Translocated herbicides

C2H4N4. A translocated herbicide, m.p. 157-159 C, used as a non-selective herbicide on fallow land or in established orchards. 

D. The most widely used herbicide at present is 2,4-D. As far as the selective use of 2,4-D on cereal crops is concerned, the amine formulations seem perfectly satisfactory. As a translocated herbicide, results are not too good. In some localities, 2,4-D has been effective in treating perennial weeds, but in other places results have been disappointing. The differences seem related to the movement of the material after it gets into the plant, and here the physiology of the plant, as well as the nature of the chemical, is concerned. 

Both compounds are rapidly translocated herbicides that selectively kill broad-leaved weeds. They mimic the natural auxin, indol-3-ylacetic acid, which is responsible for promoting cell elongation and hence cause unrestrained growth. This uses up all the available nutrients, leading to the death of the plant. A review of the pyridinecarboxylic acids has been published (B-75MI10702). 

Stage in life Cycle—Seedlings are very susceptible to herbicides and to most other weed control practices. Plants in the vegetative and early bud stages are very susceptible to translocated herbicides. Plants with seeds or in the maturity stage are the least susceptible to weed control practices. 

Sulfallate is a translocating herbicide, applied preemergence at rates of 3-6 kg active ingredient/ha at the soil surface or incorporated into the soil, against annual grass weeds and a few broad-leaved weeds, mainly on vegetable crops and ornamental plants. 

The cause in some of the cases is of a physical character. Herbicidal compounds poorly soluble in water are located in the upper layer of the soil, and are thus absorbed by the shallow-rooted weeds, which are killed while they do not reach the roots of the deep-rooted crop plants, which can grow unhindered. Translocation proceeding at different rates in tolerant and sensitive plants and the detoxication of the translocating herbicide through deposition in parts of the plant, such as the cell... 

Translocated herbicides are those which can move through the plant before acting on one or more of the growth processes. Some of these herbicides can be very effective at controlling perennial weeds, e.g. the control of couch by glyphosate. Good spray cover is not so important with this type of herbicide. 

Nonspecific disruption of membrane permeability was proposed for difenopenten-ethyl ethyl 4-[(4-trifluoromethyl)phenoxyl-2-pentanoate, which uncoupled and inhibited respiration in corn and soybean mitochondria. This was considered to be a secondary effect of this aryloxy-phenoxypropionate analogue (see Chapter 3) due to the relatively high in vitro concentration. A similar conclusion was made for another aryl-oxyphenoxypropionate, diclofop, which uncoupled state 4 respiration, inhibited state 3 respiration, and caused swelling of isolated wheat and wild oat mitochondria. The inhibition of respiration was proposed to be due to an effect prior to the electron transport chain, that is, an effect on succinate or malate dehydrogenase. A potent inhibition of state 3 respiration was also reported for the herbicide UK J72J (2-ethylamino-4-amino-5-thiomethyl-6-chloropyrimidine), with succinate as substrate.Difenzoquat also inhibits state 3 respiration in isolated wheat and wild oat mitochondria however, this was not thought to be a significant contribution to the chlorotic contact symptoms observed with this translocated herbicide. Difenzoquat also possesses a weak bipyridinium-type PSI electron acceptor activity which causes chlorosis. ... 

Uses Adjuvant, surfactant for use with translocating herbicides Features Enhances herbicide activity contains defoamer Reguiatory DOT not regulated... 

Uses Adjuvant, surfactant for use with translocating herbicides Features Enhances herbicide activity mixes quickly and easily with herbicides in cold and hard water conditions contains defoamer Reguiatory DOT not regulated Properties Flash pt. > 200 F... 

MCPB, 4-(4-chloro-2-methylphenoxy)-butyric acid, CiiHisClOj. A compound in itself harmless to plants, but when absorbed and translocated in the cells, CnHuClOs is converted to a powerful herbicide, and results in the death of the plant. Acts as a selective weedkiller. Other butyric acid derivatives used commercially are 2,4-Dg and 2,4,5-Tb, the butyric acid analogues of 2,4-D and 2,4,5-T. ... 

Biorational approaches have proven useful in the development of classes of herbicides which inhibit essential metaboHc pathways common to all plants and thus are specific to plants and have low toxicity to mammalian species. Biorational herbicide development remains a high risk endeavor since promising high activities observed in the laboratory may be nullified by factors such as limitations in plant uptake and translocation, and the instabiHty or inactivity of biochemical en2yme inhibitors under the harsher environmental conditions in the field. Despite these recogni2ed drawbacks, biorational design of herbicides has shown sufficient potential to make the study of herbicide modes of action an important and growing research area. 

Inhibitors must possess chemical and physical properties that will ensure absorption by root tips or penetration by foliar surfaces, and translocation to the active site. Once there they must assume the precise spatial configuration required to complement the molecular architecture of the active center if they are to block the key reaction. A comprehension of comparative biochemistry and information on how plants differ in the architecture of the reactive sites should assist in developing truly selective herbicides. 

Dinitroaniline herbicides show minimal plant systematic translocation properties with the majority of the absorbed residues in the root tissues. Metabolites identified include traces of Al-dealkylation, alkyl and aryl hydroxylation and nitro reduction products. Low levels of dinitroaniline herbicide residues have been reported in raw agricultural commodities according to Good Agricultural Practice. 

Because of the limited root uptake and slow rate of systemic translocation, the diphenyl ether herbicide residues detected in the aerial plant portion are low. 

Diphenyl ethers in the soil are absorbed by roots with limited translocation generally to the foliage. Low levels of herbicide residues can be expected when the compound is used in accordance with good agricultural practice. The parent diphenyl ether compound is defined as the residue of analytical and regulatory concern. 

Plant Bromacil is slowly absorbed and translocated in plants. Gardiner et al. (1969) reported 17% of the herbicide was translocated to the stems and leaves and 83% remained in the roots. A... 

D Acid 94-75-7 2.25 -1950 Herbicide A translocated phenoxy herbicide for use in cereals, grass, and amenity use... 

It is a broad-spectrum herbicide active both pre- and post-emergent. Studies with radiolabelled compounds ( ) show it to be rapidly translocated particularly to the meristematic regions. Translocation to the underground storage organs of perennial weeds prevents regrowth of these weeds. Most herbaceous and woody plants are controlled in the field at 0.4-1.0 kg a.e./ha whereas most woody plants require 0.7-3.0 kg a.e./ha (10). 

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