摘要:

AbstractThe eukaryotic cell membrane is thought to consist of a mobile bilayer of phospholipid, sometimes intercalated with sterols, in which peripheral and transmembrane proteins are embedded. This provides a model whereby the mode of action of many fungicidal and herbicidal compounds can be rationalised and understood. Some compounds, such as the polyene antibiotics, steroidal saponins and certain phytoalexins, induce membrane malfunction by direct insertion, often complexing with vital components. Others, such as paraquat and the nitrodiphenyl ether herbicides, cause membrane damage by inducing lipid peroxidations. Furthermore, there are many compounds, including the sterol‐biosynthesis‐inhibiting fungicides and the aryloxyphenoxypropionate and cyclohexanedione herbicides, which interfere with the biosynthesis of membrane components. Because membrane structure is fundamentally similar in eukaryotes, it is important to discover the reasons for any differential toxicity displayed by these compounds and, if necessary, to find ways of optimising desirable patterns of selectiv

ISSN:0031-613X    

DOI:10.1002/ps.2780300202

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA gas chromatographic method, using electrolytic conductivity detection, is presented for the determination of 2,4‐0 as its methyl ester in triticale (X Triticosecale Wittmack). The method was used to monitor the dissipation of 2,4‐0 residues in triticale over a growing season at two sites following post‐emergence application of the dimethylamine salt of 2,4‐D at 0.56 kkg ha−1. Initial residues, in the order of30 mg kg−1. on the day afer application (3‐ to 4‐leaf stage of the crop), decreased to non‐detectable levels in the mature straw and seed. Recoveries of 2,4‐D were greater than 90% fiom green tissue fortified at 0.1 mg k−1., and in the order of 75% from seed fort

ISSN:0031-613X    

DOI:10.1002/ps.2780300203

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe effects of bifenox (methyl 5‐(2,4‐dichlorophenoxy)‐2‐nitrobenzoate) and oxadiazon (5‐tert‐butyl‐3‐(2,4‐dichloro‐5‐isopropoxyphenyl)‐1,3,4‐oxadiazol‐2(3H)‐one on photosynthetic activity were investigated in isolated chloroplasts, and on respiratory activity in isolated mitochondria. The global effects of these chemicals were also investigated on cucumber cotyledon pieces. It was found that, in vitro, bifenox and oxadiazon acted on cotyledon pieces as typical diphenyl ether herbicides, causing complete pigment bleaching, even at low concentrations. In addition, bifenox and oxadiazon were shown to inhibit the photosynthesis process at the chloroplast level. At concentrations of up to 40‐50 μM, oxadiazon and bifenox were observed to inhibit fully the light‐dependent oxygen evolution of spinach class A chloroplasts, oxadiazon acting preferentially on electron transfer at the PS II level whereas bifenox acted on the photophosphorylation process. Comparison of the amounts of herbicide needed to inhibit photosynthesis and to cause bleaching of cucumber pieces leads to the conclusion that photosynthesis inhibition by bifenox and ox

ISSN:0031-613X    

DOI:10.1002/ps.2780300204

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe excretion and metabolism of cis + trans‐[14C‐benzyl] cypermethrin has been compared in quail, rat and mouse. Radioactivity was rapidly eliminated by quail dosed orally with [14C]cypermethrin (2 mg kg−1), as was the case in the rat and the mouse. When the birds were dosed intraperitoneally (IP) with the14C‐labelled pyrethroid, radioactivity was excreted more slowly than after oral dosing, and almost 20% of the IP dose of14C remained in the tissues after 7 days. Both mammalian species excreted [14C]cypermethrin more rapidly than did the avian species after IP administration, and less than 6% of the dose remained in their tissues after several days. The biotransformation of the pyrethroid was more complex in the avian species (34 metabolites) than in the two mammals (some 10 metabolites in each species). In quail the predominant reactions were ester bond cleavage of cypermethrin together with either aromatic hydroxylation or amino acid conjugation of the 3‐phenoxybenzyl moiety. The hydroxylated derivatives were eliminated mainly as sulphates. 3‐Phenoxybenzoic acid was conjugated with a variety of amino acids including glycine, taurine, glutamic acid, serine, α‐N‐acetylornithine and the dipeptide glycylualine. The last two conjugations are unique to avian species. The major metabolite of cypermethrin in the rat was the sulphate conjugate of 3‐(14‐hydroxyphenoxy)benzoic acid, whereas in the mouse the major products were 3‐phenoxybenzoic acid and its taurine conjugate. Thus, in the mammalian species where hydroxylation was maximal, amino acid conjugation was a minor metabolic route und vice versa. However, in the quail, aromatic hydroxylation and amino acid conjugation of the 3‐phenoxybenzyl moiety of cypermethrin were both major reactions. The influence of the rates and sites of metabolism, and of the enzymology of amino acid conjugation, in determining this species difference are discussed. The rapid metabolism of cypermethrin to a variety of polar conjugates that are readily excreted, together with the low brain sensitivity of birds compared with mammals to its neurotoxic effects, explains the low acute toxicity of this py

