Browsing by Subject "Apfelanbau"

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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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    Strategien zur Regulierung des Fruchtschalenwicklers Adoxophyes orana F.v.R. (Lepidoptera: Tortricidae) mit Kombinationen des Neem-Präparates NeemAzal-T/S und Entomopathogenen
    (2002) Kumpmann, Sophia Katharina; Zebitz, Claus P. W.
    The summer fruit tortrix moth Adoxophyes orana F.v.R. is known as a serious pest in pome fruits in Central Europe. According the new laws on plant protection in Germany, only few registered products are left which may be used in organic and conventional farming at present. The registered products used in organic farming base on the specific Adoxophyes orana granulovirus (AoGV; tradename: Capex) and Bacillus thuringiensis (Bt). The application of Capex in order to reduce high population densities led to various results, some of which proved to be insufficient. The results of Bt application were not satisfying, either. The application of 3 l/ha NeemAzal-T/S, a product based on Neem (Azadirachta indica A. Juss.) -extracts and plant oil, for aphid control in apple orchards shows promising side effects on Adoxophyes orana with a mortality rate of about 60 - 70%. However, the efficacy of the recommended dose of 3 l/ha at red bud stage is not high enough to obtain a satisfying control of A. orana in orchards with medium and high population densities. A possible positive aspect may be the long-term effect upon the population of A. orana following the application of both, Capex or NeemAzal-T/S. Until now, however, long-term effects have not been considered in control strategies. Thus, this study aimed towards to take advantage of these side effects of the application of NeemAzal-T/S in combination strategies with Bacillus thuringiensis or Capex for efficient and economically interesting control of this pest. Field and laboratory tests were carried out to test different strategies of combinations including short-term and long-term effects of the products. In addition, the aim of some laboratory trials was to test appropriate Bt-products and further additives for A. orana regulation. Combination of NeemAzal-T/S and a Bt-product In laboratory trials and field tests, different concentrations of NeemAzal-T/S and Bt were combined and sprayed at the same time to assess the effects of this strategy on the larvae of A. orana. This combination showed neither additive nor synergistic effects, no matter the concentration used. A successive strategy with a first application of NeemAzal-T/S either with or without adding 0,4 kg/ha Bt and with a second application of 0.6 ? 1.0 kg/ha Bt lead to high efficacy. Application of NeemAzal-T/S ? in doses of 2 l/ha or 3 l/ha in the first treatment ? turned out to be an important factor to achieve a good result. The addition of 0.4 kg/ha Bt to the first application did neither show a better nor a worse result. Obviously, this successive combination strategy leads to lower negative influence of the feeding inhibition, which seems to be partly responsible for the negative effects on A. orana when both products were applied at the same time. Combination of NeemAzal-T/S and Capex In organic farming, Capex at 100 ml/ha is applied two times in spring. Aim of the following tests was to minimise the risk of failure of a treatment with Capex by taking advantage of the positive side effects of the application of NeemAzal-T/S and to find out whether a reduction of the amount of Capex may be possible in this combination. In laboratory trials, no synergistic effects of a combined application of both products could be observed. In fields, Capex applications leading to 50 ? 60 % efficiency could be raised to 81 ? 94% by adding of NeemAzal-T/S. When Capex applications led to a larval mortality rate of 90% or more, the addition of NeemAzal-T/S showed no effects. Furthermore, the long-term effects of the combination of NeemAzal-T/S and Capex were taken into account. One trial showed that the increased efficiency of the combination was higher when considering also the number of larvae of the subsequent two generations, than assessing the larval mortality rate in the treated generation only. This leads to the conclusion that either the long-term effect of NeemAzal-T/S alone or of both products together reduces the population density of A. orana in the generations following the treatment. Long-term effects of Capex Aim of this part of the studies was to estimate whether an application of a small amount of Capex in summer in addition to the usual spraying in spring leads to a higher infection potential in the orchard. With the additional treatment, the rate of infected larvae in summer could be increased from 8% to 22%, and the amout of damaged fruits from 0.2 % to 0.6%. But both infestation rates were very low and, thus, too weak to support any interpretation. Thus, the additional treatment in the summer turned out to be of economical advantage. The repeated use of this virus product in various concentrations and against various generations of A. orana seems to be a very promising strategy. It remains to further research and long-term studies to elucidate the most efficient sequence, amount and dates of application of the virus to obtain maximum control of A. orana.