Absorption and translocation of glyphosate with conventional and organosilicone adjuvants

Abstract

This study was conducted to determine the effects of three organosilicone-based and six conventional organic adjuvants on the absorption and translocation of 14 C-glyphosate in guineagrass and redroot pigweed.The organosilicone adjuvants produced rapid absorption of the 14 C-glyphosate into the redroot pigweed leaves, reaching maximum absorption within 0.5-1.0 h after application. The conventional adjuvants produced slower absorption of the 14 C-glyphosate, as the maximum absorption was not achieved until at least 24 h after application in redroot pigweed, remaining similar until 72 h. In guineagrass, the maximum absorption of the glyphosate was earlier than 24 h with the organosilicone-based adjuvants, compared with longer times for the conventional adjuvants. The organosilicone-based adjuvants also increased the glyphosate translocation in redroot pigweed, but not in guineagrass. Organosilicone adjuvants have the potential to provide greater rainfastness to glyphosate on redroot pigweed and, to a lesser extent, on guineagrass.

Potential for foliar phosphorus fertilisation of dryland cereal crops: a review

“…Adjuvants are capable of increasing retention time, lowering surface tension, adjusting pH and spreading foliar liquid over a larger leaf area compared with a foliar chemicals applied with no adjuvant (Fig. 1b) (Stein and Storey 1986;Stock and Holloway 1993;Wiesman et al 2002;Liu 2004;Singh and Singh 2008).…”

“…Silicone-based non-ionic surfactants are recommended due to their ability to reduce surface tension and the contact angle of the spray solution (Knoche 1994;Singh and Singh 2008). Glyphosate is an anionic foliar-applied herbicide, therefore, studies of foliarly applied glyphosate are particularly relevant to anionic foliar P applications.…”

“…Glyphosate is an anionic foliar-applied herbicide, therefore, studies of foliarly applied glyphosate are particularly relevant to anionic foliar P applications. Singh and Singh (2008) compared the translocation of 14 C-glyphosate combined with organosilicone (0.125% v/v) or conventional organic (0.5% v/v) adjuvants. Absorption of 14 Cglyphosate was greater when sprayed with organosilicone adjuvants than for conventional adjuvants on redroot pigweed leaves, reaching maximum absorption within 0.5-1.0 h after application.…”

Transport properties of the mung bean (Vigna radiata ) non-aerial hypocotyl membrane: permselectivity to hydrophilic compounds

“…trimesium, isopropylammonium, ammonium, sodium) exhibit high water solubility, but similar to imidacloprid, lipid solubility is extremely low . In the absence of adjuvants, the penetration of C‐glyphosate (isopropylammonium salt) 2 days after the application on guinea grass ( Panicum maximum ) and redroot pigweed ( Amaranthus retroflexus ) adaxial leaves showed an amount of 2.3 and 3.1% of the amount applied respectively . This indicates that even without the presence of adjuvants, imidacloprid as well as glyphosate molecules (although at extremely slow rates), are able to penetrate the aerial cuticular membrane (CM).…”

“…44 In the absence of adjuvants, the penetration of 14 C-glyphosate (isopropylammonium salt) 2 days after the application on guinea grass (Panicum maximum) and redroot pigweed (Amaranthus retroflexus) adaxial leaves showed an amount of 2.3 and 3.1% of the amount applied respectively. 25 This indicates that even without the presence of adjuvants, imidacloprid as well as glyphosate molecules (although at extremely slow rates), are able to penetrate the aerial cuticular membrane (CM). This suggests that pores of the same size as those found in the non-aerial hypocotyl exist as well in the aerial CM.…”