Silwet M improves performance of glyphosate on gorse

Balneaves, J.M.; Fredric, B.J.

doi:10.30843/nzpp.1988.41.9881

Cited by 3 publications

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“…A plateau in herbicidal activity observed at 2 and 3 g/litre L-77, suggests a threshold concentration which must be exceeded before any additional effect is achieved. A similar threshold has been reported previously by Balneaves & Fredric (1988). Application of L-77 alone (2 g/litre) resulted in a significant reduction in the height of green stems and the death of one plant (Table 1).…”

Section: Resultssupporting

confidence: 88%

“…It is possible that high levels of the surfactant, through rapid stomatal entry, accounted for the phytotoxic effect of these treatments in the absence of glyphosate. Phytotoxicity of L-77 to gorse has been described previously (Balneaves & Fredric, 1988), although L-77 is regarded as less damaging to plant foliage than several other commonly-used nonionic surfactants (Neumann & Prinz, 1974;Coupland, Zabkiewicz & Ede, 1989).…”

Section: Resultsmentioning

confidence: 95%

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The effect of varying rates of glyphosate and an organosilicone surfactant on the control of gorse

Balneaves

Gaskin

Zabkiewicz

1993

Annals of Applied Biology

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The herbicidal effect of glyphosate applied to gorse (Ulex europaeus L.) was improved by the addition of increasing amounts (0.5-20 g/litre) of Silwet L-77, an organosilicone surfactant. Increasing the rate of herbicide also enhanced control. There was a highly significant interaction between surfactant rate and herbicide dosage; as the amount of Silwet L-77 was increased the rate of glyphosate could be reduced without loss of herbicide efficacy. However, without any added organosilicone surfactant, glyphosate did not provide more than 73% control of gorse at any rate up to 6.5 kg a.i./ha. With the addition of Silwet L-77, complete mortality of all plants could be achieved with 2.2 kg glyphosate/ ha. Neumann P M. Prinz R. 1974. Evaluation of surfactants for use in the spray treatment of iron chlorosis in citrus trees. Journal of Science. Food arid Agriciiltiire 25:221-226. Policello G A, Murphy G J. 1992. Influence of cosurfactants on spreading ability of organosilicone wetting agents. In Third Ititernutiotial Symposium on Adjiiuants f o r Agrochemicals (Abstract). UK: SCI Pesticides Group. Stevens P J G, Gaskin R E, Hong S 0. Zabkiewicz J A. 1991. Contributions of stomata1 infiltration and cuticular penetration to enhancements of foliar uptake by surfactants. Pesticide Science 33:371-3x2. Turner D J. 1985. Effects on glyphosate performance of formulation, additives and mixing with other herbicides. In The Herbicide Glvphosate. pp. 221-240. London: Butterworths. Wyrill J B, Burnside 0 C. 1977. Glyphosate toxicity to common milkweed and hemp dogbane as influenced by surfactants. Weed Science 25:275-287. Zabkiewicz J A, Gaskin R E. 1989. Effect of adjuvants on uptake and translocation of glyphosate in gorse (Ulex eiiropaeus L.). In Adjiiaants and Agrochetnicmls. Volirtne I ; Mode of Action arid Physiological Acriuity. pp. 111-150. Boca Raton: CRC Press. Zabkiewicz J A, Coupland D, Ede F. 1988. Effects of surfactants on droplet spreading and drying rates in relation to foliar uptake. In Pesticide Formulations, Innovations and Deuelopments, A C S S~tnposiutn Series 371. pp. 77-89. Washington DC: American Chemical Society. Zabkiewicz J A, Gaskin R E, Balneaves J M. 1985. Effect of additives on foliar wetting and uptake of glyphosate into gorse. Application and Biology. British Crop Protection Coiincil Monograph 28:127--133.

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 95%

The effect of varying rates of glyphosate and an organosilicone surfactant on the control of gorse

Balneaves

Gaskin

Zabkiewicz

1993

Annals of Applied Biology

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Contributions of stomatal infiltration and cuticular penetration to enhancements of foliar uptake by surfactants

et al. 1991

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Radiolabelled deoxyglucose (DOG) and glyphosate were used to investigate the effects of certain non‐ionic surfactants on the kinetics of foliar uptake in three species. ‘Silwet L‐77’ (5 g litre−1), an organosilicone surfactant, enabled spray solutions to infiltrate stomata, providing uptake of DOG into Vicia bean (50%), oat (35%) and wheat (20%) within 10 min of application. ‘Silwet Y‐12301’, another organosilicone, also induced stomatal infiltration but to a lesser extent; unlike L‐77, this was attenuated by partial stomatal closure. A third organosilicone, ‘Silwet L‐7607’, and two conventional surfactants, ‘Triton X‐45’ (OP5) and ‘Agral 90’ (NP9), did not induce stomatal infiltration. The effective minimum concentration of L‐77 required to enable infiltration of stomata was 2 g litre−1. The uptake of glyphosate into bean did not differ from that of DOG but the ‘Roundup’ formulation of glyphosate partially antagonised the infiltration provided by L‐77. Addition of surfactants did not increase the rate of cuticular penetration of DOG into bean but total uptake was increased, except by NP9, either via infiltration (L‐77 and Y‐12301) or by extending the period during which penetration occurred (L‐7607 and OP5). The surfactants had a variable effect on rates of penetration of DOG into wheat and oat. In general, foliar uptake followed an exponential timecourse which was largely complete within 6 h and only rarely approached 100% of the applied chemical. The stomatal infiltration provided by L‐77 caused an increase in translocation of DOG in bean.

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Antagonism of the foliar uptake of glyphosate into grasses by organosilicone surfactants. Part 2: Effects of surfactant structure and glycerol addition

Gaskin

Stevens

1993

Pestic. Sci.

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A systematic investigation into the effects of a range of organosilicone surfactants on the foliar uptake of radiolabelled glyphosate into wheat revealed significant antagonism associated with the chemical structure of these adjuvants. Rates of herbicide uptake were influenced by the ratio of the ethylene oxide (EO) hydrophile to siloxane hydrophobe, the mean EO chain length of the surfactant and the chemical nature of the terminal group on the EO chain. In general, antagonism was reduced, or even eliminated, by increasing the polarity of the organosilicone surfactant molecule. Typically, these surfactants markedly enhanced the initial rate of glyphosate uptake, which then slowed abruptly to reach a maximum within 4 h, in contrast to the approximately linear uptake response of the herbicide alone over 24 h following foliar application. The addition of glycerol further increased the initial rapid rate of glyphosate uptake in the presence of an organosilicone, but had no effect on the subsequent slowing down of foliar uptake. These findings are discussed in relation to the possible mechanisms by which these surfactants affect the cuticular penetration of glyphosate.

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Silwet M improves performance of glyphosate on gorse

Cited by 3 publications

References 0 publications

The effect of varying rates of glyphosate and an organosilicone surfactant on the control of gorse

The effect of varying rates of glyphosate and an organosilicone surfactant on the control of gorse

Contributions of stomatal infiltration and cuticular penetration to enhancements of foliar uptake by surfactants

Antagonism of the foliar uptake of glyphosate into grasses by organosilicone surfactants. Part 2: Effects of surfactant structure and glycerol addition

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