Biologische Bodeneigenschaften in Obstbau- und Baumschulbetrieben bei ökologischer und integrierter Bewirtschaftung und verschiedener organischer N-Düngung

In organic farming only organic N-fertilizers are allowed. They have to be mineralized by soil biota before they become effective for the plant. There are a number of different organic N-fertilizers offered commercially in order to allow for a precise management of the N-supply to plants in organic farming. We tested the effects of the fertilizers “Vinasse” (product resulting from sugar-beet molasses), “Haarmehlpellets” (pellets of grounded pig bristles), “Rizinusschrot” (grist of Ricinus communis seeds), “Phytopearls” (from maize conversion), “Maltaflor” (malt germs and “Vinasse”), “Horndünger” (horn parings) and manure on soil respiration, soil animal feeding activity, earthworm abundance, microbial biomass and the C_mic/N_mic-ratio in tree nurseries and apple fruit production under organic vs. integrated management respectively. The investigations were part of a two year lasting project regarding yield effects and N-turnover that has already been reported in this journal (vol. 48/3: Dierend et al. 2006a, 2006b, Schacht et al. 2006). Significant differences between fertilized plots and unfertilized control plots were observed only at one of the four sites (Jork, organic fruit production) in soil respiration and in soil animal feeding activity. There were no significant differences in the soil biological parameters between plots that had received different types of organic fertilizers. There were also no significant differences between different levels of fertilizer application which were ranging from 30 to 135?kg N/ha. The soils from the four investigation sites differed significantly in their biological status. At the tree nurseries there were only few earthworms (ca. 15/m²) and a low microbial biomass (105 ... 190?mg C_mik/kg dry soil). The soils under fruit production were more intensively colonized by soil organisms, according to the lower degree of soil disturbance in these cultures. In tree nursery as well as in fruit production the soils under organic management had higher microbial biomasses and a wider ratio of C to N in the microbial biomass compared to their counterparts with integrated management. This is indicating that there is a stronger tendency to incorporate additional N into the microbial biomass in the organically managed soils. If there is a high activity of (endogeic) earthworms the nutrients are quickly remobilized and so become available for the plants.     

Streuobst – Betreiberkonzepte und Sortenempfehlung

Fruit landscaping can be a helpful addition for the conservation of old fruit varieties in gene banks. Very important for this are a long-term security of the plantations, reliable definition of the varieties and documentation with scientific attention. Four management conceptions with a different intensity are possible:

1. Nature conservation (natural biotope without regulations),
2. Landscaping (without state promotion impossible),
3. Fruit utilization for processing (needs sufficient cultivation and special marketing conceptions) and
4. Clearing and new plantation of over aged trees.

Recommendation of varieties for new plantations with old cultivars for conservation and special using in landscaping needs the consideration of regional features and scientific results especially of resistance characteristics of the varieties.     

Einfluss von Biostimulanzien und Lichtreflexionsfolie auf die Fruchtqualität und Farbentwicklung bei Apfel

The aim of this research was to improve inner and external fruit quality and fruit colouration using four-year-old apple ‘Braeburn, Hillwell’ trees on M9 (3?m × 1?m spacing) by employing reflective ground covers and biostimulants at Klein-Altendorf, nr. Bonn, Germany (50°N). Two reflective ground covers were spread on both sides of tree rows seven weeks before anticipated harvest and two biostimulants were applied two times – four and two weeks before harvest. Adjacent trees of the same row without reflective ground cover or without biostimulants served as control.Reflective ground covers significantly improved red colouration from 71°hue in the control to 49°hue with the ground cover Lumilys® and to 40°hue with Extenday®. The red colouration of the lower surface of fruits improved from 85°hue in the control to 52°hue with Lumilys® and 40°hue by Extenday®. Apple trees with Extenday® and Lumilys® produced 69% and 44% well-coloured fruit (with 75–100% fruit colouration) compared with 16–26% in the control.By contrast, an acceleration of ripening processes was not observed in plots with reflective ground covers compared with the control. There were no differences in sugar contents (°Brix) and fruit firmness (kg/cm²), but starch breakdown in fruit with reflective mulch was significantly delayed compared with the control resulting in retarded maturation.An economic analysis based on material costs and lifespan – excluding the labour costs for spreading and removing the ground covers – showed an economic advantage, if these mulches are used more than once a year.Both biostimulants showed neither effects on inner and external fruit quality nor on fruit colouration. Fruits with Wuxal®ATRiun or Sunred® did not improve the percentage of well-coloured fruits (75%–100% fruit surface with red colouration) compared with the untreated control. Similarly, inner and external fruit quality showed no significant differences in fruit firmness, sugar content and starch degradation. An economic analysis based on chemicals’ costs – excluding the labour costs for applying the biostimulants – resulted in no economic advantage. The chlorophyll – based ‘Index of Absorption Difference’ (IAD; measured non-destructively by the DA-meter) in some cases correlated positively with the Streif (maturation) index based on destructive assessment fruit firmness, sugar content and starch breakdown in an ‘ART system’.     

