Einfluss von Pflanzenschutzmitteln einer Zuckerrüben-Spritzfolge auf biologische Aktivitäben und auf den Abbau von Chloridazon im Boden. I. Freilandversuche

Effects of rarious pesticides of a sugar-beet spray programme on boilogical activities and chloriduzon degradation in soil. I. Feied experiments In a long-term field experiment at three different sites with similar soil and climatic conditions. The effect on chloridzon (Pyramin)-applied alone and in combination with other persticides of a sugar-beet spray programme-on b iological soil activites (dehydrogenase, straw decomposition) and aslo on degradation and plant availability of chloridazon in the soil were investigated. After an initial lag-period, chloridazon was degraded rapidly and 50% of the initial concentration disappeared in 18–53 days, in different years. The amount of chloridazon available to plants expressed as percent of the total amount of herbicide in the soil was 30% at the day of application and about 2% on day 36. Chloridazon persistence in the soil was unaffected by the other pesticides of the spray programme. Dehydrogenase activity was not significantly inhibited by Pyramin alone. However, with the spray programme an inhibitory effect was noticed, especially om the 0–5 cm soil layer in some plots, which lasted until harvest. There was no correlation between biological soil activities and the total and water-extractable chloridazon residues respectively.     

Untersuchungen zum Einfluss einer Pflanzenschutzmittelspritzfolge auf das Rückstandsverhalten von Terbutryn und die mikrobielle Aktivität im Boden. Teil II. Beeinflussung der mikrobiellen Aktivität

Studies on the effect of a pesticide spray sequence on the behaviour of terbutryn residues and on soil microbial activity. Part II. Influence on microbial activity In laboratory incubation experiments (at 10 and 20°C and 30 and 60% soil water-holding capacity) soil microbial activities (dehydrogenase, respiration after glucose amendment and nitrogen transformations) were scarcely affected by 20·9 and 28·0 mg kg^?1, respectively, of terbutryn in two soils of different sorption properties. In contrast, dinosebacetate, alone or mixed with terbulryn, triadimefon or parathion, inhibited dehydrogenase activity and respiration even at a low rate of application (2·87 mg kg^?1). Following application of a 10 times higher rate to a highly adsorbent soil there was an initial inhibition of nitrification followed by an enhanced rate of nitrogen mineralization. Triadimefon and parathion, alone and in combination with other pesticides, caused both stimulation and inhibition of microbial activity; the reason is not clear. The effects on dehydrogenase and respiration were confirmed in field experiments. Dehydrogenase activity was the most sensitive and so could be a useful test for the side-effects of pesticides on soil micro-organisms. Additional work on nitrogen transformations is needed to interpret the results.     

Untersuchungen Zum Einfluss einer Pflanzenscutzmittelspritzfolge auf das Rückstandsverhalten von Terbutryn und die mikrobielle Aktivität im Boden. Teil I. Rückstandsverhalten von Terbutryn

Studies on the effect of a pesticides spray sequence on the behaviour of terbutryn residues and on soil microbial activity. Part I. Behaviour of terbutryn residues In laboratory incubation studies (at 10 and 20°C and 30 and 60% soil water-holding capacity) terbutryn dissipated with half lives of 19–113 days at a standard rate of application (2·09 or 2·8mg kg^?1) and 62–258 days at a 10-fold higher rate. There was little difference between two soils of different sorptive properties. The water-extractable residues showed that terbutryn was extensively adsorbed by both soils with only 12–18%‘plant-available'. Persistence of terbutryn in the field was consistent with the laboratory results and was predicted satisfactorily with a mathematical simulation model. In the laboratory, terbutryn breakdown was inhibited by the simultaneous application of dinoseb acetate and stimulated by triadimefon and parathion but these results were not confirmed in the field.     

