光敏型氯磺隆与普通氯磺隆的控草效果比较

比较了光敏型氯磺隆与普通氯磺隆不同剂量对各种杂草的控制效果。结果显示在低剂量下,普通氯磺隆的控草效果略高于光敏型氯磺隆。在中量、高量和倍量下,两种制剂控草效果差异不大。     

Controlled release of isoproturon from an alginate–bentonite formulation: water release kinetics and soil mobility

The herbicide isoproturon [3‐(4‐isopropylphenyl)‐1,1‐dimethylurea] was incorporated in alginate‐based granules to obtain controlled‐release (CR) properties. The basic formulation (sodium alginate (1.87%)–isoproturon (0.67%) in water) was modified by addition of different sorbents. The effect on isoproturon release rate, modified by the incorporation of natural and acid‐treated bentonite in alginate formulation, was studied by immersion of the granules in water while shaking. The release of isoproturon was diffusion‐controlled. The time taken for 50% of the active ingredient to be released into water, T₅₀, was longer for those formulations containing added bentonite (5.98 and 7.43 days, for natural and acid‐treated (1 M H₂SO₄) bentonite, respectively) than for the preparation without bentonite (3.78 days). The mobilities of non‐formulated technical grade (98%) and formulated isoproturon were compared using soil columns. The use of alginate‐based CR formulations containing bentonite reduced isoproturon movement compared with the technical product. Sorption capacity of the soil for isoproturon was measured using batch experiments (0.29 litre kg⁻¹) and the results obtained here in agreement with those obtained under dynamic conditions. © 2000 Society of Chemical Industry     

The release of cyanatryn from a controlled-release formulation into flowing water

The problem of maintaining a sufficient concentration of the herbicide cyanatryn in flowing water for a sufficient time to control aquatic weeds has been solved by using a controlled-release pellet formulation. The rate of release of the herbicide depends primarily on the rate of diffusion within the clay matrix and is a function of the formulation ingredients and the degree of compaction achieved during manufacture. Release appears to be independent of water velocity but the concentration produced downstream of the application point depends on the volume of water flowing in unit time and the mass of herbicide used.     

Degradation of the sulfonylurea herbicides chlorsulfuron and triasulfuron in a high-organic-matter volcanic soil

The degradation rates of two sulfonylurea herbicides, chlorsulfuron and triasulfuron, were determined at two application rates, 15 and 30 g a.i. ha^–1, in a sandy loam soil of volcanic origin under controlled environment and field conditions. Residues were measured using a modified gas chromatographic (gc) determination method. Both herbicides degraded rapidly in the acidic soil (pH 5.7) with high organic matter levels (7.3% o.m.), generally according to first-order rate kinetics. The respective half-lives ranged from 22 to 38 d for chlorsulfuron and from 31 to 44 d for triasulfuron under five controlled temperature/soil moisture regimens, ranging from 10 to 30 °C and between 40% and 80% maximum water-holding capacity. Half-lives in the field were considerably shorter (13 d for chlorsulfuron and 12–13 d for triasulfuron). The degradation rates of the herbicides were influenced more by soil temperature than by soil moisture content. Bioassays using white mustard ( Sinapis alba L.) and forage sorghum [ Sorghum bicolor (L.) Moench] were also used to determine the persistence of phytotoxic residues of both herbicides in the field, and the results showed that the effects of chlorsulfuron disappeared within 8 weeks. Triasulfuron residues disappeared within 9 and 14 weeks for the 15 and 30 g a.i. ha^–1 rates respectively.     

Plant sensitivity to atrazine and chlorsulfuron residues in a soil-free system

The sensitivity of 22 major crops, pastures and weeds from the north-east grain region of Australia to atrazine and chlorsulfuron residues was determined in a glasshouse using a soil-free bioassay system. A logistic equation was fitted to the seedling fresh weights as a function of the logarithm of herbicide concentration by non-linear regression and used to calculate the doses for 10%, 30% and 50% inhibition of seedling growth (ID₁₀, ID₃₀ and ID₅₀). The ID₅₀ for atrazine ranged from 0.03 to 0.04 mg a.i. L^–1 for Salvia reflexa Hornem. and barley to 1.47 mg a.i. L^–1 for sorghum. The ID₅₀ for chlorsulfuron ranged from 0.19 to 0.21 μg a.i. L^–1 for lucerne and snail medic to 102 μg a.i. L^–1 for wheat. Based on ID₅₀ values measured, the predicted responses of each species to a range of concentrations of atrazine and chlorsulfuron were classified into four categories ranging from no damage to severe damage. These sensitivity data will assist in planning cropping sequences in soils previously treated with atrazine or chlorsulfuron.     

