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1.
Experiments were conducted to examine the up take, translocation and metabolism by S. vulgaris of two distinctly different herbicides: 2,4-D, a phenoxyalkanoic acid with growth regulator activity to which this species exhibits complete tolerance, and chlorsulfuron, a sul-fonylurea to which S. vulgaris is highly sensitive. Despite their structural dissimilarities 2,4-D and chlorsulfuron was readily absorbed by S. vulgaris with 65 and 69%, respectively, of the applied dosage being absorbed within 72 hours after treatment. Approximately 35% of the 2,4-D and 10% of the chlorsulfuron label was translocated out of the treated leaf after 72 hours. Neither herbicide accumulated in the terminal bud. Seventy-two hours after treatment 63% of the recovered 14C remained as unaltered 2,4-D in S. vulgaris, while in tomato, a 2,4-D sensitive species, 65% of the recovered 14C remained as intact herbicide. In S. vulgaris approximately 86% of the radioactivity remained as intact chlorsulfuron 72 hours after treatment compared to 12% in the tolerant wheat. The tolerance of S. vulgaris to 2,4-D could not be accounted for by limited absorption, translocation nor metabolic degradation of the herbicide. The sensitivity of S. vulgaris to chlorsulfuron would appear to be related to the inability of this species to metabolize the herbicide molecule. 相似文献
2.
Lichter Amnon Dvir Orit Ackerman Miryam Feygenberg Oleg Pesis Edna 《Phytoparasitica》2004,32(3):226-236
Litchi fruits are fumigated after harvest with sulfur dioxide (SO2) to prevent their rapid browning. SO2 blocks enzymatic activity but bleaches the fruits and, if this process is followed by dipping the fruit in dilute hydrochloric
acid, the appealing red color is regained. Hot water brushing (HWB) is among the alternative methods that were developed to
replace the use of SO2. HWB reduced fungal population size on the surface of the fruit peel after treatment but did not eliminate fruit infection
after storage. Whereas untreated fruits were infected with a variety of fungal species,Penicillium sp. was the only fungus that developed on the pericarp after storage in fruits that had been dipped in 1.5M HCl. Fruit treated
by HWB followed by handling and storage under sterile conditions suffered greater decay than fruit stored under non-sterile
conditions but with more ventilation. APenicillium sp. isolated from litchi grew well in liquid medium acidified to the pH range reported for SO2 and HCl-treated litchi fruits. Morphological analysis identified fungal isolates asP. aurantiogriseum. Internal transcribed spacer sequence analysis of five isolates suggested a sequence similarity toP. commune. Our data support the hypothesis that dipping litchi fruit in hydrochloric acid eliminates infection by common opportunistic
fungi and selects forPenicillium species that tolerate low pH.
http://www.phytoparasitica.org posting April 30, 2004. 相似文献
3.
Uptake and phytotoxicity of chlorsulfuron in Zea mays L. in the presence of 1,8-naphthalic anhydride
The sites of uptake of chlorsulfuron in maize (Zea mays L.) were investigated at three different growth stages. Exposure of seedling roots, or shoots separately, to herbicide-treated sand over 4 days resulted in inhibition of both roots and shoots. Exposure of seedling roots to chlorsulfuron-treated soil over 21 days severely inhibited both roots and foliage, while separate shoot exposure also reduced both foliage and root growth. After plant emergence, exposure of the crown root node, growing point and lower stem to treated soil reduced foliage and root growth, but exposure of the shoot above the growing point caused only slight inhibition of foliage and had no effect on roots. The herbicide safener 1,8-naphthalic anhydride (NA) applied as a dust (10 g kg?1 seed weight), or as a 50 mg 1?1 suspension in water to maize seeds, reduced the root inhibition by chlorsulfuron in 4-day-old seedlings. NA completely prevented both foliage and root injury when chlorsulfuron was placed in soil in the shoot zone before emergence, or in the shoot zone below the soil surface after plant emergence. NA slightly decreased injury to foliage, but not to roots when chlorsulfuron was placed in soil in the root zone before emergence. NA seed treatment protected both roots and foliage against injury from foliarly applied chlorsulfuron. Plants were also protected when a suspension of NA in water was sprayed on the foliage seven days before chlorsulfuron. When a mixture of NA and chlorsulfuron was applied to foliage, root injury was reduced more than foliage injury. 相似文献
4.