Abteilung Fruchtqualit?t und Obstlagerung

Throughout its existence, the Fruit Quality and Storage Section has been subject to continuous change. Research foci have addressed relevant problems in fruit production. Until the early post-war period, questions of adaptive fertilisation were prominent. Following the 1962 storm tide, the conversion from seedling to slow-growing rootstocks as well as polder creation influenced research of the Section. Increasing demands by food retailers for enhancement and maintenance of fruit quality have gained an ever larger importance during the past 30 yrs. In particular, the inclusion of experimental fruit storage since 1990 has led to a major shift in the focus of research.     

Einsatz von Kennzahlen und Beratungsbriefen als Controlling-Instrument für Beratung und Gartenbaupraxis an der Niederelbe

The first business management analyses of fruit farms from the Altes Land (Lower Elbe Valley, Northern Germany) date back to the financial year 1956/57 and were published in 1958 by Prof. A. Löhden in the journal Mitteilungen des Obstbauversuchsringes des Alten Landes e.V. The data compiled by Löhden from the Agrarian Report were used by the Chamber of Agriculture of Hannover to evaluate the book-keeping of those fruit farms which it supported with business development grants. In the early 1980s the fruit advisory services had to implement a comparison of the book-keeping data of fruit farms. This business management advice has been expanded subsequently. At present, some 120 fruit farmers participate at the annual comparison of the Fruit Advisory Service and the Centre of Business Management in Horticulture. The use of this controlling instrument for evaluating key business data will be demonstrated in the current article on the basis of two examples.     

GiSelAs, PIKUs und neue Giessener Klone: Ergebnisse aus europäischen und nordamerikanischen Kirschenunterlagenversuchen

Published results on vigour and productivity from European and American trials are compared for 8 size-controlling rootstocks for sweet cherries. Taking the different conditions into account, the clones can be ordered according to their size-control: most dwarfing is GiSelA 3, followed by GiSelA 5. GiSelA 12 grows a bit stronger. Next are GiSelA 6 and 148/13. PIKU 1 and 318/17 show stronger, and PIKU 3 the most vigorous growth. On GiSelA 3, GiSelA 5, GiSelA 6 and 318/17 high yields can be achieved. PIKU 1 stands out by high yields under weak conditions. Yielding potential of PIKU 3 proves to be low. Productivity on GiSelA 12 and 148/13 cannot be assessed due to the small number of data. The problems of this evaluation and the results for each of the 8 clones are discussed.     

Holzhäcksel- und Miscanthusmulch erhalten die Bodenfeuchte und fördern die biologische Bodenaktivität sowie vegetatives und generatives Wachstum junger Apfelbäume

Tree rows of a two-year-old apple (cv. ‘Topaz’) orchard in Klein-Altendorf near Bonn, Germany, were mulched with either a) shredded broadleaf tree trunks (5?cm; 29?t dm/ha) in January 2005, b) high (6?cm; 17?t?dm/ha), or c) low (3?cm, 7?t dm/ha) shredded stems of Miscanthus in July 2004 to conserve resources and achieve closed systems; uncovered soil served as control. The following results were obtained in this MSc thesis during the 2005 growing season:

1. Soil covered with any of the three mulches mineralised 7–14?kg less nitrogen per hectare throughout the growing season resulting in a more balanced nitrogen mineralisation. The reduction in nitrogen supply prevented late vegetative growth and contributed to good fruit colouration.
2. The largest soil respiration was recorded with wooden chips as mulch with a peak of 1.6?CO₂?m^–2?h^{– 1} in June/July, followed by Miscanthus mulch and the uncovered control, which indicates enhanced microbial activity in the summer as a result of medium C/N ratio, warming and better aeration of the wood chips.
3. The organic mulches preserved soil moisture with values of less than 53 centibars and with less fluctuation than in the control.
4. The organic mulches reflected ca. 10% of incident PAR 1?m above ground, i.e. more light than uncovered soil, all without affecting fruit colouration.
5. The two thicker (5?cm and 6?cm) organic mulches suppressed weed population by 63–67% relative to the control.
6. The two thicker (5–6?cm) organic mulches improved potassium uptake by the apple leaves with 1.5 % K relative to 1.3 % K in the control on a leaf dry matter basis, but reduced their calcium and magnesium content.
7. Wood chips as mulch improved vegetative growth of the apple trees during the growing season, measured as trunk diameter, of 4?mm, followed by 3.6?mm of the high Miscanthus and 2.8?mm in both the low Miscanthus mulch and the control.
8. The organic mulches enlarged apple fruit diameter from 78?mm in the control to 80?mm with a concomitant increase in fruit weight from 180?g in the control to 185–188?g.

