Frost cracks and winter sunscald: how to recognise and treat it

Growing conditions

Frost cracks and winter sunscald — Photo: Roger Griffith, Public domain, Wikimedia Commons

Symptoms

Long vertical splits in the trunk, usually on the south or south-west side.
Sunken, discoloured patches of bark on the sunny side of the trunk.
Damaged bark later cracks or falls off in patches, showing dead wood beneath.
Young trees and thin-barked fruit trees such as apple, pear, cherry and peach are most at risk.

Organic treatment

Do not paint or tar the crack; wound dressings get in the way of the tree's own healing.
Trim away only loose, dead bark.
A light-coloured tree wrap over the damaged trunk can help.

Chemical treatment

Reference information, not a guarantee. Read and follow the label of any product: dose, safety and the days to wait before harvest.

Prevention

Wrap young trunks with white tree wrap in autumn and remove it in spring once nights stay above freezing.
Or paint trunks with white interior latex paint, diluted 1:1 with water.
Protect newly planted trees for at least two or three winters.
Water trees well before winter and avoid mower and trimmer damage to the trunk.

Plants it affects

Sources

Figures checked against these sources.