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To develop a practice to prevent preharvest drop in ´Tsugaru´ apples, aminoethoxyvinylglycine (AVG) was applied. from 1994 to 1995. Rate of preharvest drop associated with spray time and concentration of AVG was investigated and the additive effects of dichlorprop in AVG were also studied. It was clearly found that spray time of AVG affected more profoundly the preharvest drop than AVG concentration. Thus, preharvest drop was more effectively inhibited when AVG was sprayed 2 weeks prior to the estimated harvest time than l week. Also, the combined application of AVG with dichlorprop was more effective on prevention of fruit drop. Single application of AVG at 100 ㎎·L^(-1) resulted in the significant suppression of fruit color development. However, dichloprop (30 ㎎·L^(-1)) added in AVG partially enhanced the skin color development and rapid softening of flesh, which is common in dichlorprop-treated fruits, was overcome in part. Results indicated that the combined spray of AVG and dichlorprop will be an effective method to prevent preharvest drop in ´Tsugaru´ apples. Also, this had an advantage to complement the adverse effects induced by each chemical such as early softening by dichlorprop and poor fruit coloration by AVG.
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