Influence of hard water on 2,4-D formulations for the control of dandelion

The herbicide 2,4-D is used in a variety of cropping systems, especially in grasses because it is a selective postemergence broadleaf herbicide. However, the most common formulation (2,4-D dimethylamine) is antagonized when mixed in hard water. The objective of this research was to determine which f...

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Bibliographic Details
Published in:Weed technology 2021-06, Vol.35 (3), p.371-379
Main Authors: Schortgen, Geoffrey P., Patton, Aaron J.
Format: Article
Language:English
Subjects:
2,4-D
Acids
amine
antagonism
Auxins
Calcium carbonate
Choline
Cropping systems
Diethanolamine
emulsifiable concentrate
Emulsifying agents
emulsion
Emulsions
ester
Experiments
Formulations
Greenhouses
hard water
Herbicides
Horticulture
Ingredients
Isooctyl ester
Loam soils
Proprietary
Salt
Salts
Water chemistry
Water hardness
water-insoluble
water-soluble
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Summary:The herbicide 2,4-D is used in a variety of cropping systems, especially in grasses because it is a selective postemergence broadleaf herbicide. However, the most common formulation (2,4-D dimethylamine) is antagonized when mixed in hard water. The objective of this research was to determine which formulations of 2,4-D or premixes of various formulations of synthetic auxin herbicides are subject to hard water antagonism. Formulations surveyed for hard water antagonism in the first experiment included 2,4-D dimethylamine, 2,4-D diethanolamine, 2,4-D monomethylamine, 2,4-D isopropylamine salt, 2,4-D choline salt, 2,4-D isooctyl ester, and 2,4-D ethylhexyl ester. Synthetic auxin formulation types in the second experiment included water-soluble, emulsifiable concentrates and emulsion-in-water. All formulations were mixed with both soft and hard water (600 mg CaCO3 L-1) and applied to dandelions to determine whether antagonism occurred in hard water. Water-soluble (amine and choline) 2,4-D formulations were antagonized by hard water, but water-insoluble (ester) 2,4-D formulations were not antagonized. Similar results were found by formulation type with water-soluble synthetic auxin premixes antagonized but emulsifiable concentrates not antagonized. Furthermore, water-soluble salt formulations were not antagonized when formulated in premixes with other synthetic auxin herbicides as an emulsion-in-water. This research demonstrates that all 2,4-D water-soluble formulations and water-soluble premixes with phenoxycarboxylic acid herbicides are subject to hard water antagonism. Formulations of 2,4-D containing emulsifying agents protect against antagonism by the water-insoluble nature of ingredients in their formulation. Nomenclature: 2,4-D; dandelion; Taraxacum officinale G.H. Weber ex Wiggers; MCPP; MCPA
ISSN:0890-037X
1550-2740
DOI:10.1017/wet.2020.135