Anwendung von Isoproturon, allein und in Kombination mitanderen Wirkstoffen, im Nachauflauf–Winter (NA–W) und Nachauflauf–Frühjahr (NA–F) zu Winterweizen und Wintergerste

Use of isoproturon, alone and in combination with other compounds, post–emergence in winter and spring, on winter wheat and winter barley. II. Side effects on dehydrogenase activity, nitrogen transformation and straw decomposition in the soil The effect of isoproturon, alone and combined with dinoseb acetate and bifenox, on dehydrogenase activity, nitrogen transformations and straw decomposition following post–emergence application in winter and spring to winter wheat and winter barley was studied over two years at two sites. Isoproturon caused limited transient stimulation and inhibition of dehydrogenase activity, maximum 40%, and nitrogen turnover, 70–90%. Dinoseb acetate reduced general metabolic activity by up to 30%. Ammonium and nitrite concentrations were at times more than 100% higher than control values. In the laboratory, with temperature, soil moisture and sampling times similar25 to those in the field, isoproturon caused reductions in dehydrogenase activity in only a few cases but dinoseb acetate reduced the activity by up to 50%. The herbicide effects were clearer in a sandy than in a clay soil. The effect of time of application on the response of soil microbial activity to herbicides was evident only in the field.     

Efficiency of a bagasse substrate in a biological bed system for the degradation of glyphosate, malathion and lambda-cyhalothrin under tropical climate conditions

BACKGROUND: After the rinsing of spray equipment, the rinsing water contains polluting products. One way to avoid pollution is to bring the rinsing water over a purification system, a biological bed. The system consists of an impermeable tub filled with a biomix substrate that facilitates biodegradation of pesticides. Usually, straw is one component of the biomix. The objective of this study was to assess the efficiency of an unusual substrate, bagasse, a residue of sugar cane, for the degradation of three pesticides, glyphosate, malathion and lambda‐cyhalothrin. RESULTS: Results showed that more than 99% of malathion and glyphosate were degraded in 6 months. In the biological bed, the DT₅₀ value for malathion was 17 days, for glyphosate 33 days and for lambda‐cyhalothrin 43 days. The degradation rate of aminomethylphosphonic acid (AMPA) residues from the degradation of glyphosate was slower than that of the other pesticides (DT₅₀ 69 days). Finally, the innocuousness of the biomix after 6 months of degradation was confirmed by biological tests. CONCLUSIONS: Although the degradation rates of the three pesticides in the present bagasse‐based system were similar to those under temperate conditions, the degradation conditions were improved by comparison with those in soil under the given tropical conditions. Further benefits of this system are pesticide confinement, to avoid their dispersion in the environment by liquids or solids, and a lower overall cost. Finally, possibilities for optimising the bagasse‐based system (e.g. management of the water content and nature of the biomix) are discussed. Copyright © 2008 Society of Chemical Industry     

Einfluss von herbizidem Citronella-Öl und Neem (Azadirachtin) auf mikrobielle Aktivitäten im Boden

Within plant protection the products from citronella oil and neem mostly were used against pests. Their application for weed control is still at the beginning. This special application, however, needs higher dosages. The possible soil contamination and the missing microbiological-ecotoxicological information initiated our laboratory trial. The dosages used were relatively high as was necessary for weed control. They allowed the investigation of dose-effect relationships. In a loamy sand soil the biomass-related dehydrogenase activities as well as the carbon mineralization (actual and cumulative CO₂ formation) were measured. Because a soil with and without lucerne meal amendment was used the specific activity increase (=?LIA) could be calculated for both microbial parameters. Mostly both microbial activities were dose-dependently stimulated by the neem compound. Citronella oil at the beginning inhibited with the higher dosages and later on stimulated these activities. Most of the stimulations may be caused by the microbial decomposition of the organic compounds amended to the soil, which overlie some expected biocidal effects. This allows a preliminary estimation of the microbiological-ecotoxicological effects as less critical. Depending on the very high amounts needed for weed control, however, a final evaluation should consider additional investigations with further microbial activities and other soil organisms.     

Effects of herbicide-fertiliser interactions on nitrogen and phosphorus transformations and herbicide persistence in soil

The effects of seven herbicides, alone or combined with a commercial compound fertiliser, on nitrogen and phosphorus transformations in soil, were investigated in the laboratory. No significant effect was observed without the fertiliser. When the fertiliser (N:P:K ratio 20:14:14) was applied (2 gkg^?1 of soil), asulam markedly reduced nitrification, while increasing the mineralisation of nitrogen; chloridazon, glyphosate, isoproturon and paraquat all prevented the reduction in available phosphate that occurred in the control soil in the first 2 weeks. The rates of degradation of dalapon and isoproturon were greatly reduced in fertilised soil. The importance of these results is discussed in the context of the requirements of registration authorities.     

