Browsing by Subject "Pflanzenschutz"

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    Applikationstechnische Untersuchungen im Weinbau an Pflanzenschutzgeräten mit Einrichtungen zur Rückführung nicht angelagerter Spritzflüssigkeit
    (1990) Kleinlagel, Bernd; Kutzbach, Heinz Dieter
    Zur Verringerung der Umweltbelastung bei Pflanzenschutzmaßnahmen sind u.a. technische Weiterentwicklungen der Pflanzenschutzgeräte notwendig. Die erst seit kurzer Zeit im deutschen Weinbau anzutreffenden Pflanzenschutzgeräte mit Einrichtungen zur Rückführung nicht angelagerter Spritzflüssigkeit, kurz Recyclinggeräte genannt, versprechen neben einer deutlichen Reduzierung von Abdrift und Bodensedimentation der Pflanzenschutzmittel auch eine Verbesserung der Wirtschaftlichkeit durch Wiederverwendung der nicht zur Anlagerung gelangten Spritzflüssigkeit. Die unter Laborbedingungen durchgeführten Versuche zur Bestimmung der Auffangraten liefern grundlegende Daten zu den verschiedenen technischen Lösungen. Ziel der unter praxisüblichen Bedingungen durchgeführten Freilanduntersuchungen war es, aufzuzeigen, inwieweit diese neue Applikationstechnik Spritzmittelverluste mindert und dennoch eine qualitativ und quantitativ ausreichende Wirkstoffanlagerung auf den Rebblättern ermöglicht.
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    Bericht des Ausschusses der Versuchsstation über die Tätigkeit im Jahr 2007
    (2008) Versuchsstation für Pflanzenbau und Pflanzenschutz
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    Biofector Herbarium Raupp
    (2020) Hartman, Peter; Raupp, Manfred G.
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    Characterisation of the sensitivity of Zymoseptoria tritici to demethylation inhibitors in Europe
    (2021) Huf, Anna; Vögele, Ralf
    The fungal pathogen Zymoseptoria tritici (formerly Septoria tritici) causes Septoria tritici blotch (STB), one of the most yield reducing diseases of wheat worldwide. In addition to cultural control measures and the cultivation of wheat varieties with a level of disease resistance, STB control relies heavily on the application of foliar fungicides with different modes of action. The demethylation inhibitors (DMIs) have been one of the most widely applied fungicides for many decades and belong to one of the most important fungicide modes of action in STB management. DMIs inhibit the sterol 14α-demethylase, an essential enzyme in the ergosterol biosynthesis pathway, encoded by the CYP51 gene of fungi. Widespread and intensive use of the DMIs over time has led to a continuous negative shift in the sensitivity of Z. tritici towards DMIs that have been used for a long time. This shift in sensitivity is mainly driven by the accumulation of mutations in the CYP51 gene resulting in the selection of various CYP51 haplotypes. More recently, CYP51 overexpression and an increased efflux activity, based on the overexpression of the MFS1 transporter, have been shown to be additional mechanisms affecting DMI sensitivity of Z. tritici. Inserts in the CYP51 promotor (CYP51p) and MFS1 promotor (MFS1p) were observed to be responsible for CYP51 and MFS1 overexpression. The prevalence and contribution of different DMI resistance mechanisms to a reduced DMI sensitivity of Z. tritici were investigated in isolates from across Europe in 2016 and 2017. The CYP51 gene of all isolates was sequenced and the CYP51p and MFS1p was investigated for inserts in order to determine the character of the CYP51 haplotypes as well as to identify CYP51 overexpression or if an increased efflux activity was occurring in these isolates. Overall, it was shown that the occurrence of CYP51 haplotypes was still the most frequent and important mechanism conferring a reduction in sensitivity to DMIs by Z. tritici in Europe. Nevertheless, an increase in the frequency of isolates exerting CYP51 overexpression and those exhibiting increased efflux activity was observed compared to earlier studies. Glasshouse data demonstrated that DMIs can still contribute to disease control, and in some cases give full control, of STB even if isolates expressed CYP51 overexpression and/or an increased efflux in addition to also carrying moderately or highly adapted CYP51 haplotypes. However, in order to prevent the further increase and spread of further adapted CYP51 haplotypes plus additional resistance mechanisms in the Z. tritici population across Europe, anti-resistance-management strategies should be a high priority in the use of DMIs. In addition, especially integrated disease management strategies, such as the appropriate choice of cultivars, should be applied in order to keep STB disease pressure low and consequently reduce the number of fungicide applications. Moreover, resistance-management strategies may exploit the limited cross-resistance between different DMIs, for example, by the use of mixtures or alternation of different DMI fungicides. However, control strategies should also incorporate the use of fungicides with different MOAs. The aim of all these strategies is to reduce selection of adapted Z. tritici isolates and consequently to prolong the efficacy of DMIs in STB management.
