Absorption, Translocation, and Metabolism of 2,4-D and Glyphosate in Hemp Dogbane (Apocynum cannabinum)

Abstract

Low recoveries of total applied14C in translocation studies and erratic control of hemp dogbane (Apocynum cannabinumL.) in the field showed a need for a balance-sheet study of absorption, translocation, and metabolism of14C-2,4-D [(2,4-dichlorophenoxy) acetic acid] and14C-glyphosate [N-(phosphonomethyl)glycine]. Total recovery of14C-herbicides applied to hemp dogbane in the laboratory was 97% for 2,4-D and 105% for glyphosate. Of the14C recovered after 12 days in the hemp dogbane, 34 to 55% was parent-2,4-D after 2,4-D treatment, and 93 to 96% was parent glyphosate after glyphosate treatment. Only negligible amounts of14C were lost via volatilization or evolution as14CO2. A broadcast treatment with unlabeled herbicide did not significantly affect subsequent absorption, translocation, or metabolism of either herbicide. Total herbicide absorbed and translocated out of the treated area of the leaf generally increased during the subsequent 12 days for 2,4-D but only 3 days for glyphosate. A greater percentage of the total applied 2,4-D (31 vs. 14%) and glyphosate (14 vs. 8%) was translocated from upper rather than lower leaves of hemp dogbane, respectively. Higher temperatures (30 vs. 25 C) resulted in greater translocation of glyphosate (39 vs. 18%) but not 2,4-D (35 vs. 39%). Higher light intensities resulted in greater accumulations of 2,4-D into roots and of glyphosate into untreated areas of the treated leaf. Autoradiographs showed that both herbicides moved through hemp dogbane in a typical symplastic pattern and accumulated in roots and new leaves.

Metabolism of 2,4‐dichlorophenoxyacetic acid contributes to resistance in a common waterhemp (Amaranthus tuberculatus) population

“…The model of 2,4‐D metabolism over time showed that resistant plants metabolized 2,4‐D seven times faster than did susceptible plants. Previously, 2,4‐D‐susceptible hemp dogbane ( Apocynum cannabinum ) was found to metabolize only 48% of the herbicide at 12 days after application . Euphorbia esula plants susceptible to 2,4‐D contained 85% of the parent [ 14 C] 2,4‐D at 72 HAT .…”

Glyphosate and phosphorus leaching and residues in boreal sandy soil

“…Sprankle et al (1975a) found that after foliage application, the total translocation to rhizomes and shoots was 66.7% of foliage-absorbed glyphosate, accounting for 35% of the total amount of applied glyphosate. According to Schultz and Burnside (1980) and Alister et al (2004), 52% and 22% of foliage-absorbed glyphosate, respectively, were found in roots. Moreover, Arnaud et al (1998) reported that about 22% of applied glyphosate was recovered in roots.…”

2,4-D Past, Present, and Future: A Review

“…Limited research has been conducted regarding the effect of light on 2,4-D uptake and translocation. Uptake of 2,4-D is consistently increased in the presence of light as compared with dark, but the effect of light intensity appears to vary by species (Sargent and Blackman 1972;Schultz and Burnside 1980). However, light intensity may influence translocation as demonstrated by Schultz and Burnside (1980) in hemp dogbane (Apocynum cannabinum L.), where increasing light intensity from 50 to 75 flux resulted in 14% greater movement out of the treated leaf.…”