Extension > Garden > Yard and Garden > Fruit > Integrated pest management for home stone fruit growers > Winter injury
Winter injury in the wood of an apple tree. The bark is green but the wood is dark. The tree died in July
Thaddeus McCamant, Central Lakes College
Winter injury limits the distribution of many types of stone fruits in Minnesota. Peaches, sweet cherries and Japanese plums cannot be reliably grown in most parts of the state due to our severe winters. Varieties rated for zones 3 or 4 can have winter injury after severe winters or if the trees are stressed or diseased.
Occasionally, whole trees die after cold winters. In some cases, the trees will leaf out in the spring and die after the temperature warms. Branches of fruit trees that die from winter injury may have dark wood below green bark.
Winter injury can be minimized with proper tree care. Both cherry leaf spot and brown rot can dramatically increase the chance of winter injury. Cherry leaf spot can cause all the leaves on a tree to fall off by August or early September, making the trees vulnerable to winter injury. If new leaves start forming in September after the old leaves have fallen off, that branch will almost always die. Brown rot can cause twig blight which then weakens the tree, leaving the tree vulnerable to winter injury.
Always make sure the trees have sufficient water in late fall. Avoid pruning living wood after July 1, because pruning can delay dormancy. Plant varieties that have been shown to survive Minnesota winters. Characteristics of Minnesota hardy stone fruit varieties can be found in the publication Stone Fruits for Minnesota Gardens.