The old saying is if you don’t like the weather in Kentucky just wait a few hours. Last Sunday it was in the 80s, Wednesday morning it was 24 degrees (that was five feet above the ground) at sunrise here and that was after snow the day before!
Low temperatures will vary depending on elevation and other factors though. Statistically there’s a 10 percent chance of a hard freeze up to April 17 so what happened last week isn’t necessarily out of the ordinary. Plants had to endure single digit temps through the winter and now this hard freeze for some areas of the county.
So how will things fare? By now you could be seeing the results on some plants, others will show up later as warm days arrive.
Fruit tree damage
John Strang, University of Kentucky horticulture specialist, recommends checking page 65 of the Midwest Fruit Tree Spray Guide (ID-92) for critical temperature tables for various tree fruit floral stages. It can be found at http://www2.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/MwTreeFruitSprayGuideID92.pdf.
Floral hardiness varies with the weather that the flowers were exposed to during the previous several days before the freeze. Flowers tend to be less hardy when the temperature has been warm and they are growing rapidly, which was exactly what we had.
Strang explains that misting or sprinkling blooms early in the morning will not help. If it is below freezing, evaporative cooling as the water evaporates will drop the temperature even lower. The heat of fusion that is given off as the water freezes from wetting the plants once will be minimal and short lived.
The way that overhead sprinkling works is that when water is continually applied it continues to freeze and gives off its heat of fusion keeping the buds at about 29 degrees. This compensates for evaporative cooling heat loss if it isn’t too windy or excessively cold.
Covering trees with a plastic bag and tying it around the trunk does not improve frost protection because there is no source of heat to keep the flowers warm. On a frost night the natural heat source is long wave radiation released from the ground.
Strawberries, field crops
What about the strawberries you have out?
According to Strang, the critical temperatures are 30 degrees for open flowers and 28 degrees for small fruit. These plants could have been covered with a floating row cover. A 1.5 oz./square yard cover will provide about 4-6 degrees of protection. If possible plants should be covered with two row covers or with a frost cover (2.5 oz./sq. yard) next time.
So what about our field crops?
Most established cool season pasture grasses should be fine if they made it through the winter. If you have some that are still brown and haven’t greened up yet go out and grab a handful and see if they pull up easily. If they resist then you’re OK and they should green up still.
When temperatures go below the critical 24 degrees for extended periods, the terminal bud (growing point) of alfalfa and red clover has been killed. In other words, top growth is finished, and regrowth now will only come from crown buds at the base of the plant or axillary buds at the base of the stems.
The most significant damage occurs on new legume stands still in the two leaf stage. If this kills off your newly-seeded alfalfa you still have time to replant (up to May 1) without problems with alleopathy, or plant residue inhibiting new seed.
Carrie Knott, UK Extension agronomist, reported that most of the wheat crop in Kentucky is either still tillering (Feekes 4-5) or just beginning to joint (Feekes 6). Although this has presented management challenges this year, it also may have protected the crop against freeze injury from the unusually cold temperatures last week.
Significant wheat injury occurs when there are at least two hours of temperatures at or below 12 degrees for Feekes 1-5 (tillering) and 24 degrees for Feekes 6-7 (jointing) (check the table from page 17 of ID-125 for pictures, http://www2.ca.uky.edu/agc/pubs/id/id125/id125.pdf).
Agronomists use the Feekes scale to identify the growth and development stages of cereal crops.
Chad Lee, UK grain specialist, said polls indicate that central Kentucky wheat is around Feekes 4 or 5. Therefore, we should not be affected too severely by the cold and snow in central and eastern Kentucky.
Typical freeze injury for wheat that is Feekes 1-5 is leaf yellowing, burnt leaf tips, silage odor, and/or blue cast to fields. Characteristic injury from Feekes 6-7 is death of the growing point, leaf burning or yellowing, lesions, splitting, or bending of the lower stems and silage odor.
Although the temperatures indicate that wheat freeze injury is unlikely, it is important to scout fields to determine if freeze injury has occurred in small areas of fields. Freeze injury can be isolated to low areas of fields where cold air settles. It typically takes about 10 days of warm temperatures before injury can be seen. If you’re seeing damage to your agricultural crops let us know what you are seeing so we can report back to the specialists.
Scrap metal collection set
Look around your place for scrap metal that can be recycled and plan to bring it to Lakeview Park during Spring Scrap Metal Collection set for 8 a.m.-4:30 p.m. Monday through Saturday.
Items accepted include: metal, appliances, appliances with Freon, fencing, sheet metal, farm equipment — pretty much anything metal from the home or farm.
Items not accepted are: tires, oils, electronics and/or televisions.
For more information call 502-352-2701. franklincountyconservationdistrict.com.