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April 20, 2007 "The late spring freeze severely damaged many native trees including the oaks, tulip poplars, and hickories."

At the UT Arboretum we have started documenting the effects of "the freeze" on a variety of plant species. We observed that many of our native trees were severely affected (tulip poplar, oaks, hickories), while others went relatively un-harmed (blackcherry, sugar maple, and sweetgum). The science and academic side of this event will be a feature of the UT Arboretum's web site (http://forestry.tennessee.edu) as we track the consequences of this unusual event.

For homeowners, this event is less academic and more a concern for what can be done to help our favorite landscape plants.

Mark A. Halcomb, University of Tennessee Area Nursery Specialist, Warren County Extension in McMinnville, TN advises in his "Nursery Notes" to "be patient and wait":

"The best advice is to wait; wait for the plants to respond. And do not fertilize.

Our plants were too far advanced for this time of year and were not in a physiological state to tolerate the freezing temperatures we received. The duration of the low temperatures over three nights coupled with 20 to 25 mph winds delivered damage that we could not provide adequate protection for. No one remembers this sort of thing.

As expected, it appears seedlings and first year buds have taken a major hit. It is too early to determine if there will be twig dieback or how much. Seed crops may be damaged on the trees, such as redbud, tulip poplar, maple and dogwood.

Dieback will vary with the plant genus, elevation, stage of growth, etc. Warmer temperatures will allow dieback to become more evident. A caramel or light brown color under the bark will indicate cold injury and the tissue will be weak or possibly die. If discolored, wait 2 more weeks and check again. It may get more obvious that the plants will not recover.

There is no way of knowing yet how much terminal dieback there will be on field or landscape plants. Wait until new growth begins again and make the cuts into 100% live and healthy tissue. It is important the cut be made below any brown-colored tissue in the stem.

As plants attempt to re-flush new foliage, they will have to draw upon already depleted starch reserves. Any additional stress during this growing season - drought, insects, diseases, and even fertilizer - could cause trees to be weakened further or possibly die in some situations. Some trees, such as poplar and gum, will push out new foliage more quickly than oak.

Do not fertilize a stressed plant. Fertilizer will only add to the stress. The salt content in fertilizer (measured in EC electrical conductivity) adds another stress to a weakened plant.

It may be July before the verdict will be in on some plants."

(Updated 04/26/2007)

Return to "The Spring Freeze: Impact of the Drought"