How to Protect Fruit Trees from Winter Damage: Sunscald, Rabbits and Mice
Cold itself is rarely what kills a hardy fruit tree on the Prairies. More often it is the winter sun, hungry rabbits and mice, or late-season growth that never hardened off. The good news is that most winter damage is easy to prevent if you set up protection in the fall.
The short answer
- Put spiral tree guards on young trunks every fall to stop sunscald, rabbits and mice. Remove them in spring.
- Or paint the lower trunk with diluted white latex paint to reflect winter sun.
- Do not fertilize with nitrogen in late summer or fall.
- Keep grass and mulch a little away from the trunk, and water well before freeze-up.
Based on the University of Saskatchewan apple growing guide.
Sunscald
On a bright February day, the sun heats the south and west side of a young trunk well above air temperature. The bark thaws, then refreezes at sunset, and the tissue underneath dies. The result is a long, sunken crack or dead patch on the sunny side of the trunk, often found in spring.
Prevention: install a spiral snow guard around the lower trunk in fall, or paint it with white latex paint diluted with water. Either reflects the sun and keeps bark temperature steadier. Young, thin-barked trees need it most.
Rabbits
Rabbits chew bark and small branches, usually from about 0.5 m above the snow line. As snow piles up, they reach higher. If they chew all the way around the trunk (girdling), the tree can die.
Prevention: spiral guards or wire mesh cylinders tall enough to stay above the deepest snow you expect. Install them before damage starts, not after.
Mice and voles
Mice tunnel under the snow and chew bark at the very base of the trunk, where you cannot see it until spring. Damage is usually low, near the ground.
Prevention: guards that reach down to the soil, and keeping grass, weeds and thick mulch at least a short distance from the trunk so mice have nowhere to hide right against it. USask recommends keeping grass and weeds about 1 m back from young trees.
Late growth that does not harden off
Fertilizer, especially nitrogen, applied in late summer pushes soft new growth that has no time to toughen up before winter, and it dies back. USask advises avoiding late-summer or early-fall nitrogen. If you feed, do it once in early spring, and an annual layer of compost is usually enough.
Dry winter injury
Evergreens and young trees can dry out over winter when the ground is frozen and wind keeps pulling moisture from branches. Water deeply in fall before the ground freezes, especially after a dry summer. Wind screens of burlap help young evergreens in exposed sites.
Snow load and breakage
Heavy, wet snow can split branches. Gently brush snow off young trees after a storm, and prune to strong, wide branch angles while trees are young; narrow forks split more easily.
A fall checklist
- Stop fertilizing by midsummer.
- Water deeply before freeze-up if the fall is dry.
- Install spiral guards or mesh on young trunks, or paint them white.
- Pull grass and mulch back from the base of the trunk.
- In the far north, consider wrapping trees or growing them as multi-stemmed shrubs, as USask suggests.
- Remove spiral guards in spring so they do not trap moisture or constrict growth.
Keep reading
Frequently Asked Questions
What is sunscald on trees?
Winter sun heats the bark on the south and west side of a young trunk, which thaws and refreezes and the tissue underneath dies. It shows up as cracked or sunken bark.
How do I stop rabbits eating my fruit trees?
Install spiral guards or wire mesh cylinders in fall, tall enough to stay above the deepest snow you expect.
Should I fertilize fruit trees in the fall?
No. Late nitrogen causes soft growth that is killed over winter. Feed once in early spring, if at all.
When should tree guards be removed?
Remove spiral guards in spring, after the snow melts, so they do not trap moisture or restrict growth.