By LAURIE STEPANEK
NFS Forest Health Specialist
When freeze warnings are posted, gardeners carefully cover susceptible garden vegetables and flowers with blankets, sheets, buckets, and garbage cans. But larger shrubs and trees must fend for themselves. The freeze this past weekend left many woody plants across the panhandle with brown, drooping leaves and shoots.
“The first few weeks of May were unusually warm, which pushed a lot of new growth on our trees,” said Chrissy Land, Western Community Forester with the Nebraska Forest Service. “This new growth is very susceptible to freeze. I noticed damage on a wide range of trees: oak, ginkgo, Kentucky coffeetree, honeylocust, catalpa, redbud, and ash.”
Symptoms of freeze damage include curled, drooped, or shriveled leaves, shoots, and flowers. Affected tissues turn brown or black. Killed tissues eventually drop off, but new shoots usually grow from dormant buds.
Trees most noticeably affected are those with new succulent growth, however, trees that have not yet budded can also be affected by a late freeze. Poor leaf out on these trees may occur if buds are killed. Leaves that do emerge may have numerous holes—a condition known as leaf tatter.
Freeze damage may also trigger the development of latent fungal infections, resulting in twig or branch death later in the season.
Guidelines for managing freeze-damaged trees include basic tree care including pruning out dead branches and mulching with wood chips or another organic mulch to help improve the root environment.
“In the hot climate and sandy soils typical of the panhandle, apply two inches of water per week over a large area around the tree if it does not rain,” recommended Land. “However, do not fertilize unless there is a known nutrient deficiency.”
“Trees receiving good care will better handle the stress of an untimely freeze than those in poor health,” said Land.