A herbicide bioassay based on tissue cultures of Brassica napus L. was evaluated with selected sulfonylurea herbicides. Data were analysed by fitting the results to a log-logistic dose–response model. Within an experiment, the non-linear regression models were fitted simultaneously to the individual dose–response curves. The results obtained showed good response to even low concentrations of herbicide, with detection limits in the range 0.008–0.69 nmol L?1 for chlorsulfuron and 0.02–0.13 nmol L?1 for metsulfuron. The reproducibility of the assays, on the basis of coefficient of variation of the ED50 values, was found to be 44% for chlorsulfuron and 48% for metsulfuron measurements. Assay of herbicide dissolved in aqueous soil extract showed significant interference from this matrix on the response, requiring a five times dilution of the extract to overcome this matrix effect. 相似文献
5.
A bioassay method using the radicles of pea (Pisum sativum L.) and lupin (Lupinus angustifolius L.) was developed for the assessment of trials on herbicides of common use in the sulfonylurea class (chlorsulfuron, triasulfuron and metsulfuron-methyl) and in the sulfonanylide class (flumetsulam and metosulam). Soils within a range of pH 5.8–8.4 with textures from sand to clay were used in these experiments. The sensitivities of the species were similar in chlorsulfuron and flumetsulam trials and their response range varied with soil type and herbicide, e.g. between 0.75 and 6.0 ng triasulfuron g?1 in the Wimmera grey clay and between 0.125 and 8.0 ng chlorsulfuron g?1 soil in the Mallee sand. The method was demonstrated in a wide range of uses, encompassing tests of the initial bioactivity of formulations of chlorsulfuron and flumetsulam, monitoring the field leaching and persistence of triasulfuron and measuring relative potencies between the classes, using metsulfuron-methyl and metosulam. The bioassay response provided a high level of reproducibility and precision, which was measurable by the logistic curve-fitting procedure. In each case, R2 values were >0.90 and lack-of-fit tests were clearly non-significant at the 0.05 level. Chi-square tests were used to measure differences between ED50's. The method does not require the pre-germination and selection of seedlings, daily watering or root-washing and results are obtained 7 days from sowing, providing favourable use for routine analyses and large-scale trials. 相似文献
6.
The effect of sub-lethal chlorsulfuron treatment of the annual weed Polygonum convolvulus L. on growth and survival of the folivorous beetle Gastrophysa polygoni L. was studied in a controlled environment. Treated and untreated plants were used in whole plant bioassays and in feeding experiments with excised leaves. Direct insect toxicity of the herbicide was studied by use of a Potter Spray Tower. The herbicide was non-toxic to the larvae when applied topically. Larvae fed excised leaves from treated plants did not differ from larvae fed leaves from control plants in terms of developmental time, weight or survival. This suggests that the treatment did not affect the nutritional value of the plant or at least that the beetles could compensate for any such changes. Chlorsulfuron reduced survival of larvae living on whole plants treated with sub-lethal dosages (8 to 67% of the recommended field rate). The mortality of larvae in whole plant experiments was dependent on herbicide dosage and herbivore load. Mortality ranged from approximately 20% on control plants to a maximum of 80% on plants sustaining the highest dosages and herbivore loads. It is argued that the beetles' response to chlorsulfuron-treated plants could be caused by a herbivore-induced plant response enhanced by the action of chlorsulfuron. 相似文献
7.
