Vergleich von Nachweismethoden für Kartoffelzystennematoden (Globodera spp.) im Hinblick auf eine Qualitätssicherung von Diagnosen geregelter Schadorganismen

Testing for PCN is indispensable in EC seed potato production, to avoid a further spread or introduction of this pest. Till now methods for sampling and detection are varying between member states and even within Germany. Therefore in order to obtain comparable results within a new PCN directive the procedure will be regulated by EPPO standard diagnostic protocols, like it is the case for testing Globodera spp. resistance of potato varieties. The Bavarian plant protection service hopes, that beside cyst extraction by flotation the bioassay will be part of the new EPPO standard. The bioassy – in contrast to PCR methods – is well established and allows a reliable discrimination not only of PCN species but also of races and pathotypes. Results of a long-time survey demonstrate clearly, that bioassay and cyst extraction yield comparable results provided quality assurance criteria are met.     

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.     

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.     

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.     

Zur Wirkung von Verbenon auf den Buchdrucker,Ips typographus L. (Col., Scolytidae)

Eine Verdunstungsrate von 93 mg/Baum/Tag aus 24 Polyethylen-Dispensern von je 50 cm Länge und mit 10 ml Verbenon gefüllt, verhinderte nicht den Befall der verbenonbehandelten lebenden Fichten durch Buchdrucker, obwohl pheropraxbeköderte Schlitzfallen in nur 6 m Entfernung (d. i. die Hälfte des praxisüblichen Sicherheitsabstandes) standen. Im Gegenteil, alle 6 verbenonbehandelten Fichten wurden besiedelt, 5 von ihnen innerhalb von 2 Tagen nach Applikation der Verbenondispenser, wogegen nur 2 der ebenfalls in 6 m Entfernung stehenden unbehandelten Kontrollfichten ganz schwach (1 bzw. 2. Einbohrungen) nach 10 Tagen befallen wurden. An den Verbenonfichten reichte die Zone der Einbohrlöcher (4–38 je Baum) nicht wesentlich über 3 m hinaus, d. i. etwa die obere Grenze der Verbenon-Zone, die 0,5m über dem Boden beganri. Die Käfer hatten sich dicht neben und sogar unter den Dispensern eingebohrt. Diese Befunde deuten an, daß Verbenon in Kombination mit flüchtigen Wirtsbauminhaltsstoffen eine gewisse Attraktivität für Buchdrucker besitzt.In zusätzlichen Experimenten (Rotation mit Schlitzfallen) konnte sichergestellt werden, daß die hier verwendete Verbenoncharge die übliche antiaggregative Eigenschaft hat (die mit diesem Verbenon beköderten Fallen erbrachten nur 2% des Fanges der ausschließlich mit Pheroprax^R beköderten Vergleichsfallen). Schlitzfallen mit Pheroprax^R plus Verbenon können aber auch sehr viel mehr Buchdrucker fangen, nämlich wenn sie inmitten einer Anzahl von in der Nähe befindlichen, nur mit Pheroprax^R beköderten Fallen stehen (40–60% von deren Fängen, z. B. innerhalb einer kreuzförmigen Anordnung mit Abständen von 2 m zwischen den Fallen).     

Untersuchungen zum endophytischen Befall von Fusarium proliferatum (Matsushima) Nirenberg in geernteten Stangen von Spargel (Asparagus officinalis L.)

Zusammenfassung Erstmalig wurden mit den vorliegenden Untersuchungen Spargelstangen zur Haupterntezeit auf endophytischen Pilzbefall untersucht. Sie zeigen, dass im Ernteprodukt zwar Fusarium proliferatum als potenzieller Mykotoxinbildner zu finden ist. Eine mögliche natürliche Kontamination mit Fumonisinen bestätigte sich nicht. Von den mit F. proliferatum infizierten Stangen wies nur eine Stange mit grau-rosa-orange farbenen Gewebeveränderungen an der Basis sichtbare Symptome auf. Allgemeine Rückschlüsse auf eine mögliche Gefährdung oder Nichtgefährdung des Verbrauchers beim Verzehr von mit F. proliferatum kontaminierten, symptomlosen Stangen können aus der Analyse nicht gezogen werden. Hierzu müssen weitergehende Untersuchungen zur Wirt-Pathogen-Interaktion erfolgen und die phänotypischen und genotypischen Einflussfaktoren in diesem Prozess noch näher untersucht werden.     