Photolysis of chlorsulfuron and metsulfuron-methyl in methanol

Photolysis of chlorsulfuron and metsulfuron-methyl was studied in methanol under UV light. Their rates of primary photolysis followed first-order kinetics. The main photoproducts were identified as 2-methoxy-4-methyl-1,3,5-triazin-6-amine, 2-chloro-benzenesulfonamide and methyl 2-(aminosulfonyl)benzoate, which entailed the cleavage of the two N–C ureic bonds. Further photolysis of benzenesulfonamide derivatives involved oxidation of −NH₂, cyclisation with loss of CH₃OH, and scission of the C–S bond A trace of methyl o-mercaptobenzoate was also detected. The corresponding photolysis pathways of chlorsulfuron and metsulfuron-methyl were tentatively proposed. © 1999 Society of Chemical Industry     

Kinetics and hydrolysis mechanism of chlorsulfuron and metsulfuron-methyl

In acidic media, hydrolysis of chlorsulfuron and metsulfuron-methyl occurs via two consecutive reactions which were followed by ultraviolet spectrophotometry. For these two reactions, the pseudo-first-order rate constants increase proportionally to the concentration of hydronium ion in the more acidic media and to the square of this concentration at higher pH values. A kinetic study by HPLC shows that the first reaction leads to the formation of 4-methoxy-6-methyl-1,3,5-triazin-2-amine and (o-chlorophenylsulfonyl) carbamic acid for chlorsulfuron or (o-methoxycarbonylphenylsulfonyl) carbamic acid for metsulfuronmethyl. The second reaction is the conversion of these sulfonylcarbamic acids to sulfonamides and carbon dioxide. The complete lack of saccharin and of o-sulfamoyl benzoic acid proves that the ester function of the methoxycarbonyl group is stable. The lack of general acid-base catalysis and a solvent deuterium isotope effect less than unity are consistent with a rate-determining cleavage of the protonated substrate. In the basic pH range (10–14) a single reaction occurs, the nucleophilic substitution of the methoxy group on the triazine by a hydroxide group.     

羧甲基壳聚糖/改性膨润土复合载体对莠去津释放和淋溶的影响

首次尝试将羧甲基壳聚糖与改性膨润土复合用作除草剂莠去津的载体,制备得到控释型颗粒剂,以延缓莠去津的释放,减少淋溶损失,提高药效及控制其污染。通过水中释放实验研究了制剂配方对莠去津释放速率的影响,并借助半经验方程探讨了其释放机理,采用土壤薄层实验考察了复合载体对降低莠去津淋溶的效果。 结果表明,采用复合载体时莠去津的半数释放时间(t 50)可达700 h 以上,比对照采用单一羧甲基壳聚糖作载体时延长了1倍以上。莠去津由颗粒剂向水相释放的过程主要受费克扩散(Fickian diffusion)控制,且经9次淋洗后莠去津的累计淋出率仅为6.0%,表明该复合载体控释制剂可显著减少莠去津对地下水的污染。     

Hydrolysis of triasulfuron,metsulfuron‐methyl and chlorsulfuron in alkaline soil and aqueous solutions

The hydrolysis of triasulfuron, metsulfuron‐methyl and chlorsulfuron in aqueous buffer solutions and in soil suspensions at pH values ranging from 5.2 to 11.2 was investigated. Hydrolysis of all three compounds in both aqueous buffer and soil suspensions was highly pH‐sensitive. The rate of hydrolysis was much faster in the acidic pH range (5.2–6.2) than under neutral and moderately alkaline conditions (8.2–9.4), but it increased rapidly as the pH exceeded 10.2. All three compounds degraded faster at pH 5.2 than at pH 11.2. Hydrolysis rates of all three compounds could be described well with pseudo‐first‐order kinetics. There were no significant differences (P = 0.05) in the rate constants (k, day⁻¹) of the three compounds in soil suspensions from those in buffer solutions within the pH ranges studied. A functional relationship based on the propensity of nonionic and anionic species of the herbicides to hydrolyse was used to describe the dependence of the ‘rate constant’ on pH. The hydrolysis involving attack by neutral water was at least 100‐fold faster when the sulfonylurea herbicides were undissociated (acidic conditions) than when they were present as the anion at near neutral pH. In aqueous buffer solution at pH > 11, a prominent degradation pathway involved O‐demethylation of metsulfuron‐methyl to yield a highly polar degradate, and hydrolytic opening of the triazine ring. It is concluded that these herbicides are not likely to degrade substantially through hydrolysis in most agricultural alkaline soils. © 2000 Society of Chemical Industry     