玉米秸秆对4种农田杂草生长的抑制作用

通过室内试验研究了玉米秸秆不同部位对鳢肠、反枝苋、马唐、稗等农田杂草幼苗生长的影响,并通过盆栽试验研究了玉米茎粉末对供试杂草的防治潜力。结果表明,玉米秸秆根、茎、叶均可显著抑制供试杂草胚根(种子根)的生长,但对供试杂草胚轴(胚芽鞘)生长的作用不一。在不同的部位中,以玉米茎的活性更高。盆栽试验结果表明,玉米茎粉末对供试杂草有较好的防治效果,用量为10g/kg时对4种供试杂草的株高抑制率和鲜重防效均高于80%。     

Characterization of Spatial Variability Structure in Three Separate Field Trials on Pesticide Dissipation

Experiments were carried out on three Italian farms to assess the degree of spatial variation of pesticide field concentration during treatment and during dissipation trials. Test pesticides were chloridazon and metamitron (both sugar-beet herbicides) applied as a tank mix. The classical statistical technique and geostatistics were used to summarize and evaluate variable spatial data. The results show that the actual values of pesticide concentration for application rate and initial concentration in all three areas are lower than expected, thus indicating that under field conditions only a part of the pesticide reaches the soil during the distribution. The actual values for both herbicides in all three areas expressed as percentage of expected values ranged from 44·1% to 64·2% for application rate and from 40·5% to 99·5% for initial concentration. The coefficient of variation was similar for both pesticides and ranged from 23·8 to 74·1 for application rate, 24·1 and 58·8 for initial concentration and 11·1 and 110·0 for dissipation half-lives. The high variability in application rate and initial concentration could be ascribed to an uneven herbicide distribution, and in dissipation studies to variation in half-lives for the rate of herbicide loss from soil in different parts of the field. Geostatistic analysis indicated little spatial correlation, probably because the sampling sites were widely spaced on the field. In all cases, the data were not sufficient to estimate the range of influence, probably because of the size of the experimental fields and the sampling strategy. © 1997 SCI.     

Wirkung von Neem-Produkten auf höhere Pflanzen und ihre mögliche Nutzung zur Reduzierung der Seitentriebe von Kulturpflanzen sowie zur Unkrautbekämpfung – eine Bestandsaufnahme

The neem tree (Azadirachta indica A. Juss) offers many possibilities of usage. In plant protection mostly the insecticidal activity of neem products is important. In different parts of the plant several biologically active substances occur. One is the active ingredient azadirachtin, which already is commercially used as an insecticide against insect pests. Some active ingredients of neem may be systemically taken up by the treated plants. Often a rapid decomposition occurred which was enhanced by UV radiation. Therefore formulated neem products often need a UV blocker to elongate their activity. After the application of neem products within plant protection sometimes phytotoxic effects could be observed on different plant species. This phytotoxicity can be used to reduce suckers on tobacco plants and recently also on eucalyptus plants. The existing trials to use neem products for weed control mostly concentrated on the direct treatment of some parasitic weeds like Cuscuta, Orobanche and Striga as well as on a few other weeds (e.g. Echinochloa crus-galli). Mostly the growth of the weeds which were often repeatedly treated with high dosages was reduced, but many plants remained still alive. At present the potential of neem products for an effective weed control is not sufficiently investigated. As a consequence of some already known insecticidal and microbiocidal activities of many neem products also side effects on parts of the epigeic and soil fauna and on the nitrification should be considered after usage for weed control.     

