Daminozide and Unsymmetrical Dimethylhydrazine(UDMH) Residues in Fresh and Processed ‘Red Delicious’ Apples

Abstract

Daminozide is a growth regulating substance widely used on apples and other fruit crops to affect various fruit and tree characteristics. Daminozide residues were determined in ‘Starkrimson’ Red Delicious apples orchard-sprayed at both recommended and excessive rates, at recommended periods before expected harvest, and at several application times closer to harvest than recommended. Analyses were conducted on the whole raw fruit, including the peeling, and on applesauce processed from the peeled and cored fruit, immediately after harvest, and after cold storage periods of 30, 60 and 90 d. Residues in both the fresh and processed fruit were directly proportional to the concentration of daminozide in the foliar sprays, regardless of application date. The highest residues in both fresh and processed apples were in fruit from trees sprayed 14 to 28 d before harvest at all spray concentrations. Residues from all spray concentrations and all application dates were persistent for 90 d at 0°C storage for fresh fruit and at 23°C storage for processed fruit. Only the residues in fruit sprayed with four times the recommended level at 2 or 4 wk before harvest exceeded the U.S. Environmental Protection Agency tolerance level (30 ppm). Residues ranged from <2 to 32 ppm. Unsymmetrical dimethylhydrazine (UDMH) levels were directly proportional to the daminozide residues in the applesauce. Average UDMH residues ranged from 0.03 ppm for fruit sprayed with the recommended rate of daminozide to 0.8 ppm for fruit with the highest daminozide residues.