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Commercial Horticulture > Comm Hort Blog > Posts > ​3rd Warmest Winter in Over 57 Years: Low Chill Hour Accumulation Concerns Fruit Growers

Only 485 hours below 45 degrees at CREC, Thorsby as of 1/15/16

The warmest fall in recent history has fruit growers and researchers paying close attention to weather forecasts in early 2016. Many fruit crops require a specific amount of dormancy or “rest” that occurs with the cold temperatures of winter, allowing them to bloom, fruit and grow normally when temperatures rise in the spring. Fruits grown in Alabama vary greatly in their chilling requirements. Fruits with high chill requirements including some cultivars of peaches, nectarines, plums, apples and cherries may have delayed blooming and reduced fruit size and yield if chilling is inadequate.

For this reason researchers and growers monitor winter chilling to better understand and predict crop performance and management needs of various crops. Temperatures between 32  and 55 degrees F are considered ideal chilling. For many years all hours below 45 degrees F between October 1 and February 15 have been recorded as a standard method of logging “chill hour” accumulation for each given year, while providing valuable data for comparison between crop years. On January 1, 2016, we had logged only 253 hours below 45 degrees F at the Chilton Research and Extension Center in Thorsby, marking the lowest Jan. 1 winter chilling accumulation on record since the Chilton Area Horticulture Substation staff began logging chill hours in the fall of 1956, some 57 years ago.

Thankfully, since the first week in January colder temperatures are bringing a much needed increase in chill hour accumulation. Even so, this winter is currently the third warmest on record in the past 57 years.

The 253 hours logged by January 1, 2016, compares to the 57 year average of 586 hours, or 481 hours averaged by Jan. 1 during the past ten years. The next lowest Jan. 1 chilling accumulation recorded occurred in 2007, which resulted in the fourth warmest winter on the 57 year record with 846 total chill hours by Feb. 15.

In the past 57 years, the four warmest years on record, logging under 360 hours by Jan. 1, averaged a total winter chilling accumulation of 730 hours by Feb. 15, compared to the 57 year average of 1190 hours, and the past 10 year average of 1012 hours logged under 45 degrees by Feb. 15.

Current research related to breaking dormancy and  materials labeled to provide some chilling replacement in fruit crops will be discussed at the Chilton Area Peach Production Meeting in Clanton on January 25. To register for the meeting please call the Chilton County Extension Office at (205) 280-6268.

Chill hour accumulations for the Southeast can be viewed online at

http://agroclimate.org/tools/Chill-Monitoring/, as well as a wide variety of crop weather related forecasts and tools helpful to growers and the agriculture industry.​


 

Gary Gray

ACES, Regional Ext. Agent


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