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    Cover cropping in integrated weed management
    (2018) Sturm, Dominic; Gerhards, Roland
    Weed control constitutes a major challenge in the worldwide crop production. Beside chemical and mechanical weed control strategies, cover cropping provides an effective way of biological weed suppression. Five different field experiments were conducted at six locations from 2014-2016 to evaluate the weed control efficacy of different cover crops in mono and mixed cultivation combined with different fertilization strategies and sowing dates. Furthermore weed suppressing effects of cover crop mulches in spring and of living mulches in summer were investigated. Potential effects on sugar beet emergence, quality and quantity were also assessed. In three laboratory and two greenhouse experiments from 2015-2017, the proportional contribution of competitive and biochemical effects on the overall weed suppression and the identification of varying susceptibilities of different weeds against biochemical stresses were at the center of research. In field experiments, the weed suppressive effects of cover crops and living mulches in mono and mixed cultivation were tested. The experiments emphasized the importance of cover crop and living mulch mixtures compared to mono cropping due to a higher flexibility to biotic and abiotic stresses. This was followed by a more constant biomass production and more effective weed suppression. Moreover, the observed weed control was a result of competitive and biochemical effects, induced by cover crops. These were later on analyzed for active weed growth suppressing compounds. Altering cover crop sowing date and fertilization to optimize the weed control resulted in significant changes of cover crop and weed biomass. Early cover crop sowing five or three weeks before winter wheat harvest increased the weed control efficacy in one year, significantly. Due to contrary results over the two experimental years, we suggest that the cover crop biomass and consequently the weed suppressive ability depends on sufficient soil water for rapid cover crop germination and growth. The use of cover crop mulch in sugar beet crops provided a weed suppression of up to 83%. Especially mulch derived from cover crop mixtures reduced the weed density (56%) more effectively compared to mono cultivated cover crops (31%). The inclusion of cover crops, mulches and living mulches can lead to significant herbicide reductions in the main crop. However supplementary mechanical or chemical weed control strategies are still necessary, especially in crops with a low competitive ability like sugar beets. Nevertheless, novel mechanical weed control approaches and adequate herbicide application techniques, as band-spraying, can reduce the herbicide input in the long-term. Germination tests with aqueous cover crop extracts were conducted on weed seeds to evaluate differences in the inhibition of germination and root growth. Furthermore, different sensitivities of the weeds against the different cover crop extracts were revealed. Some cover crops as S. alba, F. esculentum, H. annuus, T. subterraneum and L. usitatissimum showed the most effective weed suppression. Moreover, the weed M. chamomilla showed the highest susceptibility against biochemical stresses in the germination tests. A strong positive correlation between the weed suppressive effects by the extracts and the field weed suppression was found. This indicated that biochemical effects play also an important role on the overall weed suppression in the field. To estimate the proportions of competitive and biochemical effects on the overall weed suppression by cover crops, greenhouse experiments with active carbon supplemented soil were conducted. These experiments revealed that biochemical effects, by the presence of active carbon in the soil, shifted the balance of competition between cover crops and weeds. In the course of the experiments, we also found species-specific effects on the donor as well as on the receiver side. The results of this thesis demonstrate the diverse use of cover crops, their mulches and living mulches in agricultural systems. This work aims on the optimization of biological weed control strategies and indicates approaches for future research. It is for example not yet clear how cover crops suppress specific weeds and if it is possible to design combinations of specific cover crops for the suppression of individual weed communities. Additionally, these results help to reduce long-term herbicide inputs in agricultural systems.
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    Entwicklung der Zufriedenheit der Landmaschinenhändler mit den Herstellern
    (2015) Becker, Tilman; Semenenko, Ksenia
    Bereits im April/Mai 2006 und im April/Mai 2008 wurde die Zufriedenheit der Landmaschinenhändler mit ihren Herstellern im Rahmen einer schriftlichen Befragung abgefragt. Eine Online-Befragung erfolgte dann im April/Mai 2015. Insgesamt nahmen 160 Händler an der Befragung teil. Wie 2006 und 2008 wurde auch 2015 die Bewertung der Händler zu fünf unterschiedlichen Kategorien abgefragt: - Traktoren - Mähdrescher - Futtererntetechnik - Bodenbearbeitung und Saat - Technik für Pflanzenschutz und Düngung. Abgefragt wurden z.B.: - Gesamtzufriedenheit mit jeweiligem Hauptlieferanten - Zufriedenheit mit einzelnen Marketingmaßnahmen im Detail Die Marketingmaßnahmen umfassen z.B. die Bereiche: - Produktprogramm - Zukunft der Lieferanten im Wettbewerb - Beziehung zu Lieferanten. Die Gesamtzufriedenheit setzt sich aus der Zufriedenheit in den einzelnen Bereichen zusammen. Um die Bedeutung einzelner Bereiche für die Gesamtzufriedenheit zu bewerten, wurde der Korrelationskoeffizient zwischen der Gesamtzufriedenheit und dem jeweiligen Bereich berechnet. Zusammenfassend kann man einen zumindest leichten Anstieg bei der Gesamtzufriedenheit feststellen. Lediglich in der Produktgruppe der Mähdrescher kam es zu einer insgesamt schlechteren Bewertung als 2006. Bezogen auf alle Beurteilungen konnte die Futtererntetechnik wie schon in den Vorjahren am besten abschneiden.