M. ANDREWS 《Weed Research》1990,30(5):331-340
Avena saliva cv. Amuri and A. fatua were sprayed with diclofop methyl (1.0 kg a.i. ha?1) alone and in combination with 2,4-D (1.1 kg a.i. ha?1), bentazone (1.0 kg a.i. ha?1), chlorsulfuron (15 g a.i. ha?1) or dicamba (0.3 kg a.i. ha?1). Effects of the herbicides on leaf extension rate during the first 8 to 10 days after spraying and subsequent growth (dry weight) after 57–75 days were determined by comparison with unsprayed plants. Diclofop-methyl applied alone did not cause a decrease in leaf extension rate of A. saliva or A. fatua until at least 4 days after spraying. All broadleaf weed herbicides in combination with diclofop-methyl caused a decrease in leaf extension rate of both species within 2 days of spraying. Ten days after spraying, leaf extension rates for plants sprayed with a broadleaf weed herbicide plus diclofopmethyl (all combinations) were lower than for unsprayed plants but greater than for plants sprayed with diclofop-methyl alone. With the exception of A. fatua sprayed with bentazone, long-term growth of plants sprayed with a broadleaf weed herbicide plus diclofop-methyl (all combinations) was lower than for unsprayed plants but greater than for plants sprayed with diclofop-methyl alone. Bentazone applied with diclofop-methyl caused a substantial decrease in leaf extension rate of A. fatua within 24 h of spraying but at harvest, dry weight of plants from this treatment was similar to or less than that for plants sprayed with diclofop-methyl alone. Application of diclofop-methyl with bentazone at a rate of 0.3 kg a.i. ha?1 also caused a reduction in leaf extension rate of A. fatua within one day of spraying. At this rate of bentazone, dry weight of plants at harvest was intermediate to that of unsprayed plants and those sprayed with diclofop-methyl alone. It is proposed that decreased leaf expansion rate during the first few days afte spraying is the cause of broadleaf weed herbicide antagonism of diclofop-methyl. 相似文献
8.
Differences were observed in the sensitivity of three wheat (Triticum aestivum L.) cultivars to chlorsulfuron. Shoot dry weight was reduced by foliar applications of chlorsulfuron to a greater extent in cv. Rongotea than in cvs Lancer and Kotare. There was no difference between these cultivars in the specific activity of acetolactate synthase (ALS) enzyme extracted from leaves or roots. Moreover, chlorsulfuron inhibited ALS from the wheat cultivars to the same extent in?vitro. ALS measurement in vivo showed that after 15 h of incubating excised leaf tissues with chlorsulfuron, there was a greater reduction in ALS enzyme activity in Rongotea than in the other cultivars. Furthermore, 1 day after a foliar application of chlorsulfuron, in vitro ALS activity in leaves was reduced more in Rongotea than in Lancer or Kotare. Recovery of the enzyme activity following chlorsulfuron application was quicker in Kotare than in Lancer or Rongotea. It is concluded that differences in sensitivity of these wheat cultivars to chlorsulfuron are not due to differential ALS sensitivity or level, but may be due to differential rates of herbicide metabolism. 相似文献
9.
H.H. Hoppe A. Kerkenaar A. Kaars Sijpesteijn 《Pesticide biochemistry and physiology》1976,6(5):413-421
3-Phenylindole is an antimicrobial compound active towards many fungi and gram-positive bacteria. At 5 μg/ml it inhibits growth of Aspergillus niger. Higher concentrations (50 μg/ml) also suppress spore germination; they do not kill the fungus. Dry weight of the fungus still increases for 1 or 2 days after fungicide treatment. The toxicant has no effect on O2 uptake even at higher concentrations (100 μg/ml). The compound markedly affects composition of the lipid fraction of A. niger inducing a decrease in phospholipid concentration with a coincident increase in free fatty acids. Sterol pattern and sterol concentration were not affected. Antifungal activity was reversed by phospholipids added to the medium. 3-Phenylindole induced a slight leakage of 32P-labeled compounds from the treated cells under growth conditions but not under nongrowth conditions. A strain of A. niger resistant to 3-phenylindole had the same phospholipid and sterol pattern as the wild type, but the level of both components was higher (40–60%). The 3-phenylindole-resistant strain showed resistance to triarimol and pimaricin. The wild type and the resistant strain both took up 3-phenylindole quite rapidly and accumulated it in the mycelium. 3-Phenylindole possibly interferes with phospholipid function in cell membranes, although the specific site of action has not yet been elucidated. 相似文献
10.
11.
