Hormone herbicides

The revolution in selective weed control came about in the early 1940s with the discovery of the hormone herbicides 2,4-D and MCPA (see Section 3.3 on Auxin-type herbicides). These compounds were truly selective and very active. They controlled broad-leaved weeds in cereal crops when applied post-emergence. 

Clinical analysis, immunoassays Proteins, hormones, herbicides, drugs Sensitivity is enhanced combined with fluorescence resonance energy transfer, homogeneous assays... 

Ylidenebutenolides of general constitution (42) have been reported amongst the products of metabolism of the hormone herbicides 4-chloro-, 4-chloro-2-methyl-, and 2,4-dichloro-phenoxyacetic acids (44, 45, 46). 

Thiiranes (77) show some juvenile hormone activity, but the epoxide is often more active. Thiophosphates of 2-mercaptomethylthiirane are strong contact insecticides 2-chloromethylthiirane and4-vinyl- 1,2-epithiocyclohexane are nematocides. Severalthiirane 1 -oxides are reported to be insecticides, molluscicides and herbicides (68USP3413306). 1,2-Epithio-1,2,3,4-tetrahydronaphthalene is a mild herbicide. 

Prohibit the advertisement, supply, storage and use of pesticides unless they have been approved. Pesticides includes herbicides, fungicides, wood preservatives, plant growth hormones, soil stenlants, bird or animal repellants. 

Crump, D. et al., Exposure to the herbicide acetochlor alters thyroid hormone-dependent gene expression and metamorphosis in Xenopus laevis, Environ. Health Perspect., 110, 1199, 2002. 

It is important to keep in mind that any extraction of organic matter from soil will include both naturally occurring organic matter and organic contaminants. Separating the two at some later stage of analysis is thus an essential analytical step. For example, extraction of soil with hexane or dichloromethane will extract both l,l,l-trichloro-2,2-di(4-dicholorphenyl)ethane (DDT), a contaminant, and octadecanoic acid, a natural fatty acid. Also, the herbicide 2,4-dichlorophenoxy acetic acid, a contaminant, and indole-3-acetic acid, a natural plant hormone, are both extracted by water (see Figure 12.3). These... 

Uses Plant hormone defoliant. Formerly used as a herbicide. Banned by the U.S. EPA. 

Herbicides are designed to kill plants, not animals, and in general have lower mammalian toxicity than insecticides. Most herbicides interfere with plant hormones or enzymes that do not have any direct counterpart in animals. The most serious human health concerns have been related to contaminants of the primary chemical herbicide. There is an enormous amount of animal and some human toxicity data on 2,4-D and 2,4,5-T, but it now appears that much of this toxicity is caused by the contaminant TCDD. Military personnel exposed to Agent Orange, often contaminated with TCDD, reported birth defects, cancers, liver disease, and other illness. These concerns led to improvement in the manufacturing process to reduce TCDD contamination and ultimately to a reduction in use of 2,4-D herbicides. There is also concern that some herbicides may affect wildlife. For example, atrazine, a persistent herbicide, may adversely affect frogs. Persistence of herbicides may also... 

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