Aspergillus niger and a Penicillium sp. are not directly involved in the degradation of chlorsulfuron

When Aspergillus niger or a Penicillium sp. were grown in potato dextrose broth supplemented with chlorsulfuron, the herbicide concentration decreased by 97–99% within 78–96 h and the pH of the medium fell from 7.2 to between 2.4 and 3.1. If, during growth, the pH was maintained at or near neutrality, no decrease in herbicide concentration occurred. When sterile medium containing the herbicide was titrated with acid to mimic acid formation during fungal growth, the herbicide concentration again declined. Precipitation was not responsible for the observed decrease. The data indicate that, in laboratory media, these fungi do not directly metabolise the herbicide as previously thought. Chlorsulfuron degradation in perfused soil cores was not enhanced by inoculation with A. niger. Our results show that A. niger and a Penicillium sp. do not degrade chlorsulfuron.     

Acetolactate synthase activity and chlorsulfuron sensitivity of wheat cultivars

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.     

粉锈宁缓释剂防治玉米丝黑穗病

玉米丝黑穗病是贵州省玉米的主要病害之一,每年都造成严重损失。按常规使用0.08％粉锈宁农药直接拌干玉米种防治此病,防效差,易产生药害。将粉锈宁与聚乙烯醇等复配成缓释剂后拌萌动的玉米种,解决了药害问题,还提高了防效。     