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    Entwicklung innovativer Pflanzenschutzprodukte und -verfahren als umweltfreundliche Alternativen zur Bekämpfung von Mehltaupilzen : Bericht im Rahmen des Forschungsprojektes: „Silizium als Aktivator bei Kulturpflanzen“
    (2019) Raupp, Manfred G.; Weinmann, Markus; Arbeitsgemeinschaft industrieller Forschungsvereinigungen „Otto von Guericke“ e. V. (AiF) Projekt GmbH, Berlin; Madora GmbH, Lörrach; Römheld, Volker; Neumann, Günter; Blaich, Rolf; Merkt, Nikolaus
    Powdery mildews are among the most important diseases in many crop plants. In all sectors of crop production (agriculture, viticulture, horticulture and orchards) powdery mildew fungi can cause severe damage under field as well as greenhouse conditions. Although organic synthetic fungicides have been used to combat powdery mildews in conventional and integrated agriculture for decades, organic farming lacks effective alternatives to the ecologically questionable sulfur fungicides. Yet, also for integrated or conventional crop production, alternatives or supplements for a reduction and more effective use of synthetic fungicides would be desirable to optimize the production of high quality food with the help of environmentally friendly means. Objective of the present work was the development of innovative crop protection products and application strategies to combat powdery mildew fungi with respect to the knowledge on resistance-enhancing effects of an improved silicon (Si), manganese (Mn) and zinc (Zn) supply to the plants. Furthermore, various plant extracts have recently received renewed attention. Among other active natural agents, garlic (Allium sativum L.) is known for its fungitoxic effect and at the same time high Mn and Zn contents. With the present work, an overview of possible approaches to control powdery mildew in grapevine by use of Si, Mn, Zn and plant extracts from garlic has been elaborated in greenhouse experiments. In this regard, the physiological significance of Si, Mn and Zn for the expression and strengthening of plant own resistance mechanisms was distinguished from the effectiveness of spray applications for forming passive silicate crusts as mechanical infection barriers. The physiological Si status of the plants could be clearly improved only by soil rather than foliar application of silicates. Regarding the soil application of silicates, however, no practical applications are known, how silicon fertilizers can be distributed under field conditions in the soil and brought into the rhizosphere to continuously ensure high rates of Si uptake. There is also still considerable uncertainty whether the soil application of silicates in non-Si accumulators, such as grapevines, can result in sufficient Si uptake for an effective expression of resistance mechanisms. The most impressive effects in the control of powdery mildew were achieved with the spray application of potassium silicate in combination with wetting agents to form silicate crusts on the leaf surface. The positive influence of Mn and Zn on the effectiveness of spray applications of potassium silicate and the adequate compatibility of Mn and Zn chelates with potassium silicate suggest that the interactions between Si, Mn and Zn should be considered for further product development. The application of garlic extract did not result in sufficient efficiency, although protective and curative properties could be observed. Allicin, supposed to be the active ingredient of garlic extract, has a broad spectrum of antimicrobial activity and is one of the few agents for which no development of resistance has been found in microorganisms so far. Therefore, the interest in this agent for the development of biological plant protection products is expected to increase.
