LEXINGTON, Ky. — Heat units necessary for fruit crop development have accumulated very rapidly as reported in last month’s Fruit Facts and our fruit crops continue to develop well ahead of schedule. Figure 1 shows Lexington heat unit accumulations expressed as Growing Degree Days for 2017 in comparison with a number of previous years. As of March 27, plant development is running about a month earlier than normal.
The week of freezing weather ending the morning of March 16 caused freeze damage on a few of our fruit crops. Figure 2 shows the Kentucky NWS lowest temperatures experienced between March 15 and 17. Some sites at lower elevations were somewhat colder than those shown here. Peach flower injury appeared to be less than what would be expected based on the charts found in the “Disease and Insect Control Programs for Homegrown Fruit in Kentucky (ID-21)” publication at http://www2.ca.uky.edu/agcomm/pubs/id/id21/id21.pdf Keep in mind that peaches only need about 10% of their flowers to survive to produce a full crop. Injury to peach buds and flowers was quite variable across the state. At the UKREC in Princeton ‘Redhaven’ peach had 36% live flowers and at the Horticulture Research Farm in Lexington an older ‘Madison’ tree which was in pink had 82% live buds, while the ‘Coralstar’ tree in my backyard located in a frost pocket did not have any live buds. Growers in Owensboro and Bowling Green report that they still have full crops of peaches, while those in Somerset and Paris report freeze outs on peaches. Peach buds in the northern portion of Kentucky were still mostly in the pink stage and avoided injury.
Matted row strawberry growers should be fine as the flower buds were not visible in the crowns at the time of the freezes. However many plasticulture strawberry growers had plants in bloom. Growers that covered plants with 2-3 floating row cover layers and in some cases ran drip irrigation beneath the row covers, covered plants with straw and then pulled the row covers over the plants are finding live flower buds. It is still a little too early to evaluate flower survival because, many flowers are very small and down in the crowns.
Highbush blueberry growers that have varieties with expanding flower buds may find a very few damaged flowers, but most should not find any damage. Southern highbush blueberry growers that are growing varieties such as Oneal and Star that have expanded flower buds have lost the crop in the southern part of the state.
Grape growers are seeing little or no injury. Plants that are in a weakened condition, particularly young plants or those infected with crown gall may have pushed buds a little early and could have some injury.
Apples, pears, tart cherries, blackberries and raspberries are not showing any damage.
— John Strang, U.K. Extension Horticulturist, Matt Dixon and Tom Priddy, U.K. Ag Meteorologists, Kentucky Fruit Facts
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