Cold enough for you?

Last week was scary for fruit-bearing trees. My thermometer is in the chick brooder, so I do not know exactly how cold it got on Avery Branch but the weather app said 14 degrees at 8 a.m. Tuesday morning. University of Tennessee Fruit and Nut Specialist Dr. David Lockwood forwarded the information below on critical temperatures for different fruit buds and how to assess bud damage following a cold event. The first step in damage assessment is correctly identifying the bud stage. In apples, silver tip buds (the first stage) can tolerate temperatures down to 15 degrees with only 10% fruit loss. Temperatures down to 2 degrees result in 90% fruit loss. As buds swell, they become more sensitive to cold. If the mercury dips to 28 degrees during full bloom (the final stage), expect 10% fruit loss, if temperatures slide down to 25 degrees, prepare for 90% crop loss. It takes several hours before freeze damage symptoms develop. As frozen tissue thaws it turns black or brown. Pistils (the female part of the flower that becomes the fruit), rather than flower petals are the best indicator of freeze damage. If the pistil is brown or black it has been killed and will not form fruit. Check the center of each flower for the pistil – green is good, black is bad. Luckily, apple, pear, plum and even peach trees can produce a crop after a freeze event. Not all buds mature at the same time and later developing buds and flowers near the bottom of the tree often survive early cold snaps. Commercial orchardists exert considerable time thinning fruit, with an eye towards growing a moderate number of large healthy apples rather than lots of smaller ones, for instance. Mother nature may have done us a favor last week unless your small fruits, i.e., cherry and blueberry buds were damaged. A successful small fruit crop requires many individual berries or cherries and buds often mature in clusters within a tighter window than apple buds. The good news is most apple trees in Johnson County were in the silver to green tip stage, making them pretty resilient to cold temperatures. Our old pear tree was not so lucky and expect a complete loss of peaches. Bradford pears and their invasive cousin the callery pear were in full bloom and if we are lucky all of their blooms and pistils were damaged. Dr. Lockwood will be in town April 23 teaching a class on home strawberries at 1:30 p.m. The $5 registration fee ensures paid participants receive a limited number of bareroot plants. Stop by the UT/TSU Extension office to register by March 26.