As we prepare for the upcoming winter, remember that winter is an excellent time for tree pruning – in fact, it is the preferred time to prune many tree species. During the winter months dead, dying and diseased limbs can be easily seen and removed. If you have been thinking about talking with your “tree guy” now’s the time to call. But there are some other reasons to get in touch with an Arborist this winter – winter drying and the associated cold weather damage can be addressed before it becomes a major problem.
Winter drying, winter injury and winterkill are synonymous terms applied to a foliage disorder common on evergreens in northerly climates. Winter drying typically occurs on warm, windy days following a period of cold (subfreezing) weather. Under these conditions, moisture loss through the foliage is greatly accelerated, while replacement of this water is restricted because the soil is either frozen or too cold to permit water absorption throughout the roots. Desiccation and subsequent death of the foliage often results. In severe instances, buds may also be affected leading to the death of twigs and entire branches. Shallow-rooted evergreens, which characteristically retain their lower branches, are very sensitive to winter drying. Recently transplanted evergreens – including broadleaved evergreens like Rhododendron, Holly and Azalea – are particularly susceptible to this disorder. The incidence of winter drying is greatest on poorly drained sites and in open, unprotected areas, which are subject to full sun and drying winds.
As usual, planting the right tree in the right place is the best way to help prevent this disorder. Judicious selection of plant species and planting sites is essential in preventing winter drying. Susceptible evergreens should not be planted on poorly drained sites or open, windswept areas. If you have already planted and think winter damage could be a problem, windbreaks either temporarily constructed with burlap or permanently supplied by living trees and shrubs can reduce the effects of drying winds. Application of anti-transpirants can also decrease the drying effects of wind and sun by restricting transpirational moisture loss. Consult with an Arborist before applying anything to your trees as anti-transpirants are not recommended for all species.
Some other things to consider before the real cold of winter sets in:
- Maintaining the vigor of ornamentals through fertilization, pruning and watering during dry periods is helpful in preventing this disorder.
- Ensuring that evergreens are well watered in late fall is particularly important.
- Mulch placed around susceptible species help slow soil moisture loss as well as restrict soil freezing.