My mother is a member of South Kentucky RECC. She has a flowering crabapple tree that is splitting and peeling (see photo). She is wondering what causes this and if there’s anything she can do to prevent further damage.
The Gardener’s Answer
Thin-skinned trees like your mom’s crabapple (Malus spp.) are, in general, more prone to splitting and cracking. Environmental factors, such as fluctuating temperatures, combined with southern sun exposure during the winter months can cause freezing and thawing within the tissue. This tissue eventually dies, exposing the inner layers and making the branch less structurally sound and more susceptible to insect and disease issues.
The most common problems associated with crabapples in Kentucky are apple scab, fire blight, and/or cedar apple rust. From the photos that you sent, apple scab may be the concern. Some varieties of crabapple are more disease resistant than others, but like all other plants, if they are not given ideal growing conditions and properly pruned for structural durability, they are more susceptible to insect and disease issues.
Avoiding fertilizing too late in the season promotes growth, but it’s too tender to be exposed to freezing temperatures. I would recommend having a certified arborist come out and give your mom recommendations in terms of pruning and treatment options. The Somerset horticulture extension agent may be able to give you local recommendations for a certified arborist. The office can be reached at (606) 679-6361.