Tony Glover, Alabama Cooperative Extension System
Apple growers in north Alabama have suffered a severe setback this year in that they have basically lost the 2010 crop. Apple fruit began falling off the trees the weekend of May 7-9, 2010. Most varieties do not have any fruit left on the tree. This disaster is region-wide and apple growers from north Alabama to northern Virginia are seeing the same thing. This also includes north Georgia, Tennessee, and western North Carolina. Commercial orchards with high levels of management and home orchards and yard trees have been affected. A possible explanation came from Dr. Steve McArtney at the Mountain Crops Horticultural Research Station in Fletcher, N.C. After reviewing climate data for us from March 1 to present, Dr. McArtney says that it appears that unusually high nighttime temperatures on May 2 and 3 caused an increased respiration rate, and all the carbohydrates the trees made during the day were burned up during the night. When carbohydrates are in short supply, the tree tends to use what’s left for shoot growth at the expense of fruit growth. The application of chemical thinners, which is a normal procedure, made this particular fruit drop worse. However, even where thinners were not used, fruit set is extremely light in Alabama.