Sulfonylurea resistance in Stellaria media [L.] Vill. 总被引：1，自引：1，他引：1
A sulfonylurea resistant biotype of common chickweed (Stellaria media L. Vill.) was found in a field treated with chlorsulfuron or metsulfuron for eight consecutive years. In pot experiments the biotype was resistant to postemergence treatments with the following acetolactate synthase (ALS) inhibitors: chlorsulfuron, metsulfuron, tribenuron, triasulfuron, rimsulfuron, sulfometuron, flumetsulam and imazapyr. The level of resistance to chlorsulfuron and sulfometuron was higher than to the other sulfonylurea herbicides. Whereas the level of cross resistance to the triazolopyrimidine herbicide, flumetsulam was comparable to that of metsulfuron, that of imazapyr was significantly lower. In contrast to imazapyr the biotype was not resistant to imazethapyr, an other imidazolinone herbicide. ALS in vitro assays revealed that resistance was due to an ALS enzyme that was less sensitive to ALS inhibiting herbicides. Herbicides with different modes of action were equally effective on the susceptible and resistant biotypes. 相似文献
12.
Abstract A bacterium designated Tr A and capable of decomposing trifluralin in the presence of glutamate, lactate, acetate and yeast extract was isolated. Optimum pH for growth of this organism was 6.5 in a glutamate medium containing 0.01% trifluralin. Maximum decomposition of the herbicide occurred at pH 7.4 A threshold concentration of 0.05% trifluralin was necessary for the growth of this organism. Ninety-five per cent of the trifluralin was decomposed within 21 days in an 0.01% trifluralin medium, but none was degraded at a concentration of 0.05%. The herbicide remained stable for 10 days in an aqueous solution at different pH levels. 相似文献
13.
Harry J. Strek 《Pest management science》1998,53(1):29-51
The behaviour and fate of chlorsulfuron in aqueous and soil systems were examined in laboratory studies. Aqueous hydrolysis was pH-dependent and followed pseudo-first-order degradation kinetics at 25°C, with faster hydrolysis occurring at pH 5 (half-life 24 days) than at either pH 7 or 9 (half-lives >365 days). Degradation occurred primarily by cleavage of the sulfonylurea bridge to form the major metabolites chlorobenzenesulfonamide (2-chlorobenzenesulfonamide) and triazine amine (4-methoxy-6-methyl-1,3,5-triazin-2-amine). This route is a major degradation pathway in water and soil systems. Aqueous photolysis (corrected for hydrolysis) proceeded much more slowly (half-life 198 days) than aqueous hydrolysis and is not expected to contribute significantly to overall degradation. Hydrolysis in soil thin-layer plates exposed to light (half-life 80 days), however, progressed at a much faster rate than in dark controls (half life 130 days), which suggests that a mechanism other than direct photolysis may have been operative. An aerobic soil metabolism study (25°C) in a Keyport silt loam soil (pH 6·4, 2·8% OM) showed that degradation was rapid (half-life 20 days). Dissipation in an anaerobic sediment/water system (initial pH of water phase 6·7, final pH 7·4) progressed much more slowly (half-life >365 days) than in aerobic soil systems. Major degradation products in aerobic soil included the chlorobenzenesulfonamide and triazine amine as in the aqueous hydrolysis study. Neither of these degradation products exhibited phytotoxicity to a variety of crop and weed species in a glasshouse experiment, and both exhibited an acute toxicological profile similar to that of chlorsulfuron in a battery of standard tests. Demethylation of the 4-methoxy group on the triazine moiety and subsequent cleavage of the triazine ring is another pathway found in both aqueous solution and soils, though different bonds on the triazine amine appear to be cleaved in the two systems. Hydroxylation of the benzenesulfonamide moiety is a minor degradation pathway found in soils. Two soils amended with 0·1 and 1·0 mg kg-1 chlorsulfuron showed slight stimulation of nitrification. The 1·0 mg kg-1 concentration of chlorsulfuron resulted in minor stimulation and inhibition of 14C-cellulose and 14C-protein degradation, respectively, in the same soils. Batch equilibrium adsorption studies conducted on four soils showed that adsorption was low in this system (Koc 13–54). Soil thin-layer chromatography of chlorsulfuron (Rf=0·55–0·86) and its major degradation products demonstrated that the chlorobenzenesulfonamide (Rf=0·34–0·68) had slightly less mobility and that the triazine amine (Rf=0·035–0·40) was much less mobile than chlorsulfuron. In an aged column leaching study, subsamples of a Fallsington sandy loam (pHwater 5·6, OM 1·4%) or a Flanagan silt loam (pHwater 6·4, OM 4·0%) were treated with chlorsulfuron, aged moist for 30 days in a glasshouse and then placed upon a prewet column of the same soil type prior to initiation of leaching. This treatment resulted in the retention of much more total radioactivity (including degradation products) than by a prewet column, where initiation of leaching began immediately after chlorsulfuron application, without aging (primarily chlorsulfuron parent). © 1998 SCI 相似文献
14.
