Monday, April 29, 2013

Spring 2013: Recent Cold Causes Some Plant Damage by Mary Small

Last week the weather looked and felt more like winter than spring and the cold temperatures have many wondering how it affected or will affect trees and shrubs.
We found freeze injury (dead flower buds and a few tiny dead leaves) on ornamental pears and some crab apples at the Jefferson County fairgrounds. Plant damage on your property will depend upon where they are located in the landscape, how low temperatures were for how long and plant developmental stage.

Photo by Mary Small
You can check your plants for freeze injury by first examining flower leaf buds. If they are brown and crispy, they are dead.  The tree or shrub will not produce more this year. You can break off a couple leaf buds and look for green interiors to tell you they are still alive. Crispy brown leaves should be replaced by new ones as the season progresses. If there is stem or twig damage, it may not appear until a bit later in the season.  Look for branch/twig buds that don’t open, typically from the branch tips inward toward the trunk. Sometimes buds will open but fail to grow or grow only a short time because tissues supplying water needs were damaged or destroyed, too.

I don’t expect to see much root damage since wet soil and snow cover provided good insulation for them.
Fortunately most woody plants have great resiliency.  If primary buds were killed, secondary buds will grow and form new stems and leaves. This is the same mechanism that occurs when you prune off a branch and new ones form below the cut.
Trees and shrubs that were struggling going into fall and winter have the greatest chance of injury.  For most plants, the greatest injury may be a loss of overall vigor, but that will be hard to determine until they “get growing”.  Give plants time to develop before making pruning or removal decisions this year.

Photo by Mary Small