Relative Activity of Four Triclopyr Formulations

Abstract

Triclopyr is a synthetic auxin herbicide currently available as a triethylamine salt, butoxyethyl ester, pyridinyloxyacetic acid, or choline salt. The formulation of a herbicide has the potential to impact its activity; therefore, the objective of this study was to determine the relative activity of these four triclopyr formulations. Greenhouse dose–response studies were conducted twice at the University of Florida in 2015. The four formulations were foliar applied at rates ranging from 17 to 1,121 g ae ha−1to 2- to 3-leaf soybean, sunflower, tomato, and cotton. The amine salt formulation provided the lowest ED50values in tomato and sunflower (22.87 and 60.39 g ha−1, respectively); whereas in soybean, amine and choline formulations provided the lowest ED50values (22.56 and 20.95 g ha−1, respectively). No differences between formulations were observed in cotton. These data suggest that (1) the amine salt formulation of triclopyr might be more active than the others on tomato and sunflower, and (2) the amine and choline salt formulations might be more active than the others on soybean. Further work must be conducted to determine whether there are differences among these formulations under a range of field conditions and target species. In addition, other important management factors such as applicator safety, volatility potential, and cost should be considered when choosing the best formulated product to be applied.

Relative activity comparison of aminocyclopyrachlor to pyridine carboxylic acid herbicides

“…Aminocyclopyrachlor (Method 50SG®, Bayer CropScience, Research Triangle Park, NC), aminopyralid (4-amino-3,6-dichloro-2-pyridinecarboxylic acid; Milestone®, Corteva Agriscience, Wilmington, DE, 240 g ae L −1 ), picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid; Tordon 22K®, Corteva Agriscience, 240 g ae L −1 ), and clopyralid (3,6-dichloro-2-pyridinecarboxylic acid; Stinger®, Corteva Agriscience, 360 g ae L −1 ) were applied at doses of 0, 0.25, 1, 4, 16, 64, 256, and 512 g ae ha −1 . Based on previous research by Dias et al (2017), triclopyr ([(3,5,6-trichloro-2-pyridinyl) oxy] acetic acid; Remedy Ultra®, Corteva Agriscience, 480 g ae L −1 ) was applied at a different rate titration (0, 1, 4, 16, 64, 300, 650, and 1,300 g ae ha −1 ) to ensure a full range of responses were exhibited. Herbicides were applied once plants reached the 2-to 3-leaf growth stage, approximately 20 d after planting (DAP).…”

An outlook ofFMC's current and future herbicide‐resistance management strategies

“…Effective use, product stability under challenging weather conditions and product stewardship are paramount justifications for FMC in using extensive resources to discover superior formulations. Application of an effective herbicide formulation facilitates proper uptake of the active ingredient by targeted weeds, and may reduce volatility or drift that could otherwise result in weeds being exposed to lower than required doses of chemistry, and increase the chances of non‐target (quantitative) resistance 25 . Some examples of FMC's outstanding efforts in formulation technology include a microencapsulated oil‐soluble formulation of clomazone 26 .…”

“…Application of an effective herbicide formulation facilitates proper uptake of the active ingredient by targeted weeds, and may reduce volatility or drift that could otherwise result in weeds being exposed to lower than required doses of chemistry, and increase the chances of non-target (quantitative) resistance. 25 Some examples of FMC's outstanding efforts in formulation technology include a microencapsulated oilsoluble formulation of clomazone. 26 Microencapsulation improved the delivery of an appropriate clomazone dose to target species while avoiding volatility that may lead to off-target movement causing exposure of targeted species to reduced dose, and even exposure of non-target species to herbicide, creating an unintended selection pressure.…”

Soybean dose–response to 2,4‐D and dicamba at vegetative and reproductive growth stages

“…Herbicide activity can sometimes change based on the formulation of the parent molecule. [36][37][38][39][40] Despite the recent introductions of dicamba-resistant crop cultivars that require low-volatile formulations, several other dicamba formulations are also widely used in monocot crop systems since the spread of glyphosateresistant weed species. 5,41,42 However, little is known of soybean's response to dicamba as a function of herbicide formulation.…”