This page is designed to help you understand and navigate the specialized vocabulary used in the world of herbicides. Whether you are a farmer, a gardener, or simply someone interested in learning more about herbicides, this glossary provides clear and concise definitions of key terms.
Inside this glossary, you will find explanations for terms such as active ingredient, selective herbicide, pre-emergent herbicide, post-emergent herbicide, and many more.
If you are looking to understand the labels on herbicide products, learn about different ways to use herbicides, or just expand your knowledge in this field, this glossary will be helpful.
Contents
Glyphosate
Glyphosate is a chemical substance and active ingredient that is widely used as a herbicide. It belongs to the class of phosphonic acids and is derived from the reaction between the methyl group of methyl phosphonic acid and the amino group of glycine.
Isopropylamine salt is a form of glyphosate that is commonly used in herbicides. In this form, glyphosate is a water-soluble salt formed by combining glyphosate acid with isopropylamine. This improves the herbicide’s solubility and stability.
2,4-D (2,4-dichlorophenoxyacetic acid)
2,4-D is a systemic herbicide that selectively targets and controls most broadleaf weeds in various settings while having little to no impact on most grasses.
This herbicide was developed during World War II and has been used as a selective herbicide for over 75 years, making it one of the oldest and most widely available herbicides in the world.
Triclopyr BEE (3,5,6-trichloro-2-pyridinyloxyacetic acid, butoxyethyl ester)
Triclopyr BEE is a synthetic, selective herbicide that is systemic in nature, meaning it targets and controls only particular plant species. This man-made herbicide was first developed and registered in 1979 for use mostly in forestry but has since been used in other types of settings.
Aminopyralid
Aminopyralid is a selective systemic herbicide that belongs to the pyridine group of chemicals, along with clopyralid, picloram, and triclopyr. It was first approved for use in the US in 2005 under the name Milestone and has since been marketed under different names such as Grazon. Aminopyralid should be used with caution, as it can persist in soil for a long time and affect crops such as vegetables and ornamental plants.
Picloram
Picloram is a systemic herbicide that belongs to the chemical family of pyridine acids. It persists in soil for several months after application and makes it difficult to establish new plants in the treated areas. It can be used as a post- and pre-emergent treatment.
This synthetic herbicide is considered a restricted-use pesticide. This means that only licensed applicators are allowed to work with it.
Imazapyr
Imazapyr is a non-selective systemic herbicide that is part of the Imidazolinones family. It can be used as a pre-and post-emergent treatment to control weeds. Imazapyr’s mode of action involves absorption by both the foliage and root system of plants, disrupting the production of certain amino acids and affecting weed growth and development. It has a long-lasting effect and can persist in soil for several months after application.
Fluroxypyr
Fluroxypyr is a selective and systemic herbicide that is commonly used as a post-emergent treatment to control a range of broadleaf weeds in agricultural and non-crop areas. It belongs to the class of synthetic auxins, which are plant hormones that interfere with the plant’s growth and development.
This herbicide is absorbed by the plant and moves throughout its tissues by mimicking the natural auxins in the plant.
Thiencarbazone-methyl
Thiencarbazone-methyl is a selective herbicide that works as an ALS (acetolactate synthase) inhibitor. This herbicide is classified under the sulfonylaminocarbonyl-triazolinone family and works by inhibiting the biosynthesis of certain essential amino acids in the target plants. It can be used as a pre-emergent or post-emergent selective herbicide to control different types of broadleaf weeds in corn.
Isoxaflutole
Manufactured by Bayer CropScience, Isoxaflutole is a selective herbicide registered for weed control in field corn from 1998 to 2004. It is effective against certain broadleaf and grass weeds in both field corn and soybean crops.
Isoxaflutole belongs to the isoxazoline family of herbicides and is typically applied as a pre-emergent treatment to the soil before weeds emerge and crops are planted. It has a relatively long residual activity in the soil, which makes it effective against new weed growth for an extended period.
MCPA
MCPA, also known as 2-Methyl-4-chlorophenoxyacetic acid, is a selective systemic post-emergence herbicide. As a synthetic auxin herbicide, it acts systemically and targets broadleaf weeds.
MCPA has been used as a herbicide since 1945, effectively mimicking the growth hormones of weeds and causing their death from within. In its pure state, MCPA is a powdered substance with a brown color.
Dicamba
Dicamba or 3,6-dichloro-2-methoxybenzoic acid is a selective systemic herbicide commonly used for post-emergent treatment. It controls both annual and perennial broadleaf weeds by disrupting the metabolic processes of the targeted plants.
First registered in 1967, this herbicide includes a chlorinated compound of o-anisic acid. It is available under various brand names, including Dianat, Banvel, Diablo, and Vanquish.
Dimethenamid-P
Dimethenamid-P is a pre-emergent herbicide that belongs to the chloroacetamide family of compounds, and it is commonly used in agricultural, horticultural, and turfgrass settings.