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    Epidemiologie des Esca-Erregers Phaeomoniella chlamydospora und eine neue Bekämpfungsmöglichkeit mittels eines Wundverschlusses aus elektrogesponnenen Polymeren
    (2018) Molnar, Melanie; Vögele, Ralf
    Esca disease has become a global thread for viticulture over the last decades. It is caused by a complex of at least three different wood-inhabitating fungi Phaeomoniella chlamydospora (Pch), Phaeoacremonium aleophilum (Pal), und Fomitiporia mediterranea (Fmed). For all these fungi wounds in wood are seen as the main entrance way, especially pruning wounds, which are caused by winter pruning. Currently, there are no effective control mechanisms available Therefore, it was the main aim of this project to test a new wound closure made of electrospun fibers, which shall be applied on the pruning wounds to build a physical barrier against invading spores. For evaluating the effectiveness of this treatment the epidemiology of the fungus Pch was investigated, as this fungus is one of the first of this complex invading the vine. For this purpose new molecular techniques have been developed to identify and differentiate Pch reliably. For epidemiologic studies the focus was placed on the occurrence of spores of Pch in the vineyards during the year. Spore traps were placed in vineyards of the Julius Kühn-Intitute which were showing severe symptoms of Esca and in vineyards which were free of foliar symptoms. Traps were analyzed during the whole three year project period on a weekly basis. In this study a new method was developed using a Pch- specific Nested-PCR (polymerase chain reaction) to analyze the spore traps instead of the usual method, in which the trapped spores are spread on media and counting germinated spores. The new Nested-PCR turned out to be a very fast, reliable and sensitive method. It was the first time Pch could be detected in a German vineyard year round. Spores of this fungus could be detected over the whole trial period. Furthermore, a collection of 16 Pch strains with origins from Germany, Italy and South Africa was analyzed using a set of 17 RAMS (random amplified microsatellites) primer to link each one with a unique haplotype. By using this method some polymorphisms formed a pattern which could be interpreted as length polymorphisms. Further analyses of the sequences showed that there are in fact length polymorphisms which are based on repeats of the same sequence. The combination of RAMS primers and the sequence analysis resulted in a finer differentiation of isolates. Primers were developed flanking these repetitive sequences to detect polymorphisms directly without a previous RAMS-analysis. In the end ten haplotypes and two clusters each containing three isolates were found. However, it was not possible to link haplotypes to their geographical origin to gain knowledge of the spread of the fungus. Markers found using the RAMS-analysis were used to differentiate the fungal spores trapped in the spore traps. Furthermore, spores were also compared with strains found in vines of the same vineyard to verify, if the spores were possibly released by fungi in the plants or if they had a different source. This direct analysis was successful in first trials and proofed the existence of different strains in the traps. For an exact classification more markers and primer pairs have to be developed suitable for analyzing spore traps. The epidemiologic survey of this pathogen clearly shows the necessity of a good working wound closure which has to be applied directly after pruning, as the spores are present all year round and especially at the time of winter pruning. For this purpose, different electrospun fibermats made of different fibers of lactic acid were tested under laboratory conditions and in greenhouses for their impermeableness against spores of Pch. During these tightness tests in the greenhouse the new developed Nested-PCR was used to exclude, within the scope of its detection limits, an already exiting infection of the tested plants and to confirm that the a new infection was caused by the applied strain of Pch. Furthermore the degradation and aging of the materials was tested under laboratory and field conditions. Fiber mats with an added amount of glycolic acid turned out to be less stable. Among the different materials fiber mats based on pure lactic acid turned out to be principally suitable to build an applicable and efficient wound closure. First trials in the vineyard confirmed this positive result. However, the long term effect of this treatment on the incidence of Esca disease in vineyards has to be proven.
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    Evaluating different management strategies to increase the effectiveness of winter cover crops as an integrated weed management measure
    (2020) Schappert, Alexandra; Gerhards, Roland
    Weed control in agricultural production systems is indispensable to achieve stable crop yields. Integrated cropping systems are demanding for preventive and ecologically harmless weed control measures in order to protect soil and water resources and to retard the selection of herbicide-resistant weeds. Well-established winter cover crops provide nutrient retention and soil protection and may effectively suppress weeds. This contributes to reduce chemical and mechanical fall- and spring-applied weed control practices. However, producers are cautious towards integrating cover crops in crop rotations, as their performance is related to environmental conditions and varies, therefore, significantly from season to season. To increase their integration into cropping systems, reliability on weed control by cover crops needs to improve. In the current study, management strategies such as i) the cover crop sowing method, ii) the selection of water deficit tolerating cover crop species, iii) cover crop species