Fruit drop just before harvest is a serious problem for some apple varieties grown in New York, according to Dr. Terence Robinson and Steve Hoying of Cornell University, New York.
Many commercial apple growers with sensitive varieties lose 5 to 25 percent of their apple crop due to preharvest fruit drop, which occurs just before fruit develop optimum red color, maturity, and size, the horticulturists write in a publication about the use of stop drops.
They list these four reasons why applying a stop-drop material is important:
—First, to keep apples on the tree until they reach physiological maturity. McIntosh, Macoun, and Honeycrisp drop before they are physiologically mature. Apples picked before maturity are small, undercolored, starchy, have a poor taste without varietal flavor or sweetness, and do not store well.
—Second, to allow apples extra time on the tree to increase fruit size and yield and to obtain marketable color. Some varieties such as McIntosh will drop as they wait for color. Since environmental conditions with warm days combined with cooler nights trigger color development, applying stop drops will delay harvest, sometimes pushing apples into windows of improved weather for coloring. Fruit size and total yield also increase since apple size continues to increase.
—Third, to hold apples on the tree for an extended period of time so that they will be available for extended harvest, as in you-pick situations.
“You-pick operations rely on the public to harvest the fruit,” Robinson and Hoying wrote in a paper on the subject. “Often the success of these operations depends on having a wide variety of fruit available for picking at any one time.
Most consumers do not realize that the optimum picking window is relatively short, and the less experienced expect their favorite variety to be available throughout the fall. Growers try to accommodate these consumers by having the widest variety of fruit available through the harvest window by using a number of tactics. Delaying maturity and preventing fruit drop are two of these strategies.”
—Fourth, to manage the harvest season when there are too many apples to harvest during the time window available with the labor available. A grower can, by applying ReTain at different times to different blocks, extend the harvest season for a single variety for either labor supply or marketing reasons.
Perhaps a fifth reason is the low value of dropped apples. Not only have sweet cider prices been pushed down by imported apple juice concentrate, but salvaging of dropped apples for juice is being discouraged in several states. While pasteurization eliminates the risk, marketers are increasingly concerned about the apple image and consider any risk too much risk.
Dropped apples left in orchards, on the other hand, produce objectionable odors, attract wasps, and in other ways make harvesting difficult for hired workers and for you-pick customers. • —R. Lehnert
Related Story: How to retain the crop