The response of natural and planted stands of Allium vineale L. to chlorsulfuron and metsulfuron was determined in field experiments in Illinois, U.S.A., in 1982 and 1983. In natural stands very low rates of either herbicide controlled A. vineale. Chlorsulfuron, applied in the spring at 20 g ha?1, reduced aerial bulblet production by 99% but when it was applied in the fall it reduced aerial bulblet production by only 59%. All rates of metsulfuron (5–20 g ha?1), at both times of application, effected better than 94% reduction in plant density and yield of aerial bulblets. In a glasshouse experiment, plants derived from aerial bulblets were more susceptible to chlorsulfuron than plants derived from soft offset bulbs. Soft offset bulbs were, therefore, used to establish a uniform stand of A. vineale in the field. In this experiment, non-linear regression analysis showed that metsulfuron was two to three times more active than chlorsulfuron. GR95 values calculated from the computed regression equations show that metsulfuron and chlorsulfuron, applied in April at 5 and 15 g ha?1, respectively, reduced aerial and underground bulb production by 95%. 相似文献
15.
Measurement of the root lengths of pre-ger-minated oat seedlings (Avena sativa L. var. Sioux) grown in the dark in treated soils was used to assay residues of diclofop acid (2-[4-(2,4-dichloro-phenoxy)phenoxy]propionate) and sethoxydim (2-[1-(ethoxyimino)-butyl]-5-[2-(ethylthio)-propy]-3-hydroxy-2-cyclohexene-1-one). Similar measurements involving maize seedlings (Zea Mays L. var. Sunny Vee) were also used to determine residues of the herbicide chlorsulfuron (2-chloro-N-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)aminocarbony]benzenesulfonamide) in soils. The procedure appeared to be reproducible with residues of chlorsulfuron, diclofop acid and sethoxydim being detectable at amounts of 0.001, 0.2 and 0.05 μg g?1 respectively. 相似文献
16.
Lars Bergstrm 《Pest management science》1996,48(1):37-45
Model simulations of chlorsulfuron (1-(2-chlorophenylsulfonyl)-3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)urea) leaching in a loamy soil were made with the mechanistic dual-porosity model MACRO. Comparisons were made with a data set obtained in a lysimeter experiment in which leaching was measured during an 11-month period after applying chlorsulfuron at two rates (4 and 8 g ha−1). In this experiment, peak concentrations appeared c.6 months after pesticide application, reaching levels of 14 and 21 ng litre−1 in the low- and high-dose treatments, respectively. These peak concentrations appeared after c.70 mm of accumulated leachate, implying that some of the herbicide was displaced through the soil columns by non-equilibrium flow processes. Model calibration was limited to parameters related to evapotranspiration, water uptake by roots and degradation rates in the subsoil. With this minimum amount of calibration, the model successfully described the leaching pattern of chlorsulfuron, provided that the two-flow domain option in the model was used. Running the model in one-flow domain resulted in considerable underestimates of leaching of chlorsulfuron over the short-term (<1 year). The degradation rate in the subsoil was also found to be critical. It had to be increased about fivefold to match measured chlorsulfuron concentrations in leachate. At such concentrations, 0·012 g ha−1 of chlorsulfuron (0·3% of that applied) was predicted to leach through the soil profile during the 11-month simulation period when the lower dose of the compound was applied. 相似文献
17.