combinations, iv) the adjustment of the mulching date and v) tillage practices after cover crop cultivation were considered as possibilities to improve the effectiveness of cover crops to control weeds during cultivation and in the subsequent cash crop. Within the first and the second publication, the general weed and A. myosuroides control ability of a cover crops mixture during and after cultivation were compared in the field with various fall-applied tillage methods and glyphosate treatments. Due to the development of highly competitive cover crop stands, weeds were suppressed by 98% and A. myosuroides by 100% during cultivation. Therefore, cover crops were more efficient compared to glyphosate application(s), non-inversion and inversion tillage and revealed a great potential to reduce or even replace chemical and mechanical fall-applied weed control measures. The efficient A. myosuroides control during the cover crop cultivation remained until spring barley harvest. This quantifies cover crops to complement herbicide resistance management strategies. In contrast, due to the weak cover crop performance during fall-to-winter within another two experiments included in the second article, weed suppressive effects of cover crops disappeared after the cultivation of cover crops. This might have been the reason why reduced tillage and adjusted mulching dates in spring failed in contributing to expand weed suppressive effects of cover crops in these experiments. Cover crop mixtures are attributed to show a greater resilience against unfavorable conditions than pure cover crop stands which is expected to result in an increased weed suppression ability. Within article three, the weed control efficacy of pure cover crop stands was compared with species mixtures. Pure stands of Avena strigosa Schreb. and Raphanus sativus var. oleiformis Pers. provided the most efficient weed control with 83% and 72%, respectively. Cover crop species mixtures showed a weaker weed suppression ability than the most efficient pure stand. In order to improve the weed control ability of cover crop mixtures, it was evaluated that the species selection is more relevant than the species diversity. Thereby, environmental requirements, such as water and temperature demand, and weed suppression mechanisms should be considered. Weed suppression of mixtures was improved by increasing the proportions of A. strigosa and R. sativus var. oleiformis, as they were showing a susceptibility for dry conditions and combine a strong competition for resources and allelopathic interference with weeds. Within the fourth article, it was explored whether a low susceptibility of single cover crop species to water-limitations accompanies an improved weed suppression ability. A. strigosa and Sinapis alba L. showed differing suitabilities to cope with water-deficit in the greenhouse. A relation between weed suppression and water demand of cover crops at the field was not identified. Although the weed control ability of cover crops is generally narrowed under water-limited conditions, the weed suppression potential of individual species seems to be independent of their water supply. The adjustment of the cover crop sowing method, the consideration of species-specific requirements and the mixing strategies, were evaluated as being important to improve the resilience of cover crops against severe environmental conditions and their weed control ability. Investigations of cover crop mixtures with respect to single component species, their mixing ratios and seed densities, might further increase the absolute and average effectiveness of cover crops as an integrated weed management practice.
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    Feuerbrand : Charakterisierung und Bekämpfungsmaßnahmen
    (2012) Bantleon, Georg; Vögele, Ralf
    This work provides new scientific findings on control agents for fire blight after hail and during bloom, on fire blight susceptibility of modern apple cultivars and on fire blight pathogenesis of blossom infection and of internal stem movement. Experiments were conducted in the laboratory, greenhouse and field. Leaf damages after hail are points of entry for new infections. Until now, there has been no method established for testing control agents after hail injury. In the method developed, plants were damaged and sprayed with a suspension of Erwinia amylovora. Control agents were applied 4 h after inoculation. The visual symptoms were scored. Streptomycin showed high effectivity. Of 13 agents tested, 3 showed an effectivity sufficient for practical use (Juglon, LMA und Myco-Sin). Flowers are the main point of entry for Erwinia amylovora. Control agents for fire blight were tested according to EPPO standard PP 1/166(3). The goal was to identify alternatives to the antibiotic streptomycin which won?t be available in fruit-growing in the future. Out of 20 agents tested, streptomycin always showed high effectivity as well as spray strategies involving streptomycin. Three agents were found to be potential substitutes for streptomycin (Antinfek, Juglon und LMA). Eight modern apple cultivars were tested for their fire blight susceptibility in flower tests in the climate chamber and in the field. Rewena showed low, Mairac and Pinova medium, Diwa, Gala Greenstar and Kanzi high and Wellant very high susceptibility. The results of the climate chamber and results from field trials correspond. A clear relation between the density of the inoculation suspension and symptom development in flower and shoot was found in pathogenesis experiments. All concentrations led to infections. Higher concentrations led to more severe symptoms. In another pathogenesis experiment bacteria were injected into the stems of apple trees. Stem tissue was analyzed for Erwinia amylovora using real-time PCR. Bacteria could only be found below the point of injection what favors the idea of phloem migration.
