SYMPOSIA PAPER Published: 01 January 1992

Some Factors Affecting Herbicidal Activity of Glyphosate in Relation to Adjuvants and Droplet Size


The influence of four adjuvants (Ethokem, Multifilm, Regulaid and Tween-20) and four spray-droplet sizes (159, 332, 447, 575 μm) on efficacy and crop tolerance with a glyphosate formulation were investigated for white birch [Betula papyrifera L.] and white spruce [Picea glauca (Moench) Voss] under greenhouse and laboratory conditions. It was found that some adjuvants (Ethokem, and Tween-20) enhanced the effectiveness of glyphosate sprays without damaging the crop (white spruce) species. Tests with 14C-glyphosate showed greater penetration and translocation by birch leaves when an adjuvant was used. Of the four droplet sizes tested, small droplets (159 μm) of glyphosate were more phytotoxic than large drops (575 μm). The implication of these findings in relation to herbicidal action of glyphosate on forestry species is discussed.

Author Information

Prasad, R
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Developed by Committee: E35
Pages: 247–257
DOI: 10.1520/STP16885S
ISBN-EB: 978-0-8031-5181-9
ISBN-13: 978-0-8031-1414-2