Wheat (Triticum aestivum L.) cultivars showed differential tolerance to chlorsulfuron. Cultivar Kotare showed no injury symptoms following foliar applications of chlorsulfuron at 15 or 60 g a.i. ha?1, while cultivars Rongotea and Lancer showed early damage in pot and field experiments at both rates of chlorsulfuron. Cultivars Abele and Jasper were intermediate in their response. The number of spikelets per ear was the only yield component affected by chlorsulfuron and was reduced in Lancer and Rongotea. Retention, uptake and transiocation of chlorsulfuron were not different between Kotare and Ron-gotea. Within 48 h of application, Kotare metabolized 92–2% of [14C]chlorsulfuron, while Lancer and Rongotea metabolized only 43–5% and 63% of the herbicide, respectively. The concentration of chlorsulfuron in young tissues of Kotare, Lancer and Rongotea, 48 h after application was calculated as 1.2, 31.9 and 15.6 ng g?1 dry weight, respectively. It is concluded that differential rates of metabolism are the main reason for differences in sensitivity to chlorsulfuron between the wheat cultivars tested. Le mécanisme des différences de tolérance au chlorsulfuron entre variétés de blé Des variétés de blé (Triticum aestivum L.) ont montré des différences de tolérance au chlorsul-furon. On n'a aucun symptôme de phytotoxicité sur la variété‘Kotare’ après une application foliaire de chlorsulfuron à 15 ou 60 g m.a. ha?1, alors que les variétés ‘Rongotea’ et ‘Lancer’ présentaient des symptômes précoces aux deux doses, dans des expériences en pot et au champ. La réponse des variété‘Abele’ et ‘Jasper’était intermédiaire. Le nombre de grains par épillet était la seule composante du rendement affectée parle chlorsulfuron et était réduit chez Lancer et Rongotea. La rétention, la pénétration et la migration de chlorsulfuron n'était pas différentes entre Kotare et Rongotea. Quarante huit heures après le traitement, Kotare avait metabolise 92,2% du [14C]chlorsulfuron, alors que Lancer et Rongotea ne métabolisaient que respectivement 43,5 et 63% de l'herbicide. La concentration de chlorsulfuron dans les tissus jeunes de Kotare, Lancer et Rongotea 48 h après la traitement a étéévaluée à respectivement 1,2,31,9 et 15,6 ng g?1 de matière sèche. Il est conclu que des différences de vitesse de métabolisation sont la raison principale des différences de sensibilité au chlorsulfuron observées chez les variétés de blé testées. Mechanismen der unterschiedlichen Reaktion von Weizensorten auf Chlorsulfuron-Behandlun-gen Es wurde eine unterschiedliche Toleranz bei Weizensorten (Triticum aestivum L.) gegenüber Chlorsulfuron-Behandlungen beobachtet. Bei der Sorte ‘Kotare’ traten nach Behandlungen mit 15 oder 60 g AS ha keine Schadsymtome auf, während die Sorten ‘Rongotea’ und ‘Lancer’ sowohl in Topfals auch in Freilandversuchen bei beiden Dosen frühe Schädigungen erlitten; die Sorten ‘Abel’ und ‘Jasper’ reagierten mittelstark. Unter den Ertragskomponenten war nur die Zahl der Ährchen pro Ähre betroffen, sie war bei ‘Lancer’ und ‘Rongotea’ reduziert. Aufnahme und Translokation des Wirkstoffs waren bei ‘Kotare’ und ‘Rongotea’ gleich. Bei ‘Kotare’ war [14C]Chlorsulfuron 48 h nach der Applikation zu 92,2 % metabolisiert, bei ‘Rongotea’ zu 63 % und bei ‘Lancer’ zu 43,5 %. In jungen Geweben dieser Sorten lagen die Chlor-sulfuron-Konzentrationen 48 h nach der Anwendung bei 1,2, 15,6 und 31,9 ng g?1 TM. Die unterschiedlichen Metabolisierungsraten bei den untersuchten Weizensorten wurden für den Hauptgrund für die Toleranzunterschiede gegenüber Chlorsulfuron gehalten. 相似文献
18.
