AMES, Iowa – As leaves and temperatures fall, trees and shrubs in the home landscape become increasingly at risk for damage from animals, snow load, salt, sunscald and desiccation. Fortunately, there is still time to protect trees and shrubs from winter damage.
Aaron Steil, consumer horticulture specialist with Iowa State University Extension and Outreach, provides tips for preventing tree and shrub injury this winter in a guide from the Home and Horticulture Pest News website.
For many Iowans, damage from hungry wildlife during winter is a primary concern. The usual suspects, deer and rabbits, tend to feed on trees and shrubs during periods of prolonged snow cover, when food is scarce. Rabbits often damage trees and shrubs by feeding on the inner bark of the plant, which disrupts the flow of food from the top of the tree to the roots. On the other hand, deer tend to strip foliage from the lower branches of evergreen trees such as arborvitae and pines.
According to Steil, the best way to prevent damage from occurring is to place a physical barrier around trunks or lower branches, preventing wildlife from accessing vulnerable plants.
To prevent deer damage, protective wrappings should be at least 6 feet tall. “Tubes, wraps, wire fencing and wire cylinders can be placed seasonally around individual trees and shrubs to physically exclude and prevent deer from browsing,” writes Steil. “They are most effective on smaller, younger plants that are more susceptible to significant damage from deer feeding.”
To prevent rabbit damage, chicken wire or hardware cloth fencing at least 24 to 36 inches tall should be wrapped around the base of the plant. “To prevent rabbits from crawling underneath the fencing, pin the fencing to the soil with U-shaped anchor pins,” he adds.
Steil also notes that certain species of tree and shrub are more susceptible to rabbit and deer damage, and these species should be prioritized. A list of plants susceptible to rabbit damage is available from the Extension Home and Horticulture Pest News Website, as is a list of plants susceptible to deer damage. Visit the article How to Protect Trees and Shrubs from Animal Damage Over Winter for more information on managing and preventing winter damage due to wildlife.
Snow and Ice Injury
As heavy, wet snow accumulates on branches, it can cause them to bend, buckle and snap. To remove snow, gently shake the tree or shrub or use a broom to sweep the snow off, being careful to sweep with an upward motion to prevent further stress on the branches. Small evergreens, such as arborvitae, can be wrapped with twine or rope in the fall to prevent snow from accumulating.
When it comes to ice damage, there is little that can be safely done. For smaller trees and shrubs, branches laden with ice can be gently propped up to ease stress. For larger trees, however; Steil notes that any attempt to remove ice will likely result in more harm than good.
“Don't attempt to remove the ice by beating the branches with a broom or rake. This will only cause greater damage,” he says. “Individuals should stay away from large, ice-laden trees, as they can be severely injured or killed if a large tree or branch were to suddenly crash to the ground while underneath it.”
While de-icing salts are important for preventing injury due to slips and falls, it is essential that they are applied only as needed, since these salts can cause damage to concrete and landscape plants. To avoid this damage, Steil suggests that homeowners wait until precipitation has ended, then remove as much snow and ice from concrete surfaces as possible before applying salt. Salt can also be mixed with abrasive materials, such as salt or kitty litter, at a ratio of one pound salt to fifty pounds abrasive material to decrease the risk of damage.
For more information on de-icing salts and the symptoms of salt damage in plants, visit the article Using Deicing Salts in the Home Landscape.
Sunscald and Desiccation
Evergreens can lose a significant amount of water through their leaves during the winter due to strong winds and intense winter sun. Once the ground freezes, these plants can no longer take up water to replace what is lost through the leaves, leading to winter dieback. To prevent desiccation injury, susceptible plants should be thoroughly watered in the fall until the ground freezes. Screens or shields can also be constructed to deflect sun and wind during the winter.
According to Steil, intense winter sun can also result in sunscald, which is characterized by sunken, dried or cracked areas of bark, typically on the southwest side of the tree. The warm sun causes areas of the bark to unfreeze, but as the sun sets and temperatures fall, the tissue refreezes and is killed. To prevent this damage, wrap trees with plastic guards or tree wrap in the fall, then remove the wrapping in spring.
The winter months can be a stressful time for trees and shrubs in the home landscape. However, through mindful management, the effects of this stress can be managed to ensure that landscape plants thrive year-round. For more information on preventing winter injury, visit the Home and Horticulture Pest News website or contact Steil at firstname.lastname@example.org.
Shareable photo: Deer damage to yew.