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Effects of Plant Growth Stage on Glyphosate Absorption and Transport in Ligustrum (Ligustrum japonicum) and Blue Pacific Juniper (Juniperus conferta)
Published online by Cambridge University Press: 12 June 2017
Abstract
Carbon-14-labeled glyphosate [N-(phosphonomethyl)glycine] was foliarly applied to ligustrum (Ligustrum japonicum Thunb.) and blue pacific juniper (Juniperus conferta Parl. ‘Blue Pacific’) at the following growth stages: cold acclimation, winter dormancy, budbreak, shoot elongation, and termination of the first flush of growth (shoot termination). At shoot elongation juniper plants absorbed 2% of applied 14C by 14 days after treatment (DAT). Applications at other growth stages resulted in no significant absorption of 14C by junipers. Within 7 DAT the amounts of radioactivity absorbed by ligustrum were significant and depended upon growth stage in the following order: budbreak < shoot termination < shoot elongation. Absorption by overwintered leaves occurred at budbreak but not at elongation or termination. Transport of absorbed 14C in ligustrum was primarily acropetal and occurred only in budbreak and flowering treatments. Differences in tolerance to glyphosate between juniper and ligustrum appear to be related to differential absorption. Seasonal differences in ligustrum tolerance also appear to be associated with differences in absorption. Although growth stage affected transport in ligustrum, differential transport does not appear to play a major role in seasonal influences on long-term glyphosate phytotoxicity.
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- Weed Control and Herbicide Technology
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- Copyright © 1986 by the Weed Science Society of America
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