Effect of abamectin on root-knot nematodes and tomato yield

BACKGROUND: Tomato growers in Shandong Province, China, commonly face heavy root‐knot nematode infestations. Current methods of control include cadusafos and methyl bromide (MeBr), but alternative methods are required because of the high toxicity of these pesticides and the ecological risk of their use. Therefore, abamectin soil applications were evaluated for their potential to control soil nematodes in a series of laboratory tests, greenhouse pot experiments and field trials. RESULTS: Laboratory tests showed that abamectin exhibited rapid knockdown of Meloidogyne incognita, with LC₅₀ and LC₉₀ values that were superior to those of cadusafos and averaged 7.06 and 21.81 mg L^?1. In the greenhouse pot experiment, soil applications of abamectin provided significant M. incognita control similar to that provided by cadusafos while maintaining excellent plant height and vigour. In the field trials, abamectin exhibited excellent control effects to nematodes while giving a higher tomato yield. There was a 19.3–39.0% yield increase from the various treatments compared with the control, and the best results were obtained from the highest dose of abamectin. CONCLUSION: The results of this study demonstrated that abamectin has the potential to be used as an effective alternative to MeBr and cadusafos for nematode control in tomato production in Shandong Province. Copyright © 2012 Society of Chemical Industry     

Influence of straw management, nitrogen fertilization and dosage rates on the dissipation of five sulfonylureas in soil

The dissipation behaviour of metsulfuron-methyl, tribenuron-methyl, thifensulfuron-methyl, triasulfuron and amidosulfuron were studied in soil following post-emergence spring applications to cereal crops. Incorporation or removal of straw and different fertilizer applications had no influence on the disappearance time (DT₅₀) of the herbicides. However, in laboratory trials dissipation of metsulfuron-methyl, triasulfuron and amidosulfuron at higher application rates was accelerated after incorporation of straw into the soil. The addition of straw decreases soil pH thereby causing faster hydrolysis of the compounds. Addition of nitrogen fertilizer increased the half-lives (t_1/2) of the herbicides. Combination of both straw and N fertilizer, however, had no effect. Neither straw nor N influenced the degradation of tribenuron-methyl and thifensulfuron-methyl.
The DT₅₀ of all herbicides investigated varied from 6 to 17 days in the field trials. Except for amidosulfuron, herbicides could not be detected 38–68 days after application. In the laboratory, t_1/2 values were higher than those in the field at 75 days (amidosulfuron), 63 days (metsulfuron-methyl), 35 days (triasulfuron) and 13 days (tribenuron-methyl). Only the t_1/2 of thifensulfuron-methyl was at 29 h faster under laboratory conditions. T_1/2 values of all herbicides were influenced by their initial concentration. The t_1/2 values of amidosulfuron and tribenuron-methyl at 1 mg a.i. kg⁻¹ soil were 2–2.5 times higher than at the recommended field application rate of 42 μg a.i. kg⁻¹ soil.     

多功能菌B1514在小麦根际的定殖及对纹枯病的防治作用

为明确多功能菌B1514对小麦纹枯病的防治效果,采用紫外诱变和逐步提高诱导浓度法筛选获得抗性菌株,分析其在小麦根际和根内的定殖动态,通过盆栽和微区试验测定其对纹枯病的防治作用。结果表明,用发酵液浸种后B1514在小麦根际和根内定殖时间分别达49 d和28 d以上;添加玉米秸秆可延长其在根际和根内的定殖时间。B1514发酵液浸种对小麦纹枯病的盆栽防效低于对照药剂60 g/L戊唑醇悬浮种衣剂;土壤中添加秸秆能提高发酵液浸种处理的防效,可达85.3%,且与戊唑醇无显著差异。田间试验结果显示B1514浸种同时添加发酵物处理的持效期较长,在小麦成熟期防效优于戊唑醇,为55.2%;秸秆降解率也高于对照,为45.5%。表明B1514有加速玉米秸秆降解和防治小麦纹枯病的作用。     

含肟醚并取代异 NFDA1唑环的氨基甲酸酯类化合物的合成及生物活性

为寻找具有优异生物活性的氨基甲酸酯类化合物,根据活性亚结构拼接原理,将取代异 NFDA1 唑和肟醚基团引入多菌灵结构中,以取代苯甲醛 (1) 和2-氯苄胺(3) 为起始原料,经多步反应设计合成了10个未见文献报道的含肟醚并取代异 NFDA1 唑的氨基甲酸酯类化合物,其结构经 1H NMR 和 MS 确证。初步生物活性测定结果表明,部分目标化合物不仅具有一定的杀菌活性,同时还具有较好的除草活性。其中,活体盆栽试验结果表明,化合物11b对黄瓜霜霉病Pseudoperonospora cubensis 的相对防效为90%,对黄瓜白粉病Sphaerotheca fuliginea 的相对防效达95%,低于对照药剂多菌灵;除草活性皿测法表明,化合物11c和11j 200 mg/L下对靶标作物的根、茎抑制率均达80%以上,与对照药剂异丙酯草醚活性相当。盆栽法表明,150 g/hm2下,化合物11c和11j对繁缕Stellaria media苗前和苗后的抑制率均在70%以上,低于异丙酯草醚。此类化合物的构效关系有待进一步研究。     

