2, 4-D Residues in tubers; Texture and respiration of potatoes in storage

Residues of 2, 4-D found in potato tubers ranged from 15 to 30 ppb at harvest when 2, 4-D was applied at the rate and time recommended for enhancement of color and control of tuber size. When used at higher rates and applied later, average residues reached 110 ppb. These residues did not include 2, 4-D bound to plant metabolites. In a single test, hydrolysis with aqueous acid resulted in a two to seven fold increase in 2, 4-D residues, suggesting a considerable portion of the 2, 4-D becomes combined with plant metabolites. Apparent respiration in storage of tubers from plants treated with 2, 4-D averaged 11% higher than tubers from plants not sprayed, but this was not great enough to be significant. Tubers of the same specific gravity from unsprayed plants and those sprayed with recommended rates of 2, 4-D were similar in texture.