Used Fungicides (used + fungicide)

Distribution by Scientific Domains

Selected Abstracts

High-performance liquid chromatographic/tandem mass spectrometric identification of the phototransformation products of tebuconazole on titanium dioxide

Paola Calza
Abstract Tebuconazole is a widely used fungicide. The formation of by-products on irradiated titanium dioxide as a photocatalyst was evaluated. Several species derived from tebuconazole degradation were identified and characterized by HPLC/MSn. A pattern of reactions accounting for the observed intermediates is proposed. Different parallel pathways are operating (and through these pathways the transformation of the molecule proceeds), leading to a wide range of intermediate compounds. All these molecules are more hydrophylic than tebuconazole. The main steps involved are (1) the hydroxylation of the molecule with the formation of three species having [M + H]+ 324; the hydroxylation occurs on the C-1 carbon and on the aromatic ring in the two ortho -positions; (2) the cleavage of a C,C bond with the release of the tert -butyl moiety and the formation of a species having m/z 250; analogously to step 1, also on this species a further hydroxylation reaction occurs; (3) through the loss of the triazole moiety with the formation of a structure with m/z 257. Copyright 2002 John Wiley & Sons, Ltd. [source]

Variation of Fungicide Resistance in Czech Populations of Pseudoperonospora cubensis

J. Urban
Abstract During the growing seasons between the years 2001 and 2004, 98 isolates of Pseudoperonospora cubensis from nine regions of Czech Republic were collected and screened for tolerance/resistance to the three frequently used fungicides (propamocarb, fosetyl-Al, metalaxyl). Fungicides were tested in five different concentrations, using a floating disc bioassay. Fungicide effectiveness varied considerably. Propamocarb appeared most effective and all the isolates collected in the years 2001,2003 were found sensitive to all tested concentrations [607,9712 ,g active ingredient (a.i.)/ml]. In 2004, some strains with increased resistance to propamocarb were detected. These strains were characterized by tolerance at the lowest concentrations (607 ,g a.i./ml, eventually on 1214 ,g a.i./ml); however, they were controlled by 2428 ,g a.i./ml. Fosetyl-Al was effective at the recommended concentration of 1600 ,g a.i./ml against all isolates. However, the occurrence of isolates (collected in 2001) which sporulated at low concentrations (400 and 800 ,g a.i./ml) indicated that the selection for tolerance occurs in the pathogen population. Nevertheless, this phenomenon was not confirmed with the P. cubensis isolates collected between the years 2002 and 2004. Metalaxyl was found ineffective, because 97% of the isolates showed the resistance to the recommended concentration (200 ,g a.i./ml), and the other 3% of isolates expressed tolerant response. The majority of the isolates showed profuse and/or limited sporulation at higher concentrations (400 and 800 ,g a.i./ml). A substantial shift to highly metalaxyl resistant strains was evident in the Czech P. cubensis populations during 2001,2004. [source]

Evaluation of aqueous Moringa seed extract as a seed treatment biofungicide for groundnuts

Patricia O Donli
Abstract In a search for alternatives to currently used fungicides, the potential of aqueous Moringa seed extract (AMSE) as a seed treatment was evaluated. Seeds of groundnut, Arachis hypogea L cv Dakar, were soaked in AMSE at concentrations of 1, 5, 10, 15 and 20,g,litre,1 for 24,h. Comparison was made with Apron Plus (metalaxyl,+,carboxin,+,furathiocarb), until recently a recommended seed-treatment chemical, and distilled water, which was the medium for extraction of Moringa seeds. The results showed that AMSE has potential for use as a biofungicide on groundnut seeds, since all the concentrations used except 1,g,litre,1 brought about significant reduction in the incidence of fungi on the seeds, such reduction increasing as the dosage of AMSE increased. There were no significant differences in control between the highest concentration of AMSE (20,g,litre,1) and Apron Plus at the manufacturer's recommended level. Water also produced slight reductions in the incidence of fungi, although this was not significant at P,=,0.05. The sensitivity to AMSE of the fungi tested varied, Mucor sp being the most sensitive and Aspergillus niger the least, with Rhizopus stolonifer and Aspergillus flavus intermediate. 2003 Society of Chemical Industry [source]

Environmental fate of metalaxyl and chlorothalonil applied to a bentgrass putting green under southern California climatic conditions

L Wu
Abstract Putting greens usually receive high inputs of fertilizers and pesticides to meet the high demand for visual quality and to overcome the stress from close mowing and traffic. In this study, two commonly used fungicides, metalaxyl (methyl N -(methoxyacetyl)- N -(2,6-xylyl)- DL -alaninate) and chlorothalonil (2,4,5,6-tetrachloro-1,3-benzenedicarbonitrile), were evaluated for their partitioning and persistence in a bentgrass (Agrostis palustris Huds) putting green under southern California climatic conditions. The putting green site was constructed according to the US Golf Association (USGA) specifications. Lysimeter assemblies installed at the center of each plot were used to monitor the leachate, flux chambers were used to measure volatilization, clippings were collected to determine the residues on grass, and soil cores were sampled to determine residues in the soil profile. Results showed that cumulative volatilization loss accounted for 0.10 and 0.02%, clipping removal 0.11 and 0.13%, and cumulative leaching 0.71 and 0.002% of the applied metalaxyl and chlorothalonil, respectively. The two fungicides were mainly found in the top 10,cm of the soil profile due to the high organic carbon content in the thatch and mat layers. The dissipation half-life was 1.4 days for metalaxyl and 4.9 days for chlorothalonil on grass, shorter than those found in agricultural fields. This study showed that, under normal turf management practices, the offsite transport of the parent fungicides was minimal. Future research should focus on investigating the fate and mobility of the metabolites of the fungicides. 2002 Society of Chemical Industry [source]