Acetolactate synthase (ALS) from one susceptible and two chlorsulfuronresistant biotypes of Stellaria media(L.) Vill. was assayed in the presence of eight known ALS inhibitors. As expected, ALS from the chlorsulfuronresistant biotypes (R1 and R2) showed reduced sensitivity to chlorsulfuron and other sulfonylurea herbicides. The patterns of cross-resistance varied, however, indicating that the alteration in ALS that confers chlorsulfuron resistance does not confer the same level of resistance to other sulfonylurea herbicides. The resistant biotypes were highly cross-resistant to sulfometuron-methyl and DPX-A7H81, but less cross-resistant to triasulfuron. Both R1 and R2 were highly cross-resistant to DTPS (N-[2,6-dichlorophenyl]-5,7-dimethyl-1,2,4-iriazolo[1,5a]pyrimidine-2-siilfoiiamide), but only slightly cross-resistant to imazamethahenz, an imidazolinone herbicide. The differences in the patterns of cross-resistance observed presumably reflect differences in the binding affinity of the herbicides for the altered ALS. The data presented suggest, but do not confirm, that R1 and R2 contain the same ALS mutation. 相似文献
19.
BACKGROUND: Lolium rigidum Gaud. is one of the most common weed species in winter cereals in north‐eastern Spain, with populations that have evolved resistance to herbicides becoming more widespread since the mid‐1990s. Nine trials on commercial fields with herbicide‐resistant L. rigidum were conducted during the cropping seasons 2001–2002 to 2003–2004, testing the efficacy of 20 herbicides and mixtures pre‐ and post‐emergence and as sequential applications. Weed populations chosen had different resistance patterns to chlortoluron, chlorsulfuron, diclofop‐methyl and tralkoxydim, representative of the resistance problems faced by farmers. RESULTS: In pre‐emergence, prosulfocarb mixed with trifluralin, chlortoluron or triasulfuron was effective on six populations. In post‐emergence, iodosulfuron alone or mixed with mesosulfuron gave the best results but did not control three resistant populations. At Ferran 1, none of the herbicide combinations reached 90% efficacy. CONCLUSIONS: The diverse efficacy patterns of the different populations demonstrate the need for detailed knowledge of the populations before using herbicides. Moreover, the unexpected insufficient efficacy of the new herbicide iodosulfuron prior to its field use shows the need to combine herbicides with other non‐chemical weed control methods to control resistant L. rigidum in north‐eastern Spain. Copyright © 2010 Society of Chemical Industry 相似文献
20.
P. R. Stork 《Weed Research》1997,37(1):19-26
A controlled–release formulation of chlorsulfuron (DT26B) and a conventional granular formulation were compared for their initial bioefficacy and leaching in laboratory and field experiments. Three alkaline soil types, representative of farm soils in SE Australia, were used for these experiments. Laboratory tests of initial bioefficacy using a Mallee sand (pH 7.2) were able to detect, within ED05–95 limits, that approximately 50% of active ingredient remained as a non–available reserve in DT26B immediately after spraying, when compared with the granular formation. There was also an indication that the bioavailable component of active ingredient in DT26B would be sufficient for weed control. This was confirmed at field sites on a Kattyoong sand (pH 7.9) and a Wimmera Grey clay (pH 8.4), after using recommended application rates of chlorsulfuron during the 1994 winter growing season. The formulations produced only marginal differences in control of Lolium rigidum Gaud. The field leaching trials at these sites showed that there can be rapid leaching of chlorsulfuron with only small amounts of rainfall. Under these conditions, there was an overall trend of reduced leaching by DT26B at both trial sites, although these reductions were not significant when compared with the granular formation, A laboratory system designed to measure the mobility of herbicides is described. It was used to impose upon each formulation a greater level of leaching than in the field trials, using Mallee sand columns irrigated with 50 mm day–1 under –50 kPa suction. This test revealed a negligible reduction in leaching of chlorsulfuron by DT26B as compared with the granular formulation. Therefore, although the controlled–release formulation DT26B demonstrated that it could provide a viable alternative for weed control under conventional spraying conditions in arable farming, the agricultural usage of DT26B for the purpose of reducing leaching could not be warranted at its current stage of development. 相似文献