生物土壤添加剂对连作黄瓜防御酶系及酚类物质含量的影响

 The changes of several defense enzyme activities and phenolic compound in cucumber roots were examined after biological soil amendment(BSA) was applied to the cucumber continuous cropping through pot trials.It could promote seedling growth and reduce disease incidence.The results showed that the activities of defense enzymes such as peroxidase(POD),polyphenol oxidase(PPO) and TTC in treated cucumber roots were measured significantly higher than that of control.The activities of POD and PPO in BSA-treated roots were significantly higher than that of control after inoculation with Fusarium oxysporum(Schl.)f.sp.Cucumerinum.Phenolic compound content of roots decreased in the initial period of inoculation,increased after di-sease incidence,but it was higher in BSA-treated than that of control.These indicated that BSA could induce the defense enzyme activities and increased phenolic compound in cucumber roots.     

Degradation of isoproturon and bentazone in peat- and compost-based biomixtures

BACKGROUND: The composition and properties of a biomixture used in a biobed are decisive for pesticide sorption and degradation. This study was performed to investigate the capability of compost‐based substrates in mixtures with citrus peel and vine branch straw and peat‐based substrates in mixtures with soil and vine branch straw at different levels in order to degrade isoproturon and bentazone. RESULTS: Dissipation and mineralisation rates of both pesticides were determined, and metabolic activity was followed as respiration. Compost‐based substrates showed faster pesticide dissipation in the presence of lignocellulosic materials, as in garden compost and vine branch straw. The increasing content of vine branch straw in peat‐based substrates does not seem to affect dissipation of the parent compounds. Low mineralisation rate was observed in all treatments. CONCLUSION: Higher pesticide degradation was observed in the lignocellulosic substrates, probably because of the development of lignin‐degrading microorganisms which have shown to be robust and are able to degrade recalcitrant pesticides. Copyright © 2010 Society of Chemical Industry     

Effects of straw and silicon soil amendments on some foliar and stem-base diseases in pot-grown winter wheat

Four foliar and two stem-base pathogens were inoculated onto wheat plants grown in different substrates in pot experiments. Soils from four different UK locations were each treated in three ways: (i) straw incorporated in the field at 10 t ha⁻¹ several months previously; (ii) silicon fertilization at 100 mg L⁻¹ during the experiment; and (iii) no amendments. A sand and vermiculite mix was used with and without silicon amendment. The silicon treatment increased plant silica concentrations in all experiments, but incorporating straw was not associated with raised plant silica concentrations. Blumeria graminis and Puccinia recondita were inoculated by shaking infected plants over the test plants, followed by suitable humid periods. The silicon treatment reduced powdery mildew ( B. graminis ) substantially in sand and vermiculite and in two of the soils, but there were no effects on the slight infection by brown rust ( P. recondita ). Phaeosphaeria nodorum and Mycosphaerella graminicola were inoculated as conidial suspensions. Leaf spot caused by P. nodorum was reduced in silicon-amended sand and vermiculite; soil was not tested. Symptoms of septoria leaf blotch caused by M. graminicola were reduced by silicon amendment in a severely infected sand and vermiculite experiment but not in soil or a slightly infected sand and vermiculite experiment. Oculimacula yallundae (eyespot) and Fusarium culmorum (brown foot rot) were inoculated as agar plugs on the stem base. Severity of O. yallundae was reduced by silicon amendment of two of the soils but not sand and vermiculite; brown foot rot symptoms caused by F. culmorum were unaffected by silicon amendment. The straw treatment reduced severity of powdery mildew but did not detectably affect the other pathogens. Both straw and silicon treatments appeared to increase plant resistance to all diseases only under high disease pressure.     