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    Grapevine Trunk Diseases : Epidemiologie und Molekulardiagnose wichtiger Esca-Erreger während der Pflanzguterzeugung
    (2018) Haag, Nicolai; Vögele, Ralf
    Esca is one of the most important grapevine trunk diseases (GTDs) worldwide. In Europe, the wood-inhabiting fungi Phaeomoniella chlamydospora (Pch), Phaeoacremonium aleophilum (Pch) and Fomitiporia mediterranea (Fmed) are considered the main causal agents of this disease. Even young vineyards and planting material can be affected by pathogens of Esca. So far, control possibilities were mainly limited to prophylactic measures, such as prevention of overly large pruning wounds, minimizing stress of affected grapevines and elimination of dead wood. By now, biological control is basically possible; its efficacy however, still remains to be fully proven under practical conditions. According to previous studies in Germany investigating the infection status of planting material, Pch is considered the most important causal agent for an early infection in grapevine nursery propagation. Based on this, the objective of the present study was to comprehensively assess the occurrence of Pch and other GTD-pathogens in grapevine wood and potential inoculum sources and to visually evaluate Esca-associated symptoms in rootstocks and scions during the propagation process including indoor working steps and the outdoor rooting phase. The results should then be used to point up possible control measures. For this purpose, from 2014 to 2016 visual ratings of Esca-associated wood symptoms were conducted on grapevine material collected from three different nurseries over the entire propagation process as well as from planting material ready for sale. Further assessments on pathogen occurrence by nested PCR and traditional culturing methods focused on rootstock material, which is more affected from experience, and were at first limited to the detection of Pch. For each year, a strong increase of wood symptoms, both in rootstocks and scions, was observed in the course of the production process. Compared to that, PCR- and culture-based detection rates of Pch in rootstock wood were considerably lower revealing a marked discrepancy between symptom incidence and the actual presence of the pathogen. Interestingly, a previously unconsidered fungus, Caophora luteo-olivacea (Clo), which is suspected to be a further GTD-pathogen, was frequently isolated from symptomatic rootstocks. Based on this observation, a multiplex nested PCR method was subsequently developed to specifically detect Pch, Clo as well as species of the Esca-relevant genus Phaeoacremonium (Pm). By using this method, Pch and Pm spp. were detected in ~9% and ~15% of tested rootstocks, respectively (average of all nurseries and years of observation), whereas detection rates of Clo were comparatively high at ~78%. This way, it was possible to harmonize previously observed discrepancies between symptom and pathogen incidence to a great extent. Regarding the occurrence of pathogens and expression of wood symptoms significant differences between nurseries were noticed at single sampling dates, in general however, infestation situations were quite similar. Further investigations were conducted to identify potential inoculum sources in the propagation process. Herefore, sampling was done from various hydration tanks, callusing media and nursery soil. In addition, spore traps were installed in nursery fields in order to monitor airborne inoculum. Samples were subsequently analysed by multiplex nested PCR and/or fungal isolation. PCR-based detections of Pch, Pm spp. and Clo were obtained from hydration tanks as well as from callusing media and air with Clo being the most common species in every respect. Furthermore, viable inoculum of Pch and Pm spp. were found in rootstock wood only, whereas Clo could be additionally isolated from hydration tanks, callusing media and nursery soil. However, isolation rates of Pch, Clo and Pm spp. respectively corresponded to only ~9%, ~9% and ~2% of the detection frequencies when using multiplex nested PCR. The present study allowed for a comprehensive and in part previously unknown insight into the infestation situations of planting material regarding Pch and further Esca-associated pathogens. It provides specific information on potential inoculum sources in grapevine nursery propagation and emphasizes the possible role of pre-infected planting in the development and spread of Esca. With respect to a targeted control of Esca and associated diseases, the obtained results provide an important basis to verify efficacy and practicabilty of existing or yet to be developed control measures.
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    Jahresbericht 2009 : Bericht des Ausschusses der Versuchsstation über die Tätigkeit im Jahr 2009
    (2010) Versuchsstation für Pflanzenbau und Pflanzenschutz
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    Jahresbericht 2010 : Bericht des Ausschusses der Versuchsstation über die Tätigkeit im Jahr 2010
    (2011) Versuchsstation für Pflanzenbau und Pflanzenschutz
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    Managing crop health by mineral nitrogen fertilization and use of different chemical nitrogen forms
    (2023) Maywald, Niels Julian; Ludewig, Uwe
