Efficacy of five different formulations of clopyralid on Cirsium arvense (L.) Scop, and Polygonum convolvulus L

Abstract

Experiments were conducted in a controlled environment growth room to compare the phytotoxicity of five formulations of clopyralid and to determine the effect of post-treatment simulated rainfall applications on the efficacy of these formulations. Clopyrahd, formulated as the acid, monoethanolamine salt, potassium salt, 2-ethylhexyl ester or 1-decyl ester was applied to Cirsium arvense or Polygonum convolvulus at the 8-10 and 4-6 leaf stage of development, respectively.Based on the shoot and root dry weight data from both species, the 2-ethylhexyl ester was consistently less phytotoxic than the other four formulations. With respect to Cirsium arvense shoot and root dry weight, there was no difference in efficacy between the acid, monoethanolamine salt, potassium salt and 1-decyl ester. Root dry weight changes of Polygonum convolvulus did not correlate well with an increase in dose of the five formulations. Maximum increase in stem diameter of Polygonum convolvulus occurred after application of 100 g a.e. ha~' of the acid, monoethanolamine salt, potassium salt and 1-decyl ester whereas with the 2-ethylhexyl ester, the maximum increase occurred after application of 200 g a.e. ha"'. Simulated rainfall was applied 3, 6, 9 or 12 h after application of 200 g a.e. ha~' of the five clopyralid formulations to both species. Rainfall reduced the efficacy of clopyralid, regardless of the formulation or species. The 2-ethylhexyl ester was less efficacious than the other four formulations, irrespective of the timing of simulated rainfall. Efftcacite de cinq formulations differentes de clopyralid sur Cirsium arvense (L.) Scop, et Polygonum convolvulus L. Des essais ont et6 conduits dans des chambres de croissance en milieu controle pour comparer la phytotoxicite de cinq formulations de clopyralide et pour determiner l'effet d'une pluie artificielle apres le traitement sur l'efficacitd e ces formulations. Le clopyralid formule comme acide, sel monoethanolamine, sel de potassium, 2-ethylhexyl ester ou 1-decyl ester a et6 applique sur Cirsium arvense ou Polygonum convolvulus aux stades respectifs de 8 a 10 feuilles et de 4 a 6 feuilles. En se basant sur les poids sees des tiges et racines des deux especes, on a vu que le 2-ethylhexyl ester 6tait notamment moins phytotoxique que les 4 autres formulations. En regard des poids sees des tiges et racines de Cirsium arvense, il n'y a pas eu de difference d'efficacite entre l'acide, le sel monoethanolamine, le sel de potassium et 1decyl ester. Les changements du poids sec racinaire chez Polygonum convolvulus n'etaient pas bien correl6s avec une augmentation de la dose des cinq formulations. Le maximum d'augmentation du diamfetre de la tige de Polygonum convolvulus a 6t6 observe apres l'application de 100 g ha~' d'acide, sel monoethanolamine, de sel de potassium et de 1-decyl ester tandis qu'avec le 2-ethylhexyl ester, le maximum a ete observe aprds une application de 300 g ha"'. Des pluies artificielles ont et6 faites 3, 6, 9 ou 12 h aprfes l'application de 200 g ha~' des cinq formulatio...

Relative Activity of Four Triclopyr Formulations

“…This may explain the lower activity observed for the ester formulation in this study. These findings tend to agree with those of Kloppenburg and Hall (1990b). These authors compared, under controlled environment conditions, the phytotoxicity of five different clopyralid formulated products—the acid, monoethanolamine salt, potassium salt, 2-ethylhexyl ester, and 1-decyl ester—all applied to Canada thistle and wild buckwheat at the 8- to 10-leaf and 4- to 6-leaf stages of development, respectively.…”

“…This may explain the lower activity observed for the ester formulation in this study. These findings tend to agree with those of Kloppenburg and Hall (1990b). These authors compared, under controlled environment conditions, the phytotoxicity of five different clopyralid…”

“…However, Bovey et al (1970) found similar or slightly higher activity with an isooctyl ester than the potassium salt formulation of picloram for woody plant control in tropical conditions in Puerto Rico. Kloppenburg and Hall (1990b) found greater absorption of an acid formulation of clopyralid in Canada thistle [ Cirsium arvense (L.) Scop.] and wild buckwheat ( Polygonum convolvulus L.) than other salt and ester formulations.…”

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.…”

Tolerance of Sweet Corn (Zea mays) to Clopyralid and EF-689

“…Clopyralid is especially effective against Canada thistle and honey mesquite (Prosopis glandulosa Torr.) (3,8).…”