree or shrub is to avoid further stress during the coming season by giving it special attention and care. Avoiding Winter Injury--Residents of the Pacific Northwest can expect plant-damaging weather in future years. Our best insurance against winter injury is to: 1. Select plants hardy for the local climate and soil conditions. 2. Situate evergreen plants in the landscape to minimize their exposure to sun and wind. If this is not possible provide a windbreak or shading during winter months. 3. Wrap the trunks of young and recently transplanted trees with a white or light colored bark wrap in the fall, especially young smooth and dark-barked trees. 4. Keep plants in healthy condition. 5. Do not fertilize, prune or water heavily late into the season. This can encourage late season growth that may not acclimate well in the fall. 6. Water landscape plants, especially evergreens, to keep the soil moist during late fall and early winter dry spells. Pay close attention to plants under overhangs or other places where they may not be receiving natural precipitation. Don Meehan is on the faculty at Washington State University working in Island County as a County Extension Agent. He is located at the Coupeville WSU Extension Education Center. The phone number is 679-7327. Cooperative Extension programs are available to all without discrimination. This information has been provided by Sharon J. Collman, WSU County Extension Agent and Ray Maleike, WSU Extension Horticulturist.




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