    Maintaining plant health is one of the most difficult but crucial challenges in crop production to realize plants’ full genetic potential. It is lowered by a variety of abiotic and biotic stresses that are becoming more severe and unpredictable due to climate change and its consequences. In addition, the use of chemical synthetic pesticides is increasingly criticized for endangering sensitive natural resources and possible pesticide residues in food and environment. Avoiding or reducing the use of chemical synthetic plant protection products makes the control of phytopathogenic pests even more difficult. Therefore, in addition to optimizing various management measures such as tillage, sowing time, row spacing or crop rotation, mineral nitrogen (N) fertilization and the targeted application of N forms must be utilized to reduce abiotic stress factors and the infestation pressure of certain pests to ensure high yield performance. Consequently, several experiments were conducted to better understand how mineral nitrogen fertilization and forms can improve plant health by increasing plant resistance to abiotic stressors, particularly repeated drought stress and nutrient (P) deficiency, and to biotic stressors, such as relevant phytopathogenic fungi. It was found that with respect to repeated drought stress, maize plants receiving supplemental nitrogen during the recovery period after an early drought stress were better able to cope with late drought stress. In this context, N fertilization could help the plant to maintain its photosynthetic activity under drought stress. Additionally, plants repeatedly exposed to drought stress recovered faster with N fertilization due to transiently higher antioxidant levels and higher production of reactive oxygen species. A further experiment revealed that depending on the maize genotype, ammonium as a form of nitrogen has a positive effect on the availability and uptake of phosphorus compared to nitrate, depending on the maize genotype. This observation could be attributed not only to the acidifying effect on the pH of the rhizosphere, but also to the increased abundance of various phosphorus-solubilizing bacteria and arbuscular mycorrhizal fungi under ammonium nutrition. Together this could provide an enhanced P availability, which ultimately reduces plant stress and improves physiologically resistance leading to a reduction in disease risk. Nevertheless, studies revealed that high N fertilization in most cases promotes disease attack and makes the plant more susceptible to pathogens. Scrutinization of this observation indicated that N fertilization enhances infestations of biotrophic pathogens, especially in wheat, while necrotrophic fungi were attenuated. Overall, the complex relationship between plant pathogens and nitrogen nutrition appears to be highly variable due to dynamic factors such as the soil, microorganisms in the rhizosphere, environmental factors, and the host plant, making it difficult to give definite statements about the effects of nitrogen nutrition on pathogen occurrence. Thus, the form of nitrogen could be a promising way to target nitrogen fertilization against individual pathogens. With regards to the previous research, experiments on the influence of N form on pathogen infection, revealed that wheat leaves inoculated with the foliar pathogen Blumeria graminis f. sp. tritici (Bgt) were comparatively less infested when fertilized with nitrate or cyanamide compared to ammonium. After contact with the pathogen, an enhanced defense response in form of increased production of protective substances, indicated by increased concentrations of hydrogen peroxide and superoxide dismutase, and increased antioxidant potential, was detected. Further, it was observed that ammonium fertilization resulted in lower bacterial richness in the plant rhizosphere and higher fungal richness compared to nitrate supplementation. Additionally, a pronounced effect of ammonium fertilization on rootcolonization by important fungal pathogens such as Gaeumannomyces graminis var. tritici (Ggt) and Bgt was found. Regarding the experiment with maize under low P conditions, it appears that ammonium is able to promote both pathogenic and beneficial fungi in cereal crops. Thus, nitrate fertilization appears not only to suppress the occurrence of fungi, but may also promote pathogen-antagonistic bacteria, which in turn have a positive effect on fungal disease suppression.
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    Marketing and agriculture : how to be successful in the crop protection
    (2019) Raupp, Manfred G.
    From the beginning of the 1980s I worked as a marketing and sales manager of the agricultural supply industry in Eastern Europe and Central Asia. After the opening of the Iron Curtain in 1990 I was asked, beginning with the University of Prague, to teach the marketing philosophy of the Western world to students from universities of the former COMECON. The following presentation provides the basic information of these marketing seminars and should also serve as a checklist for future marketing plans in the field of crop protection.
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    Pflanzenschutzmittelrückstände im gehöselten Pollen der Honigbiene (Apis mellifera L.) : Auswirkungen einer feldrealistischen Pflanzenschutzmittelmischung auf Stockbienen und den Larvenfuttersaft
    (2017) Böhme, Franziska; Zebitz, Claus P. W.
    Pesticides are used worldwide and contaminate air, surfaces, soils and the aquifer. Non-target-organisms and non-target-plants may get into contact with pesticides di-rectly via drift or indirectly via run-off, leaching or sowing dust. Due to pollination services and bee products, the honeybee (Apis mellifera L.) is a non-target-organism of major interest for humans. On their flights around the beehive they collect water, pol-len, nectar, honeydew and tree resin. The proteins originating from the pollen are im-portant for nutrition and development of larvae and adults. Pollen is stored and fer-mented inside the hive as beebread and is made of hundreds of pollen loads of differ-ent plants collected over a longer period. Pesticide residue analyses of beebread is a common tool to estimate the contact of honeybees to pesticides in the field. However, such beebread analyses cover a larger time frame and a mixture with uncontaminated pollen will dilute the maximum residue levels of certain plant pollen. Therefore, pesti-cide analysis of bee bread is only an approximate approach to estimate the real pesti-cide exposition. Thus, pollen pellets were collected daily at three distinct sites with differences in agri-cultural intensity in Baden-Württemberg from 2012 - 2016 during the agronomic active season (spring/summer). We wanted to give detailed information on the daily contact to pesticides as well as changing pesticide frequencies and combinations throughout the season. 