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At least 19 recordsLinked to original sources
PubMed1978

Herbicidal phenylalkylureas as possible mutagens I. Mutagenicity tests with some urea herbicides.

Substituted phenylalkylureas are widely used as herbicides. In the assay system of Friedman and Staub, which measures the inhibition of testicular DNA synthesis (DSI test), most of these substances showed a positive reaction, i.e. they depressed tnymidine incorporation significantly. Bacterial tests demonstrated a weak mutagenic activity, too; but in the micronucleus test the compounds were almost inactive. As one member of this group of chemicals--the herbicide monuron--is a recognized carcinogen, these results seem to indicate a possible hazard, but more investigations are needed to quantify this danger.

DNA↗
PubMed1976

[Liquid chromatographic parameters of groups of herbicidal active substances. I. Urea herbicides].

Because of the polarity of herbicidal urea derivatives, liquid chromatography is the most suitable method for their determination. The separation of a number of active substances is described. A versatile applicable ternary solvent mixture is used as the mobile phase. Several columns are tested for their separation performances and their capability to retain active substances and some known degradation products. To fully utilize the sensitivity of the photometric detector the UV spectra of the tested compounds are determined.

Chromatography, Liquid↗
PubMed2026

Herbicide Resistance Genes in Crops: Mechanisms, Progress, and Future Perspectives.

While previous reviews have largely focused on individual crops or single target-site mechanisms, the full-chain comparative landscape across major cereal crops remains unexplored. Here, we fill this critical gap by providing the first systematic, cross-crop comparative review that spans herbicide targets, resistance mechanisms, and breeding applications across four major cereals-rice, maize, wheat, and sorghum. Weed infestation is a serious constraint on crop production. Chemical weed control faces challenges such as herbicide resistance evolution and ecological risks. Developing herbicide-resistant varieties is a fundamental approach to achieve green and sustainable weed management. This review systematically summarizes research progress on herbicide resistance genes from three aspects: herbicide classification, resistance mechanisms, and crop breeding applications. It highlights key differences among four major cereal crops (rice, maize, wheat, and sorghum) in resistance-gene discovery and translational progress. Rice has the richest target-site resistance-gene resources. Maize leads in commercialization of transgenic herbicide resistance. Wheat focuses on endogenous precise editing due to genome complexity and regulatory constraints. Sorghum relies on specific mutations to serve cereal-legume intercropping systems. Based on this comparison, this review identifies the core trends in resistance breeding: from single-gene to multi-gene stacking, and from exogenous gene introduction to endogenous gene editing. It also points out common bottlenecks, including insufficient systematic mining of resistance-gene resources, lagging elucidation of non-target-site resistance regulatory networks, and strong genotype dependence in genetic transformation. Future efforts should focus on exploring broad-spectrum resistance genes, optimizing precise editing technologies, and developing sustainable resistance management strategies. This review provides a theoretical framework and practical references for molecular breeding of herbicide-resistant crops.

crop breeding↗
PubMed1979

Herbicidal potency of 1,1'-alkyl-4,4'-bipyridylium salts as a function of their physicochemical constants in duckweed.

Duckweed (Spirodela oligorrhiza, Kurz) is a sensitive indicator of 1,1'-alkyl-4,4'-bipyridylium salt (viologen) herbicidal potency. A homologous series of viologens were tested to determine relative herbicidal potency which was related to alkyl inductive and steric effects of N-alkyl side chains. Chlorosis was assessed after 48 hr of continuous illumination to establish herbicidal potency. Herbicidally effective concentrations were 2.7, 12, 236, 71, 31, 51, 13 and 43 microM for methyl (paraquat), propyl, isopropyl, butyl, methyl-pentyl, hexyl, octyl and benzyl viologen, respectively. A biphasic relationship of herbicidal potency versus steric effect was established in which compounds with the least bulky side chains were most phytotoxic. Comparison of rat lethality (acute, subcutaneous) and herbicidal potency of these compounds indicates that none of the viologens tested are less toxic to mammals than plants compared to the commercial herbicide methyl biologen (paraquat).

Animals↗
PubMed1978

Effect of some herbicides on the toxicity of certain molluscacides against Biomphalaria alexandrina snails.

