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. 2020 Mar 1;9(3):297.
doi: 10.3390/plants9030297.

Effect of Adjuvant on Glyphosate Effectiveness, Retention, Absorption and Translocation in Lolium rigidum and Conyza canadensis

Candelario Palma-Bautista  1 , Jose G Vazquez-Garcia  1 , Ilias Travlos  2 , Alexandros Tataridas  2 , Panagiotis Kanatas  3 , José A Domínguez-Valenzuela  4 , Rafael De Prado  1
Affiliations

Effect of Adjuvant on Glyphosate Effectiveness, Retention, Absorption and Translocation in Lolium rigidum and Conyza canadensis

Candelario Palma-Bautista et al. Plants (Basel). .

Abstract

Glyphosate retention, absorption and translocation with and without adjuvant were examined in Lolium rigidum and Conyza canadensis in greenhouse and laboratory settings to develop an understanding of the influence of the selected adjuvant on glyphosate activity. Tests on whole plants show that the dose of herbicide needed to reduce dry weight by 50% (GR50) or plant survival (LD50) decreases by mixing glyphosate and adjuvant to 22%-24% and 42%-44% for both populations of L. rigidum and C. canadensis, respectively. This improvement in efficacy could be attributed to the higher herbicide retention and lower contact angle of the glyphosate + adjuvant drops on the leaf surface compared to the glyphosate solution alone. Plants of both species treated with 14C-glyphosate + adjuvant absorbed more glyphosate compared to non-adjuvant addition. Furthermore, the movement of the herbicide through the plant was faster and greater with the adjuvant. Our results reveal that the use of adjuvants improves the effectiveness of glyphosate in two of the most important weeds in agricultural crops in Mediterranean countries.

Keywords: absorption and translocation; efficacy; horseweed; retention; rigid ryegrass.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Glyphosate dose response in dry weight reduction and survival expressed as a percentage of the mean untreated control of C. canadensis (A and B) and L. rigidum (C and D).
Figure 2
Figure 2
Absorption of 14C-glyphosate from 12 to 96 h after treatment (HAT) in C. canadensis (A) and L. rigidum (B) populations. The vertical bars represent the standard error of the mean (n = 5).
Figure 3
Figure 3
Digital image (plants on the left) and autoradiography (plants on the right) show the distribution of 14C-glyphosate (A and C) and 14C-glyphosate + Adj (B and D) within C. canadensis and L. rigidum populations, at 96 HAT.
See this image and copyright information in PMC

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