281 pollen pellet samples, each representing a single day, were analyzed for 282 active ingredients currently used in agricultural practice (publication 1). Huge qualitative and quantitative differences in the pesticide load between the sites were discovered. The meadow site near Göppingen was the least contaminated. In five ob-servation years only 24 different substances were found in 56 % of the samples with concentrations up to 300 µg/kg. The more intensive site in Ertingen is characterized by grains and maize for biogas plants. Only 13 % of the samples were uncontaminated, in the remaining samples 37 substances with maximal concentrations up to 1,500 µg/kg were detected. The site with the highest occurrence of crop protection was close to Heilbronn. Permanent crops such as wine and orchards shape the landscape. The high-est detected concentration was 7,178 µg/kg. All samples were contaminated with up to 58 different substances. During the five years of observation 73 different pesticides were found. Due to admis-sion regulations, there was a high likelihood to find 84 % of these substances in pollen. Twelve substances were found that are either not registered as plant protection prod-ucts or are not supposed to get in contact with bees. This indicates a need for further improvement of seed treatments and increasing awareness of flowering shrubs, field margins and pesticide drift. Concluding from the majority of concentrations and pesti-cides found, we assume no misuse of pesticides by the farmers at our three sites in the observation period, which would lead to direct intoxication. Considering LD50 values, the here detected concentrations are sub-lethal for honeybees. However, at any tested site and in most of the samples a mixture of different pesticides was found. Yet, it is not known, whether there are effects caused by a combination of different pesticides in sub-lethal concentrations when consumed chronically by honeybees. Therefore, we conducted a field experiment with free-flying honeybee colonies (publi-cation 2). Mini-hives containing about 2,500 bees and sister queens were established at the Apicultural State Institute. Queens were confined to an empty frame to receive lar-vae of known age. These bees were intended to feed on pesticides chronically in two crucial life stages. After larvae hatched from the eggs and after adults hatched from the cells they were fed a pollen-honey diet contaminated with a cocktail of twelve dif-ferent active ingredients in field-realistic concentrations. In colonies treated with a pes-ticide mixture, larval weight was higher and acini diameters of the hypopharyngeal glands of nurse bees were smaller than in the untreated control. However, brood termi-nation and adult lifespan did not differ between both groups. Despite feeding a pesti-cide cocktail chronically starting on the first day of larval being, no obvious negative side-effects in worker bees were detected. It raises the question, if nurse bees, which feed on the contaminated pollen-honey diet, produce larval food and feed larvae, serve as a filter system so that larvae would not come into contact with the pesticides. To determine the fate of pesticides originating from the pollen source, we started a queen rearing (publication 3). Frames with 24 h old larvae were hang into queenless free flying mini-hives. At the same time, the colo-nies were fed a pollen-honey diet containing a cocktail of 13 commonly used pesti-cides in high concentrations. The royal jelly (RJ) fed to the larvae by nurse bees was harvested from the queen cells and subjected to a multi-pesticide residue analysis. Sev-en substances were rediscovered in traces (76.5% of all detections were below 1 μg/kg). However, worker larvae older than three days receive a modified jelly, containing pol-len coloring the food yellowish. That is why we were wondering if contaminated pol-len might have a different effect on the food of worker larvae. Queens of free-flying mini hives were caged to receive larvae of known age. The colonies received a pollen-honey diet, contaminated with high concentrations of a pesticide mixture (publication 4, submitted). Worker jelly (WJ) was harvested on four successive days from larval age three to six and subjected to a multi-pesticide residue analysis. Pesticide concentrations increased with larval age and ranged between 2.9 and 871.0 µg/kg for the different substances and age groups. As the increase of substances in the WJ positively corre-lates with the amount of pollen grains counted in the larval food, we were able to show a direct relationship between the administered pollen in the food and the pesticide concentrations. Considering the maximum food uptake rates of a worker larvae, even the highest con-centrations found, would lead solely to sub-lethal amounts. Even for queens, who con-sume RJ not only as larvae but during their whole life would consume only sub-lethal pesticide concentrations. Especially considering the not-field realistic concentrations we chose for our experiments. Probably, the sub-lethal effects found in our first exper-iment are due to the sub-lethal concentrations worker larvae have taken up chronically during their development. Even though we did not detect acute intoxication symptoms and the concentrations in the brood food are sub-lethal, we cannot infer whether there are impairments of fitness or brood success of honeybee colonies in the long term. However, as honeybee colonies are considered as superorganisms, they are able to tol-erate stressors or the loss of individuals. Therefore, the detection of sub-lethal effects on colony-level in the field is difficult. Yet, a vast problem arises with solitary living insects, for example wild bee species, which are more prone to stressors such as pesti-cides. Solitary insects have more restricted flight and collecting areas, get into contact with pesticides in pollen directly as larvae and have almost no buffer capacities.
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    Tätigkeitsbericht 2007 / Landesanstalt für Landwirtschaftliche Chemie
    (2008) ; Landesanstalt für Landwirtschaftliche Chemie
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    Tätigkeitsbericht 2008 / Landesanstalt für Landwirtschaftliche Chemie
    (2009) ; Landesanstalt für Landwirtschaftliche Chemie
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    Tätigkeitsbericht 2009 / Landesanstalt für Landwirtschaftliche Chemie
    (2010) ; Landesanstalt für Landwirtschaftliche Chemie