Winter Burn

Robert Bishop 
Frederick County Master Gardener Program

Winter burn injury is leaf damage that is caused by cold winds which dry out the leaves of evergreens. There are products available which can reduce this injury when used properly. They are in a group of chemicals known as anti-desiccants or anti-transpirants and sold under trade names such as Wilt-Pruf, Nu-Film, VaporGuard, and Stressguard. The products create a barrier over the pores (stomates) in the leaves which allows the plant to breath but reduces water loss through transpiration (daily leaf sweating). Anti-desiccants can also be used when transplanting trees and shrubs and for prolonging the freshness of live foliage decorations like Christmas trees and wreathes.

Winter burn injury can take place whenever the soil freezes and wintery winds blow drawing moisture from leaves. Plant roots cannot uptake water from frozen soil to replace the losses experienced in the leaves. The longer these conditions exist, the more moisture is lost and death of leaf tissue results. Plants that hold their leaves (evergreens) over the winter are vulnerable, broadleaf types are more susceptible than the needle type evergreens due to the larger surface area of their leaves. The two most common months for this to occur in Maryland are January and February.

The location of plants in the landscape is an important consideration when deciding whether or not to apply an anti-desiccant. Windy sites are obviously more prone to this type of damage than protected locations. Soil moisture is also a factor, this was a very dry fall season, if you did not water in addition to the natural rainfall I suggest doing that now and using an anti-desiccant on vulnerable plants. In fact it is advisable to water problem plants during winter thaw periods. Use a pail for watering in winter. Pipes that supply hose bibs should have already been shut off inside to protect them from freezing and hoses should be stored indoors for the winter.

To prevent winter burn injury apply an anti-desiccant in late December and again in late January. One late fall application is not enough. Generally these products are applied to the foliage as a liquid, do not apply if temperatures will drop below freezing for 24 hours after the application. The second application is usually more difficult because it must be done within this temperature range "window of opportunity" to be effective. As always, read and follow the exact directions on the label for the particular product you have purchased.

Here is a list of evergreen plant material that can be susceptible:

  • Southern Magnolia

  • Rhododendrons and evergreen Azaleas

  • Cherry Laurel

  • Mountain Laurel

  • Japanese Pieris (Andromeda)

  • Aucuba

  • Ivy

  • Leucothoe. 

Also these plants can be affected but to a lesser degree: Hollies, Osmanthus, Heavenly Bamboo, Forsythia, Skimmia, Dwarf Sweetbox, Daphne, and Boxwood, conifers, especially when used as a wind break- Pines, Spruces, Cedars etc.

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