Studies dealing with the effect of some herbicides on the molluscicidal action of certain molluscicides against B. alexandrina have been carried out. In the first part of the study the toxicity of 3 molluscicides (Copper sulphate, Niclosamide and Frescon) and 3 herbicides (Gramaxone, Preforan and Treflan) was tested individually. Results indicated that the molluscicides were more potent than the herbicides. In the second part, snails were exposed for 24 hr to one of the tested herbicides using LC0 or (Sub. lethal conc) then the toxicity of molluscicides was determined among the same snails. Data indicated that pre-exposure to herbicides caused a synergistic action with copper sulphate, while with Niclosamide and Frescon marked antagonistic effect was observed. In the third part molluscicides and herbicides were mixed in different ratios (1:2, 1:1 and 2:1) and the toxicity of the mixtures was tested. A synergistic effect was observed in the case of copper sulphate plus various herbicides especially with Treflan at 1:2 ratio. With Niclosamide and Frescon slight antagonistic effect was detected.

Animals↗
PubMedDate not supplied

Herbicidal treatments for control of Cannabis sativa L.

In order to test herbicides for the destruction of illicit stands of cannabis (Cannabis sativa L.) a series of commercially available herbicides were sprayed on glasshouse-grown plants having 2 to 6 leaves. The following herbicides caused complete kill or severe injury to cannabis plants: (a) herbicides with root and foliage activity--ametryn, atrazine, metribuzin, prometryn, terbutryne, diuron, fluometuron, linuron, methabenzthiazuron, phenobenzuron, ethofumesate, karbutilate, methazole and oxadiazon; and (b) foliar-acting herbicides with brief or no soil persistence--amitrole, bentazon, 2,4-D, diquat + paraquat, glyphosate and phenmedipham. In field experiments herbicides of the latter group, and ioxynil, metribuzin, and a MSMA-cacodylate mixture, caused death or severe damage to young cannabis plants. Glyphosate, ioxynil and bentazon destroyed developed cannabis plants. In glasshouse and field experiments the following herbicides applied to young cannabis plants caused marked deformations of stems, leaves and/or inflorescences: barban, butralin, dalapon, difenzoquat, dinitramine, diphenamid, IPC, napropamide, penoxalin, triffuralin, and U-27267.

Cannabis↗
PubMed2025

Stacked mutations in multi-copy AHAS genes enhance sulfonylurea herbicide resistance in soybean.

Weeds are a major factor that negatively impact crop yields. Developing herbicide-resistant germlines is crucial for efficient weed control. Sulfonylurea- and pyrimidinyl benzoate-based herbicides inhibit the function of acetohydroxyacid synthase (AHAS), a key enzyme in the biosynthesis of branched-chain amino acids in plants. To create soybean plants resistant to these classes of herbicides, we performed base editing of AHAS genes in Glycine max. A guide RNA was designed to target the codon for proline-182 in GmAHAS2, with the prediction that off-target base editing might also occur in the GmAHAS3 and GmAHAS4 genes. We selected six genome-edited soybean lines, each carrying distinct mutations in GmAHAS2, GmAHAS3, or GmAHAS4. These lines were treated with three different AHAS-targeting herbicides to evaluate resistance. The results show that the number of mutated GmAHAS genes and the mutation patterns significantly influence herbicide resistance.

Herbicide Resistance↗
PubMed2026

Pinpointing genomic regions conferring herbicide tolerance in cassava via genome-wide association mapping.

Cassava (Manihot esculenta Crantz) is a tropical crop of major socioeconomic importance, whose productivity can be limited by sensitivity to herbicides used for weed management. This study aimed to perform a genome-wide association study (GWAS) in 194 cassava genotypes to identify genomic regions associated with tolerance to the herbicides mesotrione, S-metolachlor, and chloransulam-methyl. The evaluations performed at 3, 6, 9, 15, and 30 days after application (DAA) were used to characterize the temporal progression of phytotoxicity. Based on this analysis, the phenotype obtained at 9 days after application (PhytoX9DAA) was selected for genome-wide association analyses because it represented the period of greatest symptom expression and the highest discrimination among genotypes. GWAS analyses were performed using de-regressed BLUPs and the MLM, MLMM, and BLINK models, incorporating kinship (K) and population structure (Q) matrices. Significant markers were detected across multiple chromosomes, and the corresponding genomic windows contained candidate genes with functional annotations related to herbicide response. The predominant functional categories included membrane transport, channel activity, signal peptide processing, protein phosphorylation, cellular signaling, and metabolic regulation. Key candidate genes included Manes.02G151900 and Manes.02G152700 (chromosome 2), associated with transmembrane transport and signal peptide processing; Manes.09G060900 (chromosome 9), associated with protein kinase activity, ATP binding, and protein phosphorylation; and Manes.15G083800 and Manes.15G084000 (chromosome 15), associated with S-adenosylmethionine-dependent methyltransferase activity, membrane-related functions, and protein phosphorylation. These genes participate in biochemical pathways involved in cellular signaling, membrane transport, and metabolic regulation that may contribute to herbicide tolerance. Overall, the results demonstrate that herbicide tolerance in cassava is a quantitative and polygenic trait governed by numerous small-effect loci. The integration of cellular signaling, metabolic regulation, and membrane transport supports the physiological resilience of the species under chemical exposure, providing valuable insights for breeding strategies and marker-assisted selection.