Untersuchung von Herbizidschäden im österreichischen Weinbau

Up to 2006 the majority of Austrian winegrowers have renounced the use of herbicides in viticulture according to the ÖPUL (Austria's programme for the promotion of an agriculture which is appropriate to the environment, extensive and protective of natural habitats) guidelines. According to the new agrarian environmental programme 2007 this measure is no longer subsidized. It seems very likely that a greater portion of Austrian winegrowers will be inclined to apply herbicides again, partly due to the fact that subsidies are not paid any longer and partly due to structural changes, such as the increase in average size of individual farms and thus the primary need of saving and/or minimizing working time, which have taken place in the last years. The occurrence of damage on vines and problems with identification gave reason to an examination of driftage damage caused by applications of the most commonly used substances in viticulture and agriculture by the binding and point treatment spraying techniques. Active substances, which were examined, are glyphosat, glufosinat, oxyflurofen, amitrol/diuron and the sulfonylurea flazasulfuron. The spraying agent was applied under windy conditions in order to achieve drift. So, different symptoms, such as leaf distortion, bleaching, poor fruit set and necroses could be observed.     

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.     

Untersuchungen zur biologischen Kontrolle von Schaben mit entomopathogenen Nematoden

Zusammenfassung In Käfigversuchen wurde gezeigt, dass der Nematode Steinernema carpocapsae die Australische Großschabe Periplaneta australasiae infiziert und zum Absterben bringt. Mortalitäten von 50–86% konnten erzielt werden. Dabei wurden verschiedene Köderstationen untersucht. Die höchste Mortalität von 86% wurde in Kleinkäfigen bei Verwendung einer Petrischale als Köderstation erreicht. Die Mortalität in Großkäfigen mit größeren und praxisorientierten Stationen betrug nur 50%. Als Lockmittel für die Köderstation wurden verschiedene Lock- und Futterstoffe geprüft. Die Lockwirkung von Kaffeepulver und Banane war vergleichbar mit der Lockwirkung von handelsüblichen Schabenfallen. Banane wurde zudem bevorzugt als Nahrung aufgenommen. Die Mortalität der Schaben stieg in Abhängigkeit von der Aufenthaltsdauer im Nematodengel von 80% bei 2 min auf 95% nach 30 min. Die Anzahl der Nematoden auf dem Schabenkörper sank dagegen von 431 Nematoden nach 10-minütigem Kontakt mit dem Nematodengel und direkt anschließender Zählung auf 147 Nematoden nach 10-minütigem Kontakt und Zählung nach 24 h. Die Vermutung, dass die Nematoden über die Stigmen eindringen, wird unterstützt durch die vergleichsweise hohe Mortalität von 83% bei Applikation der Nematoden an den Körperseiten von Thorax und Abdomen gegenüber den Mortalitäten bei Auftragung an anderen Körperstellen (65% Behandlung dorsal, Anus 38%, Behandlung ventral 33%, Caput 25%).     

Validierung der Extraktion von Nematodenzysten aus Bodenproben mit dem MEKU-Bodenextraktor

The diagnosis of phytopathogenic agents has to be justiciable. Quality management gains increasing importance. In preparation of accreditation of the diagnostic laboratory at the Agricultural Public Service Center Rheinhessen-Nahe-Hunsrück in Bad Kreuznach the extraction of cyst nematodes from soil samples by means of a MEKU-soil extractor was validated according to the principles of the German Accreditation Association (DAkkS). The results achieved with test procedure were analyzed according to the parameters analytical sensitivity, analytical specification, selectivity, repeatability and reproducibility. The limit of acceptance kept the conditions of the quality control plan. Therefore the test procedure is qualified for diagnosis of quarantine organisms according to the specifications of DAkkS. Continuous participation in laboratory comparative tests ensures a long term, high level quality standard.     

Weißeln von Obstbäumen zur Vermeidung von Frostrissen und Stamminfektionen mit Pseudomonas syringae

Painting the trunks of deciduous fruit trees white prevents frost injuries. Frost cracks in the bark are important entry sites to the trunk for many plant pathogens such as Pseudomonas syringae, which causes decline of fruit trees. Frost damage and the epiphytic Pseudomonas population on trunks were significantly reduced by painting trees with white paint before the first frost in autumn. A copper compound (Funguran) was added to the paint. This sort of protection from frost injuries relies primarily on the physical effect that the sunlight does not warm the bark, since it is reflected by the white colour. Heating up the bark on the sunny side of the trunk during frost periods leads to tension cracks. A number of products were tested for their stability on bark and their ability to cover trunks and reflect sunlight. Some colours were stable for the whole observation period (more than 100 days) and guaranteed effective heat protection. In conclusion, painting the trunks of deciduous fruit trees white effectively controlled frost cracks. Moreover, the results of a 2-year field trial indicate that trunk infections of Pseudomonas syringae were prevented by using a white paint to which a copper compound was added.