Differential toxicity of simazine and diuron to Torilis arvensis and Lolium rigidum

Summary: In a soil application, Torilis arvensis was nearly as susceptible as Lolium rigidum to simazine but was 18-fold more tolerant to diuron. Treat ment with diuron inhibited photosynthesis in L. rigidum but had only a limited effect in T. arvensis although chloroplasts isolated from both species displayed similar susceptibility. 14C-diuron degradation in plants was limited, with the formation of conjugates of mono-methyl-diuron in T. arvensis and N-dealkylated derivatives of diuron in L. rigidum. 14C-diuron entered the roots and was translocated throughout the leaves of L. rigidum but was restricted to stems, leaf petioles and leaf veins of T. arvensis. This difference in transport pat…

Effect of a suicide-substrate of cytochrome P-450 on the metabolism of phenylureas in wheat plants

National audience

Adsorption and activity of atrazine in various soils

Pesticides : interactions phytotoxiques

National audience

Effect of the cytochrome P-450 inactivator 1-aminobenzotriazole on the metabolism of chlortoluron and isoproturon in wheat

Abstract Roots of young wheat plants ( Triticum aestivum cv Clement) were treated with [ 14 C]chlortoluron or [ 14 C]isoproturon alone or mixed with 1-aminobenzotriazole (ABT), a mechanism-based inactivator of cytochrome P -450 monooxygenases. Radioactivity extracted from shoots slightly decreased during periods of metabolism, this decrease being reduced by ABT in the case of isoproturon. ABT strongly inhibited the metabolism of both herbicides. Accumulation of metabolites was generally depressed in the presence of ABT; however, levels of the free N -monodemethylated derivatives were little or not affected. It is concluded that ABT is a synergist of chlortoluron and isoproturon in wheat bec…

Effect of organic matter added to soil on the adsorption of herbicides. Influence of the composition of the organic matter

Effect of mixed function oxidase inhibitors on the toxicite chlortoluron and isoproturon to wheat

International audience

Study of diuron in soil solution by means of a novel simple technique using glass microfibre filters

International audience

Adjuvants : regulatory aspects

International audience

Phytotoxicity and metabolism of chlortoluron in two wheat varieties

Abstract Varietal susceptibility of winter wheat to chlortoluron, 1-(3-chloro-4-methylphenyl)-3,3 dimethylurea, has been studied in two varieties, Corin (susceptible) and Clement (tolerant). After a 24-hr root absorption of the herbicide, phytotoxicity was estimated from growth measurements. When administered at 12 to 96 μM concentrations, the herbicide reduced the growth of both varieties. A significant selective effect was found at 96 μM. Measurements of chlorophyll fluorescence-induction kinetics allowed to discriminate between the two varieties treated with 12 to 48 μM chlortoluron. The metabolism of chlortoluron was studied following absorption of 24 μM solutions. Both varieties produc…

Interaction between diclofop-methyl and 2,4-D in wild oat (Avena fatua L.) and cultivated oat (Avena sativa L.), and fate of diclofop-methyl in cultivated oat

Summary Influence of 2,4-D on toxicity of diclofop-methyl to Avena sativa (cv. Selma) and Arena fatua at 2·5 leaf stage has been evaluated under controlled conditions. Effects of 2,4-D on the fate of diclofop-methyl in cultivated oat have also been studied. Mixture with 2,4-D reduced the toxicity of diclofop-methyl to both species. When applied immediately after diclofop-methyl treatment, 2,4-D still reduced herbicide toxicity to wild oat. This reduction was smaller in cultivated oat. and was only observed at higher phytotoxicity. No interaction was observed when a 10-day period separated the two applications. In mixture, 2,4-D enhanced diclofop-methyl penetration and diclofop acid conjugat…

Use of chlorophyll fluorescence induction kinetics to study translocation and detoxication of DCMU-type herbicides in plant leaves

Transient levels of the fluorescence induction rise were used to quantify partial photosynthesis inhibition by DCMU -type herbicides in whole leaves. Assays in different crop or weed species showed a good accuracy in measurements (generally, variation was lower than 5%). This technique was applied to the problem of varietal selectivity of wheat towards chlortoluron.

Le Columa 1990 : quelles nouvelles molecules

National audience

Les neuf nouveaux herbicides du Columa

National audience

Effet de basses températures sur le devenir du 2,4-D dans le Maïs

National audience

L'absorption foliaire des herbicides

National audience

Diquat, aminotriazole, 2,4-D et glyphosate : quatre types d'herbicides systematiques

National audience

Herbicide foliar absorption and transport in plants

Pourquoi des herbicides perdent-il leur efficacite ?

National audience

Absorption, translocation and metabolism of pyridate in a tolerant crop (Zea mays) and two susceptible weeds (Polygonum lapathifolium L. and Chenopodium album L.)

Summary Absorption, translocation and metabolism of 14C-pyridate were compared in tolerant maize. moderately susceptible Polygonum lapathifolium and susceptible Chenopodium album. Foliar absorption was limited in all species, but comparatively higher penetration levels were observed in younger leaves of dicotyledonous species. The absorbed radioactivity was not very mobile and translocation appeared mainly sym-plastic. Herbicide selectivity could not be explained on the basis of absorption and transport. Chenopodium and P. lapathifolium degraded pyridate and formed unstable water-soluble conjugates that easily released a phytotoxic metabolite. By contrast, more stable unidentified water-sol…

Les nouveaux herbicides

Adsorption et desorption de la terbutryne par une montmorillonite-Ca et des acides humiques seuls ou en melanges

Resume: L' effet du pH sur l'adsorption de la terbutryne par des acides humiques, une montmorillonite-Ca ou leurs melanges montre une certaine similitude de comportement entre ces derniers et l'argile seule. Au voisinage de la neutralite, seuls les acides humiques adsorbent la terbutryne. En milieu acide, les isothermes d'adsorption de la terbutryne par les acides humiques et la montmorillonite sont respectivement de type L et S et traduisent une affinite adsorbat-adsorbant differente; les isothermes d'adsorption correspondant aux melanges ont une forme differente et font apparaitre un effet de synergie, en particulier dans le cas des melanges pauvres en acides humiques. La dsorption saccom…