Prognose-Modell zur Erfassung des Rückstandsverhaltens von Metribuzin und Methabenzthiazuron im Boden und deren Auswirkungen auf Folgekulturen

A predictive model for the assessment of metribuzin and methabenzthiazuron residues in soil and their effects on succeeding crops Aus der simulierten Abbaukurve lassen sich somit für jeden beliebigen Zeitraum nach Applikation eines Herbizids die maximalen pflanzenverfügbaren Wirkstoffanteile ableiten, aus denen die Auswirkungen auf mögliche Folgekulturen prognostiziert wurden. Die relative Empfindlichkeit (im Bereich der ED₅₀) der untersuchten Kulturpflanzen in Hydroponik war bei Metribuzin: Möhre < Bohne = Salat < Erbse = Spinat und bei MBT: Bohne = Erbse = Salat < Spinat = Möhre. Weiterhin konnte gezeigt werden, dass unter Labor- und Freilandbedingungen evtl. auftretende Schäden in fast allen Fällen in den gleichen Aktivitäskategorien lagen. The degradation of the herbicides metribuzin and methabenzthiazuron (MBT) was simulated under outdoor conditions in a sandy soil by a computer model based on the dominating influence of temperature and moisture on degradation, which is measured in preceding laboratory experiments. Depending on the conditions of incubation (10–30°C, 20–90% water holding capacity) the half-life of metribuzin was 11–60 days and of MBT 42 > 1200 days. Knowing the plant available soil water, the fraction of a total herbicide residue potentially available to plants can be calculated from the distribution coefficient (K_d-value). In the soil under investigation, for metribuzin 77% and for MBT 16% of the total residue was available to plants. Thus, the maximum residue available to plants can be calculated from the simulated degradation curve for any period after the application of a herbicide and in combination with a predictive model the effect on succeeding crops can be predicted. The specific susceptibility of the crops in question has to be established in preceding hydroponic culture experiments. The relative susceptibility (about ED₅₀) of the plants in hydroponic-culture was earrot相似文献   

Isolation of antagonistic <Emphasis Type="Italic">Streptomyces</Emphasis> sp. against a potato scab pathogen from a field cultivated with wild oat

Fungi, actinomycetes, and bacteria isolated from soil and plant samples from a potato field in which wild oat (Avena strigosa) had been pre-cultivated were screened for microorganisms that can be used as biocontrol agents for common scab of potato. Of 342 isolates assessed in initial pot trials for their suppressive effect on the severity of potato scab caused by Streptomyces turgidiscabies, 26 isolates were selected as antagonistic candidates based on their ability to reduce disease severity, then tested in a second pot trial. Of the 26, five actinomycetes, isolated from either the rhizosphere soil of wild oat or the soil adhering to potato stolons and tubers, were selected as antagonists. A comparison of partial sequences of 16S rRNA genes from the five isolates indicated that they belong to the genus Streptomyces. Of these five, WoRs-501 most strongly inhibited in vitro mycelial growth of S. turgidiscabies and was also the most effective in suppressing potato scab in a third field pot trial. In that pot trial, a 10% (v/v) mix of WoRs-501 (6.2 × 10⁸ colony-forming units [CFU]/g dry mass) decreased the disease severity by 78–94% in comparison with the untreated control at 5 × 10⁴ to 5 × 10⁶ CFU S. turgidiscabies/g dry soil. WoRs-501 also grew well in vitro at a wide range of pH levels and temperatures. These results suggest that WoRs-501 is a promising candidate for biocontrol of potato scab.     

Plant-derived natural products exhibiting activity against formosan subterranean termites (Coptotermes formosanus)

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is among the most devastating termite pests. Natural products derived from plant extracts were tested in a discovery programme for effective, environmentally friendly termite control agents. Among the natural products tested, vulgarone B (isolated from Artemisia douglasiana Besser), apiol (isolated from Ligusticum hultenii (Fern.) Calder & Taylor) and cnicin (isolated from Centaurea maculosa Lam.) exhibited significantly higher mortalities than in untreated controls in laboratory bioassay. These compounds are present at high levels in their respective plant sources and also possess other biological activities such as phytotoxic and antifungal properties.