Critical cold temperatures impact fruit crops

Apple, peach and strawberry growers reported early morning temperatures at damaging levels in the Rochester region on May 13. The lowest temperature reported was 26 degrees, while several other growers reported a low temperature of 28 degrees. Cold damage is expected but will largely depend on the stage of bud and/or blossom that the fruit tree or small fruit plant was in at the time it was exposed, according to Bob King, Cornell Cooperative Extension.

Cold damage is expected to be varied due to site location, air, drainage and the elevation. Early blooming varieties of apples and small fruits are the most likely to have been impacted since they were at the most advanced stages of bloom during the cold snap. Later season varieties of apples and small fruits were not as advanced in bloom and are expected to be in better condition. Cold damage is evident by flower tissue that has turned brown and water soaked. In addition, stems tend to be short, flower petals are misshapen and flowers per cluster are less than normal. Flowers such as these make for poor fruit quality when they are pollinated and set fruit.

Most farmers and growers think of frost as an indicator as to whether a critical cold temperature may been achieved, King said. Typically, frost occurs at 32 degrees and below with little or no wind movement. However, from 32 to 29 degrees frost is occurring at a slightly higher temperature but has not achieved a critical cold temperature of 28 degrees which will damage many types of tree and small fruit blossoms. Generally, if frost occurs above a critical cold temperature of 28, damage to a fruit tree or small fruit crop is minimal.