Landscape and Nursery - Winter Dessication

Winter dessication is a common problem in landscape and nursery plants. The following is a short article on the subject.

Winter desiccation is not considered a direct result of low temperature but originates from the interaction of temperature and wind. As the name implies, winter desiccation is actually a form of drought stress. Desiccation occurs when water absorption by the roots can not replace water loss through the foliage, buds or stems. Transpiration and evaporation from plant parts increase when temperatures rise above freezing. This is especially true on bright, sunny, windy days. If soils are frozen, water absorption can not replenish plant tissue moisture, and dehydration and eventual desiccation injury occur.

Signs of desiccation begin with leaf curl or wilting, and progress to a browning of leaf margins and/or bud scales. If conditions are severe or persistent, browning will consume the entire plant part. If snow cover is present, a tell-tale snowline above which damage occurred can be observed on the plants. Desiccation usually affects the foliage of broad- and narrow-leaved evergreens; buds and stems for the most part are not affected unless adverse conditions are prolonged or compounded by freezing injury. Desiccation injury varies with plant species, plant part, soil moisture content, depth of frozen soil, snow cover and wind velocity. Desiccation is common on narrow- and broad-leaved evergreens.

In this area, it occurs for the most part when the depth of frozen soil increases in mid- to late winter. Desiccation injury can be minimized or prevented by protecting plants with screening or applying an anti-transpirant. Wrapping or screening not only protects from wind but helps minimize the degree of temperature fluctuations on the plant parts. Wrapping protects the entire plant; screening is usually positioned to intercept prevailing winds. Wrapping may be the smart horticultural alternative on prized ornamentals or in high-profile landscapes. Anti-transpirants are another viable means of protection, but keep in mind that they must be applied and allowed to dry at temperatures above freezing. Application should be made before we anticipate injury, which is early to mid-January. A good time to consider applying anti-transpirants is during our typical January thaw. Degradation of the anti-transpirant due to weather may require reapplication to extend the protection through the critical period.

In nurseries, using overwintering coldframes covered in white plastic film to protect sensitive plants is the common method to avoid winter dessication.



Information and photo from a section of "Abiotic Plant Disorders - Symptoms, Signs and Solutions A Diagnostic Guide to Problem Solving" by Robert E. Schutzki and Bert Cregg, Departments of Horticulture and Forestry, Michigan State University Michigan State University. Go to http://www.ipm.msu.edu/cat08land/pdf/9-19abiotic.pdf for the full factsheet with photos.