Genome-Wide Association Study↗
PubMed1979

Herbicide contamination and decontamination of well waters in Ontario, Canada, 1969-78.

OVER THE 10-YEAR period 1969-78, the waters of 237 wells were analyzed because of contamination from herbicide spillage in or near the well, complaints of impaired water flavor, or injury to seedling plants moistened with the well water. Herbicides were identified in 159 wells: 98 had a single herbicide, 46 had two, 12 had three, one had four, and another had five separate herbicides contributing to the contamination. Wells were grouped according to the mode of entry of the contaminant. Entry occurred most commonly as an aerial spray fdrift or in runoff. Serious contaminations were caused by spillage of herbicide concentrates and spray solutions in or around the well. Twenty-four of the contaminated wells were further investigated to determine the persistence of the contaminant and how to remove it. Some wells were decontaminated adequately to allow reuse within nine weeks, others required three years, and yet others had to be abandoned. Particularly persistent contaminants were amitrole, dinoseb, and picloram.

Herbicides↗
PubMed1977

Mutagenicity of the triazine herbicides atrazine, cyanazine, and simazine in Drosophila melanogaster.

Assays for dominant lethal mutations, sex-linked recessive lethal mutations, and chromosomal breakage, nondisjunction and loss were performed on Drosophila melanogaster males treated by injection or by larval feeding of the herbicides atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine), cyanazine [2-chloro-4-(1-cyano-1-methylethylamino)-6-ethylamino-1,3,5-triazine], or simazine [2-chloro-4,6-bis-(ethylamino)-1,3,5-triazine]. The three herbicides significantly increased the rate of apparent dominant lethals, but this reduction in egg hatch was probably due to physiologic toxicity to sperm. Atrazine significantly increased X-linked recessive lethals and X or Y loss after treatment by larval feeding. Injection of simazine elevated X-linked lethals, whereas treatment by larval feeding did not. None of these herbicides significantly increased partial loss of the Y chromosome nor sex chromosome nondisjunction. Much larger experiments are needed to determine with confidence the mutagenic potential of these herbicides.

Animals↗
PubMed1976

Evaluation and confirmation of an alkylation-gas-liquid chromatographic method for the determination of carbamate and urea herbicides in foods.

An alkylation technique using methyl iodide and sodium hydride in dimethyl sulfoxide has been evaluated for 3 carbamate and 7 urea herbicides in 9 foods. Recoveries ranged from 56 to 113%, depending on herbicide, concentration, and food type. Reproducibility was about +/-6% at 0.1 and 1.0 ppm. Identities of the herbicides were confirmed at these and lower levels by cleaving the aniline moiety from the alkylated herbicides with sodium methoxide in methanol, followed by gas-liquid chromatography on the same column as the parent compound. An electrolytic conductivity detector in the nitrogen mode was used for all analyses. Minimum detectable levels were in the range of 0.005-0.01 ppm in the foods studied.

Alkylation↗
PubMed1977

Fate and distribution of the herbicides 2,4-dichlor-phenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in the dogfish shark.

1. The urinary and biliary excretion, tissue distribution and metabolism of 14C-labelled 2,4-dichloro- or 2,4,5-trichloro-phenoxyacetic acids (2,4-D or 2,4,5-T) were measured in dogfish sharks, Squalus acanthias. 2. Both herbicides are extensively metabolized (greater than 90%) to the corresponding taurine conjugates, and are excreted predominantly via the urine, where ca. 70% of the administered dose appears within 4-6 days after treatment. 3. The highest tissue levels of 2,4-D or 2,4,5-T were found in liver and kidney. Penetration of both herbicides into the CNS was restricted. 4. Plasma elimination was rapid and the 0.5 for either phenoxyacetic acid was less than 45 min. Similarly, rapid clearance as seen from renal tissue. Final t0.5 values for muscle were about 2-3 days while the major organ showing 2,4-D or 2,4,5-T retention was the liver, where t0.5 values were about 5 days for both the herbicides. 5. The overall pharmacokinetics in the dogfish shark for these herbicides resembled those seen in some mammals.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1976

Microbial degradation of the thiolcarbamate herbicide, diallate, in soils and by pure cultures of soil microorganisms.

