Search

Wie ware es mit einem Apfel-Birne-Hybrid? Auf der Suche nach Elternsorten, die die Kombinationen guter Eigenschaften wie ausgeglichenes Zucker/Saure-Verhaltnis, besonderes Aroma, ansprechende Fruchtfarbe, angenehme Fruchttextur und gute Anbaueigenschaften ergeben, liegt fur Kernobstzuchter der Gedanke nahe, auch die Birne als Kreuzungspartner zu verwenden. Sie hat ein besonderes Aroma, eine charakteristische Fruchtform und andere Eigenschaften im Anbau als der Apfel.

[no abstract]

The organic market has grown exponentially in Europe during the last ten years. However, the organic fruit industry in European states still has a relatively low market share of less than 1-5% compared with organic vegetables, milk and eggs that have achieved market shares of close to 10% of the total market. As well, conventional fruit growers still hesitate to respond to the generally good organic market demand. A major reason for this behaviour is the continuing high production risk due to less availability of effective management tools for the control of pests, diseases, weed and biennial bearing. The key pests and diseases in apple and pear include scab, sooty blotch, and fire blight as well as rosy apple aphid, pear sucker and codling moth, as well as post-harvest diseases like Gloeosporium rot. Another reason that holds up organic fruit expansion is that in fruit production, in contrast to milk or wheat, new and organic-specific marketing attempts are necessary for organic cultivars, less cosmetic “beauty”, etc.) but are presently scarce. In an ideal organic production system, all possible measures that lead to improved stability and self-regulation of the agro-ecological system have to be implemented (e.g. resistant cultivars, bio-diversity areas, lower planting densities, measures to avoid inoculum build-up, soil fertility). At present, most organic orchards have almost the same design as found in conventional production and often do not include system stabilising elements. Therefore, organic fruit production still depends largely on direct pest and disease control methods. In the last decade effective compounds and techniques have been developed such as Neem preparations, granulosis viruses, and mating disruption to control pests. Some new plant protection techniques e.g. clay powders, resistance inducers, better spray technique and spray timing models have been introduced. The introduction of new equipment, compounds, cultivars and decision support systems will further improve yield stability. However, for other limiting factors, such as weed competition, crop load regulation and market demands in respect to quality, innovative solutions have to be developed. The challenge for the future is to build up a credible (“true-organic”) and high quality multi-factor oriented organic fruit production that combines single factor solutions to a self-regulating, and possibly even organic pesticide-free, production system. Progress in this direction will lead to innovative organic production and marketing concepts that are clearly different from conventional ones. To achieve these goals, creative efforts along the whole chain involving producers, consumers, retailers, advisory services and researchers are essential.

The pear leaf blister mite Eriophyes pyri (Pagenstecher) causes severe damage to pear leaves and fruits. As mites are well sheltered from exposure to plant protection agents during summer and acaricide efficacy is reduced when temperatures are low in early spring, autumn acaricide applications were evaluated to control mites as they migrate to their hibernation sites. Post-harvest sulphur and mineral oil treatments were applied in September 2003 and mites were monitored in the following spring. Only the sulphur treated trees were virtually free of blisters. Sulphur treatments showed an efficacy of 95.3% (one application) to 99.6% (three applications), whereas, mineral oil treatments only had an efficacy of 12.8% (one application) to 69.6% (three applications). That post harvest sulphur applications could decontaminate heavily infested orchards was possible was confirmed by a large-plot trial in two orchards in 2004/2005.

Die Bedeutung phenolischer Inhaltsstoffe, ihre Rolle als Resistenzfaktoren und die Beeinflussung ihrer Biosynthese durch verschiedenste exogene und endogene Faktoren wurden im Rahmen der vorliegenden Arbeit an Birnenpflanzen untersucht. Dabei zeigte sich, dass die Phenylpropanoidbiosynthese von Birne abhängig von dem Genotyp und der Blattentwicklung, sowohl auf eine Infektion mit dem Feuerbranderreger Erwinia amylovora als auch auf eine Behandlung mit dem Wachstumsregulator Prohexadion-Ca (Regalis) reagiert. Desweiteren konnte in den Experimenten belegt werden, dass Prohexadion-Ca der einzige Einflussfaktor ist, welcher aufgrund einer kompetitiven Hemmung eines Schlüsselenzyms neben den quantitativen Modifikationen im Phenylpropanoidstoffwechsel auch qualitative Veränderungen bewirkt. Diese normalerweise nicht in Birnenblättern vorkommenden neuartigen Metabolite wurden als das 3-Deoxyflavonoid Luteoliflavan und das Flavanon Eriodictyol 7-glukosid identifiziert. The meaning of phenolic compounds, their role in resistance and the influence to their biosynthesis by different exogenic and endogenic factors was investigated in this work with pear plants. Dependent on the cultivar and the leaf development, it was shown that the phenylpropanoid metabolism of pear react to infection by the fire blight pathogen Erwinia amylovora as well as to a treatment with the growth regulator prohexadione-Ca (Regalis). In addition it was observed, that due to a competitive inhibition of a key enzyme, prohexadione-Ca is the only influencing factor which causes quantitative and qualitative modifications in the biosynthesis of phenylpropanoids. These novel metabolites, which are normally not synthesised in pear leaves, were identified as the 3-deoxyflavonoid luteoliflavan and the flavanone eriodictyol 7-glucoside.

Application of processed kaolin particle film repels insects without lethal effects; hence side effects on beneficial arthropods are low. Processed kaolin may be an alternative to broad-spectrum insecticides used against European pear sucker, Cacopsylla pyri (L.), in organic and conventional pear production. Trials showed that the processed kaolin showed a very high efficacy, and the population of C. pyri was kept under a damaging level over the whole season. In conclusion, kaolin shows promise as an alternative control for C. pyri in organic and orchards of Integreted Pest Management.