Epicuticular wax is a major barrier to the movement of foliar-applied herbicides into plant leaves. Many researchers have evaluated the penetration of herbicides in plants using similar methods. However, the methods used to remove unabsorbed herbicide from the leaf surface have been inconsistent among scientists. Laboratory experiments were conducted to evaluate the effectiveness of various compounds as a leaf wash for removing unabsorbed ¹⁴C-labeled herbicides from shattercane and velvetleaf leaves. Product B and Product C provided poor results as a leaf wash compared with water, chloroform, methanol, and Product A. Product A increased the amount of ¹⁴C-bentazon removed from velvetleaf by 26% compared with the amount removed by chloroform, methanol, or water. Removal of ¹⁴C-nicosulfuron was not different between chloroform, Product A, methanol, or water. Although water was the best treatment for the two salts of ¹⁴C-glyphosate, Product A was as good or better than chloroform and methanol.

Nomenclature: Bentazon; glyphosate; nicosulfuron; shattercane, Sorghum bicolor L. #³ SORBI; velvetleaf, Abutilon theophrasti L. # ABUTH.

Additional index words: Epicuticular wax, leaf wash, radiolabeled herbicides.

Abbreviations: IPA, isopropylamine; LSS, liquid scintillation spectrometry; TMS, trimethylsulfonium.