ISSN:0031-613X    

DOI:10.1002/ps.2780300205

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractOff‐target deposit has been quantified from various silvicultural glyphosate application methods and an estimate made of the buffer‐zone widths required around water to protect fish and their invertebrate food species from possible toxicological effects. To overcome the difficulty of estimating different buffer widths to meet the various use conditions encountered, a realistic worst‐case scenario was chosen for small‐drop drift and data were collected accordingly. Three glyphosate application methods were tested, employing a helicopter equipped with a ‘Microfoil’ boom, a ‘Thru Valve Boom’ and D8‐46 hydraulic nozzles respectively. Airborne glyphosate and off‐target glyphosate deposits on ground sheets and foliar surfaces were measured at downwind distances between 50 and 200 m from multiple overlaid crosswind swaths. Over this distance airborne glyphosate decreased by factors of 3‐130, ground deposits by factors of 4‐2200, and foliar deposits by factors of 5‐100. In general, airborne glyphosate and off‐target deposit was highest from the D8‐46 application, and lowest from the ‘Microfoil’ boom application. Using these measurements, mathematical equations were formulated to predict glyphosate deposits on water surfaces downwind of multiple swath applications, and calculations made for 100‐ha applications. Large‐drop drift was also calculated using a ballistic model. An estimate was then made of buffer widths required around water bodies to prevent toxicological effects from small‐ and large‐drop drift, using reported glyphosate toxicities to salmon, rainbow trout and various aquatic invertebrates. A buffer width of 25 m around water bodies limits mortality in populations of salmon, rainbow trout and aquatic invertebrates to less than 10% for the application methods employing the ‘Microfoil’ and ‘Thru Valve’ Boom. For the third ap

ISSN:0031-613X    

DOI:10.1002/ps.2780300206

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe pro‐insecticide bis‐(1‐(4‐chlorophenyl)‐4‐(pyrid‐3‐yl)‐2,3‐diazabutadien‐1‐yl)disulfide,Iis photochemically transformed to the aphicidally active 5‐(4‐chlorophenyl)‐2‐(pyrid‐3‐y

ISSN:0031-613X    

DOI:10.1002/ps.2780300207

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe decomposition of the herbicide diclofop‐methyl (methyl (RS)‐2‐(4‐(2,4‐dichlorophenoxy)phenoxy)propionate), on homoionic Ca‐, Na‐ and K‐montmorillonite in hydroalcoholic suspension was investigated. The results show that the solvolysis of the pesticide affords two products: diclofop (RS)‐2‐(4‐(2,4‐dichlorophenoxy)phenoxy)propionic acid) and diclofop‐ethyl (ethyl (RS)‐2‐(4‐(22,4‐dichlorophenoxy)phenoxy)propionate). The former is always the main product of hydrolysis on the Ca‐, Na‐ and K‐clays, whereas the latter, arising from a transesterification reaction, is favoured only by the presence of Ca‐and Na‐clays. The solvolysis reaction follows the adsorption of the herbicide on the clay, as evidenced by the shift of the IR stretching value of the ester group of the molecule, depending on

ISSN:0031-613X    

DOI:10.1002/ps.2780300208

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe effectiveness of various fungicide formulations containing carboxin and thiabendazole in eradicating teliospores of Tilletia controversa (dwarf bunt) from winter wheat seed was evaluated in the laboratory and the field. In the laboratory tests, the viability of teliospores washed from treated infested seed was greatly reduced as compared to the viability of teliospores washed from untreated infested seed, suggesting that carboxin and thiabendazole were primarily fungicidal. Field tests in two different years were established to determine if teliospores from treated infested seed could infect nearby untreated noninfested seed. Formulations containing carboxin were highly effective in reducing infection of healthy seed. No dwarf bunt infected plants developed in either year from seed treated with ‘Vitaflo 250’. Furthermore, seedborne common bunt caused by Tilletia foetida was nearly eradicated by carboxin‐containing formulations in one field test. Carboxin treatment of winter wheat seed infested with dwarf bunt teliospores will greatly reduce the danger of introducing this pathogen into new

ISSN:0031-613X    

DOI:10.1002/ps.2780300209

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractSeveral thiosemicarbazones of 2‐formyl‐ and 2‐acetylpyridine dialkylated on N4and non‐alkylated on N2were found to be broad‐spectrum protectant fungicides with activity particularly against oomycetes. The effect of some of the compounds on chitin biosynthesis was studied, but the low inhibitory activity observed combined with the fungicidal activity spectrum—particularly the high activity against oomycetes—excludes this as their main mode of action. Attempts at enhancing the systemic properties of the compounds by chemical modific

ISSN:0031-613X    

DOI:10.1002/ps.2780300210

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

Abstract4‐Amino‐6‐methyl‐3‐phenylamino‐1,2,4‐triazin‐5(4H)‐one alters the integrity of chloroplasts in barley (Hordeum vulgare L. var. Hassan) leaves as judged by their sedimentation profiles in linear gradients of sucrose. This effect may be related to the inhibition caused by 4‐amino‐6‐methyl‐3‐phenylamino‐1,2,4‐triazine‐5(4H)‐one of both ascorbate peroxidase and superoxide dismutase activities, and could thus be explained by an accumulation of toxic reduced‐oxyge

ISSN:0031-613X    

DOI:10.1002/ps.2780300211

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY