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   

Einfluß von Diclofop-methyl auf Wachstum und Entwicklung der Keimlinge von Zea mays L.*

Effect of diclofop-methyl on the growth und development of Zea mays L. seedlings Diclofop-mcthyl, a diphenoxypropionic acid herbicide, had no effect on the germination of maize (Zea mays) seed. Prc-ger-minated maize embryos showed inhibited radicle growth when treated with the herbicide, but those of beans were considerably less sensitive. The inhibitory effect of the herbicide on maize radicle growth was reversed when the embryos were transferred to herbicide-free medium within 24 h of treatment. The higher concentrations of diclofop-methyl tested (≥10^?6 M) induced necrosis on the second day of treatment, which first appeared in the meristematic and elongation zone of the root tip and then via the rest of the root to the grain. The herbicide increased the fresh and dry weight as well as the dry matter content of the radicle tips of Zea mays. These effects were attributed in an accumulation of cell wall material in the herbicide-treated root lips. In the presence of hydroxyurea, a selective inhibitor of cell division, the effect of diclofop-melhyl on radicle elongation was reduced but did not cease complelely. From these results it can be concluded that diclofop-methyl interferes with the processes that effect both cell division and cell elongation.     

Der Einfluss der Reifedifferenz von Korn zu Restpflanze auf den optimalen Erntezeitpunkt und die standortgerechte Sortenwahl von Energie- und Silomais

Maize production trials carried out in eastern middle of Germany from 1999–2008 were used for statistical analysis of the optimum date for silage maize ripeness. The Knowledge about difference in ripeness between grain and residual plants at the harvest were used for exactly choice of cultivar under drought conditions for silage and energy maize. The Silage maize Ripeness Index (the ratio of dry matter content of maize grains to dry matter content of residual plants) is more suitable for the leading of plant development, the determination of harvest date and the choice of cultivar as the dry matter content of the plant. The analysis is cheaper as well as not so material and time-consuming with a better financially results in food-, milk- and methane production in comparison to the dry matter content of the silage maize of different hybrid maize populations and environments. Ensilage optimum and yield maximum correspond with the physiological ripeness of silage maize and are close to the grain dry matter content of 64%, to the dry matter content of starch of 33% and a ripeness index from 2.55 to 2.9 for parameter of quality and quantity. Only under these conditions it is possible to reach the optimal ripeness of 33 to 35% in the whole plant silage maize. But under suboptimal conditions the harvest is carried out, if SRI had a maximal value. In dependence on the Silage maize Ripeness Index (SRZ) and (SRI) parameters of silage and energy maize were predicted differential development of ripeness and yield. The aims of silage and energy maize are similar. The Silage maize Ripeness Index (SRI) is, for whole plant maize, better than the Whole Plant Maize Ripeness Index (SRZ) for the choice of a hybrid in Germany. The dry matter content of grain in interaction with the dry matter of residual plants are better than dry matter content of the whole plant maize as ripeness indicator in the production of silage and energy maize at the harvesting time. SRI is also universal suitable for use as a standard in scientific trials and for better characteristic of cultivar types and environmental influence.     

Untersuchungen zur Fangleistung von Schlitzfallen und Fangholzhaufen bei der lokalen Dichteabsenkung von Buchdrucker (Ips typographus)-Populationen

Two kinds of pheromone-based trap systems are used in the integrated system against the European Spruce Bark Beetle: a standardized commercial slot-trap and an attract-and-kill system using insecticide-coated spruce wood. To determine the individual benefits and limits in both systems, a comparative survey has been done in 2008, respecting the slightly different requirements for deploying both systems with maximum efficiency. The observed results showed that both systems are able to attract large numbers of spruce bark beetles, however the wooden attract-and-kill system removed both larger numbers and higher percentages of the attracted individual beetles. During the survey, the wood traps were able to incapacitate between 80 and 90?% of the attracted beetles, while the slot-traps kept only 50?C60?% contained. While the use of a non-specific insecticide in a freely accessible trap system always bears the risk of attracting and killing individuals of non-targeted species, the survey gave no indication that specialised antagonists of the spruce bark beetle or other non-target-species has been overly affected. The percentage of non-target-organisms has been 0.3?% in total. It was concluded that, while both systems have the capability to reduce the local population of European Spruce Bark Beetles, the natural wood trap system using an insecticide has the ability to control a much larger population and should therefore be considered the primary choice if the conditions on the site indicating a high risk of a continuous bark beetle infestation.     

Einfluß des Applikationsortes auf die Penetration und Translokation von Diclofop-methyl bei Flughafer (Avena fatua L.)

Effect of the type of application on the penetration and translocation of dictofop-methyl in wild oats (Avena fatua L.) An investigation was curried out with wild oats on the effect of different types of application between the apex and the base of the shoot on the penetration and translocation of ¹⁴C-diclofopmethyl Penetration at the base of the leaf blade is 64% higher in the first leaf and 95% higher in the second than at the lip of the respective leaves Basipetal translocation of ¹⁴C-diclofop-methyl is limited so the nearer to the base of the shoot the herbicide application is made, the higher will be the amount of ¹⁴C-diclofop-methyl at the shoot base which is the principle site of activity Application at the base of the leaf blade gave the optimum distribution of ¹⁴C-diclofop-methyl in the plant. One reason for this is that, with this type of application, the herbicide solution runs down into the leaf sheath giving rise mechanically to basipetal penetration within the sheath into the zone of meristematic tissue at the base of the shoot. These findings lead to a demand for the most accurate possible placing of diclofop-methyl in the zone of the base of the shoots.     

Die Wirkung mechanischer und chemischer Freistellungsverfahren auf die Entwicklung von Fichten und Kiefern

The effect of mechanical and chemical release on the growth of spruce and pine Trials were carried out in North Rhine-Westphalia on plots in typical spruce- and pine-growing areas to evaluate the following treatment variants: cutting/ slashing, herbicides before planting and herbicides after planting, maintenance of total weed-free plots. The variants were further divided into spot, strip or overall treatments. The trial was carried out on nine sites which were divided into three parts consisting of: five spruce plots infested with a mixed weed population; two spruce plots infested with bracken; two pine plots, one infested with grass and one with bracken. On the last four mentioned plots the nine treatment variants had to be partially restricted. Assessment at four different times after planting produced the following results.

• 1 On the five plots with spruce and a mixed weed population, there were differences between the treatments in respect of tree less, though these were not significant. Differences in annual growth in terms of tree height became apparent in the third and fourth year, but, viewed as an average of all plots, there was still no significant difference in terms of aggregate height. The effect on tree width was somewhat more pronounced, but a distinct growth increase was only apparent on the plots that were maintained weed free, a procedure which was uneconomic. Slashing, according to intensity, resulted in rather targer growth increases than did the use of herbicides after planting; herbicides applied before planting performed rather better.
• 2 On the two spruce plots infested with bracken there was likewise no difference between the treatments in terms of tree loss. On the other hand, plots slashed late and those maintained weed free showed increases in tree height of 20%. Tree width was promoted by all treatments, least by slashing or herbicides applied strips before planting, and most where plots were weed free.
• 3 On the grass- or bracken-infested plots the pines responded more to any reduction in competition than did the spruces. On the grassy plots tree losses were reduced only by complete removal of the ground cover, while in bracken reduction in loss was also evident by slashing and herbicides applied before planting. The effects on growth in terms of aggregate height were not entirely clear, but there appeared to be some response as measured by the diameter of the shoot bases. On the grassy plots slashing was ineffective whereas the herbicides were beneficial in that they removed competition from the roots of the ground cover plants. On the bracken-infested plots late cutting had the least effect. The efficiency of herbicides applied before planting was impaired by ingress of weeds from the periphery of plots towards the end of the trial.

Thus in the case of spruce, apart from extremely competitive situations, normal weed control treatments do not appear to be likely to promote young growth or to affect tree survival rate, and they cannot be recommended for normal conditions. Pines, on the other hand, arc more responsive. They can on occasions benefit from the use of herbicides to remove grass vegetation which, with slashing, is not possible.     

Das Vorkommen von Mehltaupilz auf der Wiesen-Platterbse (Lathyrus pratensis L.)

The aim of small-site experiments carried out in the area of the foothills of the ?umava Mts. was to determine the etiological agent of the disease of meadow peavine (Lathyrus pratensis L.). The experimental locality (Kaplice-Chuchelec) was situated in an altitude of 655?m a.s.l. The investigation was accomplished in the years 2004–2005. During the vegetation period we observed whitish to grey-white soft cover of mycelium on the leaves of meadow peavine. These characteristic symptoms of powdery mildew (Erysiphe trifolii Grev.) were found on the plants in the observed area at the end of summer and in autumn. In the area of interest with permanent grassland we evaluated the following variants: first M – mulched stands (mulched once), second L – fallow stands, third K – mown stands (mowing once to three times), and fourth P – pasture stands (grazed by cattle twice to four times). The observed stands were managed in different ways from 2000, and in relation to the ways and intensity of management we observed the changes and coverage of creeping legumes including Lathyrus pratensis. Phytopathological analysis of plants with the symptoms of Erysiphe fungi attack was accomplished in all variants and repetitions during the whole vegetation period. The observation of particular variants was carried out in four repetitions, the size of the sites being 30?m² (4?×?30?m²), and we evaluated the total number of Lathyrus pratensis plants as well as the number of the plants attacked by powdery mildew. Powdery mildew occurrence on Lathyrus pratensis at different management methods of grass stands was statistically processed (in STATISTICA program). The three-year investigation of Lathyrus pratensis L. yielded statistical evidence that the most significant growth of fungal disease Erysiphe trifolii Grev. was recorded in fallow stands. On the other hand, the least occurrence of the disease was found in the pasture stands, which were grazed by the cattle.     

Überleben von Ralstonia solanacearum Biovar 2 (Rasse 3), dem Erreger der Schleimkrankheit der Kartoffel, in Boden und auf verschiedenen Materialien (Mikrokosmos)

Microcosm studies were carried out to test the survival of Ralstonia solanacearum biovar 2 (race 3) in soil at the permanent wilting point (wp) water content and at field capacity (fc) water content and on various material. Soils were placed at permanent ?5°C, 4°C, 15°C and 20°C and weekly fluctuating ?10/0/+10°C and the material at 5, 15 °C, 20°C with relative humidity (rh) uncontrolled or at constant 10% or 90%. In soil, survival was clearly dependent on temperature independent of water content. At 20°C Ralstonia solanacearum could be reisolated up to 364 days, at 15°C up to 290 days, at 4°C up to 209 days and at fluctuating temperatures (?10/0/+10°C) only up to 18 days. The lower the temperature, the more the population declined. At 15°C and 20°C appr. 10⁷ cfu/g soil were detected after 100 days, whereas at ?5°C only 10² cfu/g soil were detected after only 18 days. The pathogen was longer detectable in sandy-clay loam than in lighter sandy soil. It could be longer reisolated at wilting point and the populations did not decline as rapidly as at field capacity. Ralstonia solanacearum could best survive on material surfaces like rubber, plastic and varnished metal with maximum survival of 40 days at 5°C and 10% rh. In general there is a low risk of Ralstonia solanacearum overwintering under European climatic conditions when the fields are cleared of plant debris and the soil is frozen. Contamined material surfaces pose the risk of pathogen transmission to healthy tubers.     

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.     

Zu den Ausbreitungswegen von Phytophthora ramorum an Rhododendron und Viburnum auf Container-Stellflächen

In Europe, Phytophthora ramorum basically infects Rhododendron and Viburnum. To prevent the spread of the new quarantine organism in nurseries more knowledge about the transmission biology of this pathogen is necessary. For this reason the pathways of spread for P. ramorum on the two main host plants have been studied for the first time. Under practical field conditions inoculated plants were placed as sources of infections in a larger stock. Over 3?months the development of infestation was recorded. The pathogen showed a poor potential of spread. At the end of the trial only 1.0% of Rhododendron and 0.3% of Viburnum were infested with P. ramorum. Typical symptoms could be observed. On Rhododendron the pathogen caused a branch dieback. Stems showed a brown discoloration, which starts usually at the tip of the twig and moved towards the base. Infected Viburnum showed a stem base rot with wilting symptoms. Additionally rhododendrons were natural infested with Phytophthora citricola. This pathogen caused the same symptoms like P. ramorum and spread much faster. Investigations of leaf litter showed that both Phytophthora species had colonized the ground. This observation and the pattern of spread indicate that inoculum on the ground has been transmitted to arial plant parts via rainsplash. There is little evidence that P. ramorum has been transmitted directly from plant to plant via splashwater or air.     

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.     

Einfluss von Pflanzenschutzmitteln einer Zuckerrüben-Spritzfolge auf biologische Aktivitäten und auf den Abbau von Chloridazon im Boden. II. Gefäss-und Laborversuche

Effect of carious pesticides of a sugar-fact spray programme on biological activities and chloridazon degradation in soil. II Pot trials and laboratory experiments In pot trials and laboratory experiments degradation and plant availability of Chloridazon (Pyramin) in soil, applied alone and in combination with other pesticides of a sugar-beet spray programme were investigated and also the influence of these treatments on soil dehydrogenusc activity and straw decomposition. After an initial lag-period chloridazon degradation was rapid, and obviously was unaffected by plant growth and other pesticides. The average lime for 50% decrease of the initial concentration was 10 days. The water-extractable portion of chloridazon in soil was not affected by the presence of other pesticides and was about 43% 1 week after application and decreased to 0% during the following week. Pyramin alone did not influence straw decomposition, and the spray programme was slightly stimulatory. In pot trials with and without plains, dehydrogenase activity was not significantly inhibited by Pyramin, whereas with the spray programme and bare soil, slightly reduced enzyme activities were observed. Under laboratory conditions the spray programme was more inhibitory than Pyramin alone. There was no correlation between biological soil activities and chloridazon degradation.     

Der Zusammenhang zwischen oxidativem Stress und Blattseneszenz während der Entwicklung von Pflanzen

The final step leading to the death of an organism is the phenomenon of senescence. Senescence is a complex, highly regulated phase in the development of a plant which results in the coordinated degradation of macromolecules and mobilization of nutrients into other parts of the plant. Free radicals are thought to play an essential role in senescence, especially those derived from oxygen. These molecules are extremely toxic. The levels of the different reactive oxygen species appear to be tightly regulated. In low concentrations, hydrogen peroxide may serve as a signaling molecule. Therefore, a coordinated regulation of the free radical scavenging system is essential. This comprises enzymatic components such as catalase, superoxide dismutase, or ascorbate peroxidase, or nonenzymatic molecules such as ascorbate or glutathione. In the plant system, there are several indications that the cause of increased radical levels during senescence is not only the elevated generation of radicals but also the loss of the antioxidant capacity. This review is about the cellular processes and regulation of senescence, oxidative stress, and the reaction of the plant by activation of the antioxidative system. The correlation between oxidative stress and senescence should at last be discussed.     

Rückstände von Carbendazim und anderen Fungiziden im Bienenhonig aufgrund der Blütespritzung von Winterraps

Zusammenfassung: 91 hessische Rapshonige der Erntejahre 2000 bis 2002 wurden auf Rückstände der zur Blütespritzung zugelassenen Fungizide Carbendazim, Iprodion, Metconazol, Tebuconazol und Vinclozolin untersucht. Dabei traten Tebuconazol und Vinclozolin vereinzelt in Mengen bis max. 0,018 mg/kg auf, Carbendazim hingegen in 35,2 % aller Proben und in Gehalten von bis zu 0,118 mg/kg. Im Mai 2002 wurden zwei isoliert gelegene Rapsflächen (9,8 bzw. 5,5 ha) während der Vollblüte mit 1 l/ha Derosal^® (360 g/l Carbendazim) bzw. mit 1,5 l/ha Folicur^® (251,2 g/l Tebuconazol) gespritzt. In jeweils sechs Honigproben von unmittelbar an den Flächen aufgestellten Völkern wurden Rückstandsgehalte von durchschnittlich 0,145 mg/kg (0,061 – 0,227 mg/kg) Carbendazim bzw. 0,018 mg/kg (<BG – 0,025 mg/kg) Tebuconazol ermittelt. Wirkstoffspezifische Eigenschaften des Carbendazims führen offensichtlich zu außergewöhnlich hohen Belastungswerten im Honig. Ungeachtet ihrer toxikologischen Relevanz veranlassten diese Befunde die Herstellerfirmen zu einer zwischenzeitlichen Vertriebseinstellung von Carbendazim und Thiopanatemethyl auf dem deutschen Markt.

---

Residues of Carbendazim and other fungicides in honey due to blossom application in canola

Summary: During 2000 to 2002, 91 Hessian spring honeys from regions with an extended cultivation of canola were analysed for residues of the registered fungicides Carbendazim, Iprodion, Metconazol, Tebuconazol and Vinclozolin. The samples included 15 honeys from certified ecological apiaries.While Iprodion and Metconazol were not detected at all and Tebuconazol and Vinclozolin only sporadic with maximum levels of 0,018 mg/kg, Carbendazim was found in 35,2 % of the samples with up to 0,118 mg/kg. The eco honeys did not differ from the other samples.In May 2002 two isolated canola fields (9,8 resp. 5,5 ha) were treated with 1 l/ha Derosal^® (active in gredient: 360 g/l Carbendazim) in 600 l water/ha resp. with 1,5 l/ha Folicur^® (active ingredient: 251,2 g/l Tebuconazol) in 400 l water/ha during full blossom while a third field served as an untreated control. Three honey bee colonies were placed close to each field four days before treatment. From each hive, two samples of fresh honey were taken seven days after the treatment and analysed for residues of Carbendazim and Tebuconazol. While only one of six samples from the control field was contaminated with 0,080 mg/kg Carbendazim, each of the six honey samples from the Carbendazim treated field showed residues of Carbendazim (average: 0,145 mg/kg, range: 0,061 – 0,227 mg/kg) and five of six samples from the Tebuconazol treated field were positive for Tebuconazol (average: 0,018 mg/kg, range: <DL – 0,025 mg/kg).Due to its specific characters (slightly hydrophilic compared to other fungicides) a blossom application of Carbendazim can result in extremely high residue levels in honey. In the meantime, the manufacturers of Carbendazim and Thiophanatemethyl acknowledged these findings and, irrespectively of its toxicological relevance, stopped their deal with such products on the German market.