Phytotoxicity and persistence of chlorsulfuron as affected by activated charcoal

Two bioassay procedures, using petri-dishes and pots, based on the root growth of pregerminated maize were used to study the residual phytotoxicity of chlorsulfuron under field conditions. Both bioassay procedures appeared to be equally reproducible and sensitive with residues of chlorsulfuron being detectable from 0·25 to 10·0 ng g^-1. The results indicated that persistence, movement and phytotoxicity increased with increasing rate of chlorsulfuron, but persistence of the herbicide was shorter in wet compared to dry field conditions. As little as 1 g a.i. ha^-1 of incorporated chlorsulfuron under warm and dry field conditions caused a stunting effect on maize plants (Hybrid F₁, Damon) and reduced yield by 53% compared to untreated control plants; while 5·0 and 10·0 g a.i. ha^-1 of incorporated chlorsulfuron killed all maize plants. However, under wetter field conditions, incorporated chlorsulfuron at 1·25, 2·5 and 5·0 g a.i. ha^-1 caused a stunting effect on maize plants (Hybrid F₁, ARIS) and decreased yield by 16, 57 and 92%, respectively, compared to untreated control. Incorporation of 50 kg ha^-1 of activated charcoal inactivated completely chlorsulfuron incorporated at 1·25 and 2·5 g a.i. ha^-1 and did not affect yield of maize compared to untreated control. Higher rates of activated charcoal such as 100 and 200 kg ha^-1 also inactivated chlorsulfuron applied at 1·25–5·0 g a.i. ha^-1 and did not affect grain yield of maize. Phytotoxicité et persistance du chlorsulfuron Deux méthodes d'essais biologiques, à savoir en boîte de Petri ou en pot, Basées sur la croissance des racines de maïs prégermé ont été utilisées pour étudier la phytotoxicité résiduelle du chlorsulfuron en conditions de plein champ. Les deux méthodes sont également reproductibles et sensibles à des niveaux de détection pour les résidus de chlorsulfuron de 0,25 à 10 ng g^-1. Les résultats montrent que la persistance et la phytotoxicité augmentent avec des doses croissantes de chlorsulfuron, mais la persistance est plus courte dans des conditions de plein champ humides que séches. Une dose aussi faible que 1 g de matiére active ha^-1 de chtorsulfuron incorporé en conditions chaudes et séches a causé un effet retard sur les plants de maïs (hybride F₁, Damon) et a réduit de 53% le rendement par rapport au témoin non traité; des doses de 5 à 10 g de matiére active ha^-1 de chlorsulfuron incorporé ont tué tous les pieds de maïs. Cependant, en conditions plus humides, le chlorsulfuron incorporéà 1,25, 2,5 et 5 g de matiére active ha^-1 a causé un effet retard sur le maïs (hybride F₁ ARIS) et a réduit le rendement par rapport au témoin non traité respectivement de 16, 57 et 92%. L'incorporation de 50 kg ha^-1 de charbon actif a complément inactive le chlorsulfuron incorporéà 1,25 et 2,5 g de matiére active ha^-1 et n'a pas eu de répercussion sur le rendement par rapport au témoin non traité. Des doses plus élevées de charbon actif comme 100 et 200 kg ha^-1 ont inactivé le chlorsulfuron appliquéà 1,25–5 g matiére active ha^-1et n'ont pas affecté le poids en grain du maïs. Ueber die Beeinflussung von Phytotoxizität und Wirkungsdauer von Chlorsulfuron durch Aklivkohle Zum Studium der Residualwirkung von Chlorsulfuron unter Feldbedingungen wurden zwei Bioassaymethoden, eine in Petrischalen, die andere in Töpfen, eingesetzt. Beide Methoden basierten auf dem Wurzelwachstum von vorgekeimtem Mais. Es zeigte sich, dass beide Versuchsverfahren in gleichem Masse reproduzierbar und empfindlich und in der Lage sind Rückstände von 0,25–10,0 ng g^-1 nachzuweisen. Mit steigender Chlorsulfurondosis wurde eine zunehmende Phytotoxizität, Persistenz und Mobilität des Herbizids festgestellt. Die Persistenz war unter feuchten Feldbedingungen kürzer als bei Trockenheit. Bis zu einer unteren Grenze von 1,0 g a.i. ha^-1 verursachte inkorporiertes Chlorsulfuron, unter trockenen und warmen Feldbedingungen an Mais (Hybride F₁, Damon) Wachstumshemmungen und Erntereduktionen von 53%, verglichen mit unbehandelten Kontrollpflanzen. Unter feuchteren Bedingungen, jedoch, hatten 1,25, 2,5 and 5,0 g a.i. ha^-1 eingearbeitetes Chlorsulfuron an Mais (Hybride F₁ ARIS) Wachstumshemmungen und Ernteverluste von 16, 57 und 92% zur Folge. Die Einarbeitung von 50 kg ha^-1 Aktivkohle inaktivierte 1,25 g und 2,5 g ha^-1 inkorporierles Chlorsulfuron vollständig und hatte keinerlei negative Auswirkungen auf die Maisernte, im Vergleich zu unbehandelten Kontrollen. Höhere Mengen von Aktivkohle, wie 100 und 200 kg ha^-1, inaktivierten auch Chlorsulfuronmengen von 1,25–5 g ha^-1 und hatten keinen Einfluss auf den Kömerertrag.     

Fate of chlorsulfuron in the environment. 1. Laboratory evaluations

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 (K_oc 13–54). Soil thin-layer chromatography of chlorsulfuron (R_f=0·55–0·86) and its major degradation products demonstrated that the chlorobenzenesulfonamide (R_f=0·34–0·68) had slightly less mobility and that the triazine amine (R_f=0·035–0·40) was much less mobile than chlorsulfuron. In an aged column leaching study, subsamples of a Fallsington sandy loam (pH_water 5·6, OM 1·4%) or a Flanagan silt loam (pH_water 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     

Weeds resistant to chlorsulfuron and atrazine from the north-east grain region of Australia