The disappearance of the herbicide, Avadex (40% diallate), from five agricultural soils (differing in either pH, carbon content, or nitrogen content), incubated under sterile and non-sterile conditions, was followed for a period of 20 weeks. Avadex was rapidly lost from microbiologically active soils, with over 50% of the applied (2.5 ppm) dosage disappearing within four weeks; losses from sterile soils were much slower with recoveries of over 50% after 20 weeks. Incubation of soil with Avadex to which 14C-labeled diallate had been added resulted in rapid formation of 14CO2 from microbiologically active samples and only very slow 14CO2 formation from sterile samples. Substantial quantities of radioactivity were retained as unextractable residues in both sterile and non-sterile soils after senven days incubation. From these data it was concluded that the disappearance of the herbicide from non-sterile soils was mainly due to microbial degradation and to binding of diallate or its metabolites as residues to undefined soil components. Losses from sterile soils were attributed to both binding of residues and to a slow chemical degradation. Avadex degradation by pure cultures was studied using representative fungi isolated from the five soils. Of the fungi tested, Phoma eupyrena, Penicillium janthinellum, and Trichoderma harzianium coudl degrade at least 20% of the applied (2.5 ppm) herbicide after ten days incubation. Degradation of Avadex in soil cultures of T. harzianum was found to be slower than degradation in liquid nutrient cultures.

Biodegradation, Environmental↗
PubMed1976

Comparative studies of instrumental and bioassay methods for the analysis of herbicide residues.

A study of the quantitative analysis of herbicide residues by both chemical and bioassay methods in soils is presented. Field and laboratory residue trials were carried out with a representative member of the following groups of herbicides: ureas, triazines, diphenylethers, phenoxyacetic acids, and dithiophosphates. Representative samples were taken at different time intervals, and degradation curves were established both by chemical methods and by two types of bioassay. Chemical analysis either separated active ingredient and metabolites by chromatographic techniques or compresied total residues. Bioassays were performed using either monocotyledons and dicotyledons or algae. The results obtained by chemical and bioassay analysis for the degradation rates of chlorotoluron, ametryn, 2,4-D and C 19490 showed a correlation coefficient of 0.914, indicating that the two methods gave almost identical results. Especially with the highly adsorbed urea and triazine herbicides, the uptake of biologically active material by test plants was slightly less than the solvent-extractable parent compound plus its metabolities, and so the absolute level of residues obtained by bioassay was lower. In the case of fluorodifen, the correlation between the methods was not established. The bioassay showed higher residues and slower degradation than chemical analysis. Various factors which could explain this anomalous result are discussed.

Biological Assay↗
PubMed1976

A mode of selective action of thiadiazolyl urea herbicides.

1,1-Dimethyl-3-(5-tert-butyl-1,3,4-thiadiazol-2-yl)urea(I) was newly synthesized by the authors. (I) was found to have the strongest herbicidal activities among the thiadiazolylurea derivatives and selectivity of (I) was found between barley (tolerant)and wheat (susceptible) plants. Neither absorption by roots nor translocation from roots to shoots of 35S-labeled (I) in barley and wheat correlated with selectively between these species of plants. (I) was metabolized in both species of plants by N-demethylation to 1-methyl-3-(5-tert-butyl-1,3,4-thiadiazol-2-yl)urea(II), and further to non-phytotoxic 3-(5-tert-butyl-1,3,4-thiadiazol-2-yl)urea(III). The rates of the N-demethylating reactions from (I) to (II) and from (II) to (III) were much greater in barley shoots than in wheat shoots, especially in the second demethylation. It was concluded that the selective activity of (I) between barley and wheat plants was mainly due to the difference in rates of N-demethylation of (I). In addition, it was found that cotton plants, well known as tolerant to phenylurea herbicides, were remarkably susceptible to (I). It was indicated that different rates of the N-demethylating reaction between the phenyl and thiadiazolyl herbicides correlated with susceptibility to them.

Biotransformation↗