The Use of 2-Chloroethylphosphonic Acid and Succinamic Acid 2,2-Dimethyl Hydrazide to Aid in Mechanical Shaking of Sour Cherries1

Both 2-chloroethylphosphonic acid (Ethrel) and succinamic acid 2,2-dimethyl hydrazide (Alar) aided machine harvesting and improved quality of mechanically harvested sour cherries, Prunus cerasus L., cv. ‘Montmorency’ in a two year experiment. Alar applied two weeks after bloom at 2000 ppm reduced fruit acid levels, reduced the force required for fruit removal, and advanced red color development, but when used alone did not reduce fruit removal force enough to make shake and catch harvesting economic. Ethrel at 500 ppm applied one week prior to harvest on trees previously treated with Alar (2000 ppm) proved to be the best treatment each season on trees tested in both years. This combination resulted in adequate fruit removal coupled with better fruit quality than was attainable with Ethrel alone. Ethrel at 250 or 500 ppm specifically and effectively enhanced fruit removal but was phytotoxic at 1000 ppm as evidenced by gumming and leaf removal.