The resistance of weeds to triazine and sulfonylurea herbicides has been recorded in several countries. The extent of the problem in the north-east grain region of Australia is uncertain. In an initial study, resistance to chlorsulfuron and atrazine in 15 weed species was investigated. The study showed that at least six of them have evolved resistance to one or other of these herbicides. Two collections of Rapistvum rugosum L., three of Sisymbrium orientale L., five of Sonchus oleraceus L., one of Fallopia convolvulus (L.) A. Love and one of Sisymbrium rhellungii O. Schultz were resistant to the recommended rate of chlorsulfuron (15 g a.i. ha^-1). Resistance to chlorsulfuron was not discovered in three collections of Sisymbrium L., two of Brassica tournefortii Gouan. three of Emex australis Steinh. and 11 of Phalaris paradoxa L. Two collections of Urochtoa panicoides Beauv. were resistant, and three collections possibly resistant, to the recommended rate of atrazine(1.8 kg a.i. ha^-1). Resistance to atrazine was not found in 12 collections of Hibiscus urionum L., nine of Salvia reflexa L., two of Parthenium hysterophorus L., two of Amaranthus viridis L. and 14 of Echinochloa colona (L) Link. The resistance status of four weeds ( R. rugosum. F. convolvulus, S. thellungii and U. panicoides was confirmed using a multiple dose-response screen and is the first report of resistance for these species. Herbicide usage records show that resistance has developed after 3-10 years of selection with chlorsulfuron and 2-15 years of selection with atrazine, with no correlation between the frequency of use and the degree of resistance for any of the species where eight or more collections were made.     

乙草胺碳酸钙微球的制备方法及其缓释性能研究

为增加乙草胺的持效性,将乙草胺与氯化钙-十二烷基硫酸钠溶液混合后与碳酸钠反应制得乙草胺碳酸钙微球。通过扫描电镜、粒径分布仪及高效液相色谱等对该微球进行了表征,并对制备工艺、载药率及缓释性能等进行了探讨。结果表明:碳酸钙载体晶型主要为方解石结构;常温条件下,当n(CaCl2):n (Na2CO3):n(SDS)=1:2:2、搅拌速率为500 r/min、搅拌时间为10 min时,损耗率为0.2%,载药率接近20%;所得碳酸钙微球呈球形,粒径分布窄,且呈正态分布;微球中乙草胺的释放速率随温度和pH值的升高而增加。该微球制备工艺的优化及缓释性能研究结果可为田间定时、定量的释药研究及应用提供参考。     

Mobility and leaching of glyphosate: a review

There is currently concern that glyphosate, a strongly sorbing non-selective herbicide which is widely used in Europe, may be leached from the root zone into drainage water and groundwater. The purpose of this review is to present and discuss the state of knowledge with respect to the mobility and leaching of glyphosate from agricultural soils. Specific attention is given to the adsorption behaviour of glyphosate and the analysis of available studies on glyphosate transport. In addition, there are a number of experimental and numerical studies indicating that other strongly sorbing substances may be transported rapidly to the sub-surface. The experimental studies analysed in the paper encompass column-, lysimeter- and field-scale experiments on glyphosate transport. The experimental findings, combined with transport studies on other strongly sorbing pesticides in the literature, support the hypothesis that transport of glyphosate may be caused by an interaction of high rainfall events shortly after application on wet soils showing the presence of preferential flow paths. Concentrations of glyphosate in European groundwater have been reported occasionally but monitoring is still limited.     

Resistance of Raphanus raphanistrum to chlorsulfuron in the Republic of South Africa

Herbicide resistance poses a substantial threat to the agricultural industry throughout the world and during the past decade several reports regarding herbicide resistance have been published. Raphanus raphanistrum L., from two wheat farms located in the winter rainfall region of South Africa, showed indications of resistance to chlorsulfuron. Seeds from these suspected resistant biotypes as well as seeds from a susceptible biotype were collected and transported to the ARC-Small Grain Institute for herbicide resistance studies. Herbicides registered for R. raphanistrum control, i.e. chlorsulfuron, MCPA and bromoxynil, were used in this study. Significant differences in the degree of control were found between the susceptible and two resistant biotypes, when treated with chlorsulfuron. The LD₅₀ values for the resistant biotypes (WR 1 & WR 2) were 45 and 11.3 g a.i. ha^–1, respectively, whereas the LD₅₀ value for the susceptible biotype was 5.6 g a.i. ha^–1. The almost eightfold difference between the susceptible and resistant biotype (WR 1), indicated that resistance has developed to chlorsulfuron. Only twofold resistance was established between the other resistant biotype (WR 2) and the susceptible biotype. Significant differences between herbicide rates were also established with the MCPA and bromoxynil experiments. No significant difference could, however, be found between the susceptible and resistant biotypes when treated with MCPA and bromoxynil, indicating the importance of different modes of action of herbicide as a strategy to prevent herbicide resistance.