What is Sunscald?
Sunscald can occur when the bark of a tree warms in the sun and dormant bark cells suddenly become active. When temperatures drop at night, the active cells become damaged. The cells are protected when they are dormant but are vulnerable to the colder temperatures in the active state.
When sunscald appears, it causes the bark to crack or discolour. There might be sunken areas in the trunk. This is problematic because the tree is now vulnerable to insect infestation and the cracks allow an entry point for disease.
Which Trees are Most Susceptible?
Thin-barked, young trees with southwest exposure are most vulnerable to sunscald. When trees grow, they develop a thicker bark which protects them. Fruit trees (such as peach, cherry, and plum) have thin, darker bark — even as they mature.
Trees that are well-hydrated as they enter the winter months are less vulnerable than trees stressed by drought. A professional tree service in Ontario can provide perforation (which adds water and soil to the root balls of trees to prepare them for winter). This will condition the soil and promote healthy feeder roots, making the trees less prone to sunscald.
Protecting Trees
Avoid over-pruning and removing lower limbs too early in the season. They provide protection to the trunks during the winter. It is a good rule of thumb to not remove the lower limbs until two or three years after planting.
One way to protect trees from sunscald is to wrap the lower branches and trunk with a light-coloured tree wrap during the winter season. Wraps can be purchased from home and garden stores, or applied by an experienced arborist. The wrap reflects light which keeps the bark cooler and encourages dormant bark cells to remain inactive. Trees will be at less risk when temperatures drop.
Wraps should be placed around the trees during late fall. The most prevalent time for sunscald is mid to late winter. Most of the damage occurs when the days become warmer but nights remain cold. When the risk of freezing has passed in spring, wraps should be removed. Leaving them on for the growing season can cause damage from the moisture they retain provide a place to harbour harmful insects.
What to do if Sunscald Occurs?
If your tree shows the symptoms of sunscald, first assess if the tree is worth saving. There is a possibility, if the damage is not too great, the tree may repair itself. If you decide to make the effort to try and save the tree, do not surround the damaged areas with wound dressing. This will interfere with the tree’s own natural process to heal. Contact the tree professionals at Dave Lund Tree Service & Forestry. We can help you assess the situation and decide what course of action to take to help heal your tree: 1-800-363-0511
Richmond Hill: 905-884-0511
Bradford:905-775-1020