Contact phytotoxicity of triclopyr formulations on three plant species in relation to their uptake and translocation

Forster, W. A.; Zabkiewicz, J. A.; Murray, R. J.; Zedaker, Shepard M.

doi:10.30843/nzpp.1997.50.11361

Cited by 6 publications

(3 citation statements)

References 7 publications

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“…Although it was not statistically compared, we also observed some variation in the nontarget species response to these triclopyr concentrations. Existing literature supports variation in interspecies susceptibility to triclopyr and, to a lesser degree, variation in intraspecies susceptibility to differing triclopyr formulations (de Mendiburu 2021; Forster et al 1997;Hutchinson and Langeland 2010;Kochenderfer 1999;Self 2020).…”

Section: Flooding Studymentioning

confidence: 99%

Physical and physiological pathways of off-target triclopyr movement and associated non-target injury following basal bark application

Oberweger,

Enloe,

Wilson

et al. 2023

Weed Sci

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Basal bark treatment with triclopyr butoxyethyl ester is used to control woody invasive plants, including Brazilian peppertree (Schinus terebinthifolia Raddi). However, the ester formulation cannot be applied where standing water is present, which includes wetlands where S. terebinthifolia is found. In 2009, a low-volatile acid formulation of triclopyr was labeled for use in aquatic sites, which allows for basal bark applications when standing water is present. This formulation may have utility for controlling woody plants in standing water. However, anecdotal observations of injury to non-target plants following applications during periods of inundation have been reported. To address this, mesocosm studies were conducted to assess non-target injury through triclopyr root exudation or release from the surface of treated stems via flooding. Mesocosms contained S. terebinthifolia as the treated target, while sugarberry (Celtis laevigata Willd.), buttonbush (Cephalanthus occidentalis L.), and red maple (Acer rubrum L.) were included as non-targets. In the first study, the pathway of root exudation for non-target injury following triclopyr (34 g L−1) basal bark application was isolated with activated charcoal placed at the soil surface. In the second study, mesocosms were flooded to assess triclopyr release from the surface of treated stems and subsequent non-target injury. Defoliation of non-target species posttreatment was ≤8%, and triclopyr was detected at ≤5 µg L−1 in mesocosm wells when activated charcoal was present. Posttreatment non-target defoliation up to 92%, coupled with triclopyr concentrations in surface waters and wells as high as 4,637 µg L−1, indicated triclopyr movement as a result of flooding. Additionally, triclopyr non-target injury from soil activity independent of flooding was observed. These findings provide limited evidence of triclopyr root exudation but considerable evidence of triclopyr release during flooding following basal bark treatment and support a cautionary approach to basal bark application when standing water is present.

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Section: Flooding Studymentioning

confidence: 99%

Physical and physiological pathways of off-target triclopyr movement and associated non-target injury following basal bark application

Oberweger,

Enloe,

Wilson

et al. 2023

Weed Sci

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“…It was recognized early on that translocation could be affected by contact phytotoxicity. In this situation, either the amount or rate of uptake of the herbicide spray formulants is so great that it results in localized leaf cell death with the consequent inability of the herbicide to move out of this zone ( Brian, 1972; Merritt, 1982; Knoche et al ., 1992 ; Forster et al ., 1997 ). Phytotoxicity has been related to surfactant structure (ionic surfactants being more phytotoxic) and EO content (low EOs being more phytotoxic than higher EOs).…”

Section: Formulation Characteristics and Effectsmentioning

confidence: 99%

Adjuvants and herbicidal efficacy – present status and future prospects

Zabkiewicz

2000

Weed Research

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The in¯uence of adjuvants on spray liquid behaviour and herbicide performance is reviewed. Total formulation ecacy can be expressed as a function of [deposition:retention:uptake: translocation:a.i. toxicity]. Adjuvants in¯uence the physico-chemical and plant interactions involved for each factor. Deposition eciency of spray droplets on to a target is dependent largely on the droplet spectrum, whereas retention performance is dependent on plant leaf surface character, orientation and canopy architecture, as well as droplet volume, velocity and dynamic surface tension eects. Uptake into plant foliage is aected by the leaf surface wax, cuticle age and composition and species variability. Uptake can be improved through appropriate formulation to provide either stomatal in®ltration or much greater and faster cuticular absorption of the active ingredient. The inherent translocation capability of the a.i. is not aected directly by adjuvants, which are relatively immobile, but they can increase the mass of absorbed a.i. translocated, as a consequence of improved uptake or may reduce it as a result of localized contact phytotoxicity. Considerable progress has been made in developing models of spray droplet deposition, adhesion and retention, as well as uptake. In future, individual models may be combined to provide an integrated formulation ecacy decision support system.

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“…Contact injury is the damage caused to leaf tissue after spray droplet contact and is not directly attributable to the active ingredient alone. It can develop rapidly, as was observed in several experiments in this study.Contact injury has been shown to isolate and confine the active ingredient physiologically to the site of penetration, thereby decreasing final efficacy Forster, Zabkiewicz, Murray, and Zedaker (1997). found lower translocation of triclopyr out of woody species leaves where there was greater or earlier development of contact injury.There is uncertainty regarding the role of contact injury in control of dense infestations of wilding conifers using current operational control methods.…”

mentioning

confidence: 99%

Effect of dose and adjuvant on uptake of triclopyr and dicamba into Pinus contorta needles

Rolando

Gaskin

Horgan

et al. 2020

Plant Enviro Interactions

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Why this research Matters Management of dense infestations of wilding Pinus contorta in New Zealand requires high doses of herbicides; 18 kg active ingredient (a.i.) ha−1 triclopyr and 5 kg a.i. ha−1 dicamba are used in combination with a complex mix of adjuvants (methylated seed oil, non‐ionic surfactant and ammonium sulfate) and other active ingredients. From the perspective of cost and environmental impact there is a need to reduce the complexity of this tank mix and the rates of active ingredients. Using radiolabelled herbicides, this study evaluated the effect of dose and adjuvants (crop oils, non‐ionic surfactants, and organosilicones) on needle injury and uptake of triclopyr and dicamba into P. contorta needles at 24 hr or 7 days after treatment (DAT). The uptake of triclopyr decreased significantly with increasing concentration (0.75%–6%) resulting in the highest uptake dose at the equivalent of 18 kg a.i. ha−1 triclopyr at 7 DAT. When applied at 18 kg a.i. ha−1, none of the adjuvants tested significantly increased the uptake of triclopyr (applied as Grazon®), with ~50% uptake occurring at 7 DAT. The uptake of dicamba (applied as Kamba® at 5 kg a.i. and 10 kg a.i. ha−1) was significantly affected by dose and adjuvants. The uptake of dicamba applied at 5 kg a.i. ha−1 was low at 7 DAT with no adjuvant (31%); however, use of a methylated seed oil doubled the uptake. When triclopyr and dicamba were applied together, there was no evidence that either active ingredient negatively affected uptake of the other, with triclopyr enhancing uptake of dicamba. These results show potential to reduce the amount of herbicide used for conifer control without compromising efficacy.

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Contact phytotoxicity of triclopyr formulations on three plant species in relation to their uptake and translocation

Cited by 6 publications

References 7 publications

Physical and physiological pathways of off-target triclopyr movement and associated non-target injury following basal bark application

Physical and physiological pathways of off-target triclopyr movement and associated non-target injury following basal bark application

Adjuvants and herbicidal efficacy – present status and future prospects

Effect of dose and adjuvant on uptake of triclopyr and dicamba into Pinus contorta needles

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