Canada Thistle (Cirsium arvense) and Pasture Forage Responses to Wiping with Various Herbicides

Abstract

Weed-wipers may provide effective weed control while minimizing the application of herbicide to nontarget species in rangeland and pasture. To date, few herbicides are recommended for use in weed wiping systems. We assessed Canada thistle and non–Canada thistle herbage responses in two experiments in pastures, the first examining wiped glyphosate, the second comparing glyphosate with three broadleaf herbicides at cost-equivalent concentrations [on a volume to volume (v/v) dilution basis]. In both studies, wiping with a glyphosate solution (33% v/v, equivalent to a one to two dilution ratio of herbicide to water) resulted in lower Canada thistle density and biomass than check plots, with control lasting up to 2 yr. However, significant reductions in grass biomass also occurred and were associated with an increase in the abundance of weedy annual forbs. In contrast, wiping with a concentrated solution of clopyralid (2% v/v), picloram plus 2,4-D (20% v/ v), or 2,4-D plus mecoprop plus dicamba (24% v/v), resulted in similar levels of Canada thistle control but no reduction in grass biomass. Despite direct application of herbicides to tall weeds, clover species in mixed stands were injured. In grass-dominated pastures, wiping with broadleaf herbicides was superior to nonselective glyphosate because the former more effectively balanced Canada thistle control with the retention of grass production.

Relationships between the stereochemistry and biological activity of fungal phytotoxins

“…152 However, herbicides recommended for control of these perennials are limited and low in selectivity. [153][154][155] Search for efficacious biocontrol microorganisms and natural herbicides has been active and numerous surveys have been carried out to find pathogens on Canada thistle, [156][157][158] whereas those of perennial sowthistle have not been studied extensively. 159 Stagonospora cirsii and Ascochyta sonchi (syn.…”

Seasonal dynamics of ground cover in Cirsium arvense – a basis for estimating grazing losses and economic impacts

“…While potentially of value for comparing between different weed control treatments in field experiments (Hartley & James, 1979;Mitchell & Abernethy, 1995) or for comparing infestation levels between regions (Bourdôt & Kelly, 1986;Cripps et al, 2010;Blackwell et al, 2011), these 'single-point-in-time' estimates of the weed's cover are not, alone, useful for quantifying economic effects, as they do not capture the withinyear seasonal dynamics of the system. This problem is inherent in estimates of the weed's aerial shoot density and biomass as predictors of herbage loss in a grazed pasture when such estimates are made at a single point in time, as in the experiments on the management of C. arvense in pastures in Alberta, Canada (Grekul & Bork, 2004;Bork Edward et al, 2005;De Bruijn et al, 2010).…”

Minimizing environmental impacts of grassland weed management: can Cirsium arvense be controlled without herbicides?

“…Herbicide control was tested by applying the selective compound clopyralid (Dow Shield; Dow AgroSciences Ltd, Hitchin UK) in June (D) using a trailed weed wiper (C‐Dax tm Eliminator; C‐Dax Europe Ltd., Wymondham, Norfolk, UK). Clopyralid is one of the more effective herbicides for selective control of C. arvense when applied through a weed‐wiper in pastures containing intolerant non‐target species (Boeroom and Wwyse, 1988; Grekul et al. , 2005).…”

“…Creeping thistle has an agronomic impact by reducing the availability of pasture to grazing and previous researchers have assessed this impact using shoot cover, density and/or biomass (Edwards et al. , 2000; Grekul et al. , 2005; Mesbah and Miller, 2005).…”