     

Mechanische Fruchtbehangsregulierung verringerte den Junifruchtfall und verbesserte die Fruchtqualität und Fruchtgröße bei ‚Conference‘- und ‚Alexander Lucas‘-Birnen

In the absence of any chemicals approved for thinning pears but market demand for large particularly cv. ‘Conference’ fruit, the objective of the present study as part of a MSC thesis was to improve fruit quality i.e. achieve these fruit sizes by mechanical blossom thinning. Therefore, 18-year-old cv. ‘Conference’ pear trees, trained as super spindles, on quince A rootstock with a spacing of 4?×?0.4 m were used in Klein-Altendorf near Bonn, Germany; cv. ‘A. Lucas’ and un-thinned trees served as control. These pear trees with intense flowering were blossom-thinned on 15 April 2009 with rotor speeds of either 300 rpm or 400 rpm both at 5 km/h tractor speed with the new mechanical thinning device developed at the University of Bonn in 2004–2006. Therein, a vertical mast supports three horizontal rotors, whose vertically rotating tines remove excessive flowers; the device is mounted on the front three point hitch of the tractor. In 2009, a year with severe June drop, mechanical thinning reduced the intensity of the natural June drop with increasing rotor speed and was stronger reduced in cv. ‘A. Lucas’ (by ?38%) than in cv. ‘Conference’ (by ?27% relative to the control). In cv. ‘A. Lucas’, the natural June drop was as strong as mechanical thinning and resulted in large-sized 80 mm pear fruit in the control; mechanical thinning with 400 rpm further increased fruit mass by 16 g relative to the un-thinned control or 6 g larger than in the thinning with 300 rpm. In cv. ‘Conference’, fruit fell within the next larger fruit size class after the stronger mechanical thinning with 400 rpm at 5 km/h: the portion of pear fruit in the 75/80 mm size class was 2 fold and in the 80/85 mm size class was 6 fold that in the control. The portion of <?60, 60/65 mm and 65/70 mm fruit was halved relative to the control; the average fruit mass was increased by 40 g. Vegetative growth appeared unaffected by mechanical thinning. The risk of both over-sized fruit and over-thinning appears small, since mechanical thinning reduced the natural June drop and did not induce subsequent fruit drop. Mechanical thinning was more efficient in cv. ‘Conference’, as intended, despite more intense flowering in cv. ‘A Lucas’. An economic evaluation proved difficult, since the natural June drop particularly in cv. ‘A. Lucas’ led to large-sized fruit (80 mm) in the control, and any (mechanical) thinning is associated with lower yields (?26% in cv. ‘Conference’ and ?12% in cv. ‘A. Lucas’). Overall, the results indicate the potential of mechanical thinning as a substitute (or combination partner for chemical thinning if approved) in pear.     

Bewertung des Anbau- und dekorativen Wertes deutscher und mongolischer Sanddornherkünfte (Hippophae rhamnoides L.)

Zusammenfassung Sanddorn erfreut sich aufgrund seiner wertvollen Inhaltsstoffe und deren vielseitiger Nutzbarkeit als neue Obstart wachsender Beliebtheit. Aus der Züchtung in Berlin-Baumschulenweg gingen bisher 5 weibliche und 4 männliche Sorten unterschiedlicher Reifezeit hervor. Weitere Selektionen aus verschiedenen Kreuzungen europäischer und mongolischer Herkünfte stehen noch in Prüfung. Sie wurden bezüglich ihrer agronomischen und ihrer Fruchtmerkmale bewertet. Die Variabilität einzelner Merkmale war z. T. extrem hoch (z. B. Vitamin-C-Gehalt zwischen 17 und 340 mg/100 g, Karotin zwischen 6,5 und 23,8 mg/100 g). Das zeigt, dass weitere züchterische Verbesserungen möglich sind. Alle Sorten und zahlreiche Klone sind im Institut für Obstzüchtung in Dresden-Pillnitz erhalten und stehen für weitere Untersuchungen zur Verfügung. Um sicher zu gehen, später auftretende Probleme züchterischer wie phytopathologischer Art lösen zu können, muss möglichst die gesamte vorhandene genetische Vielfalt einer Art für zukünftige Arbeiten erhalten werden. Dafür sind staatlich geförderte Genbanken notwendig.     

Mikroklima-, Farb- und Geschmacksverbesserung durch Licht reflektierende Folie zu verschiedenen Auslegeterminen bei ��Elstar��- und ��Jonagold�� ?pfeln unter schwarzem und wei?em Hagelnetz

Fruit colouration of the bi-coloured apple cvs ??Elstar Elshof?? and ??Jonagold Wilmuta?? on M9 under hailnet is often hampered due to light deprivation in the autumn, caused by shorter photoperiod, declining solar angle and decreasing light intensity. Therefore, reflective ground cover (Extenday^®) was spread early (beginning of July) or late (beginning of August) either side of the tree rows under white (88?C92% light transmission) or black (80?C84% light transmission) hailnet at the University of Bonn, Campus Klein-Altendorf (50.4°N), Germany, to improve fruit quality, particularly fruit colouration and taste, particularly sugar content. The five-year-old apple trees on M9 rootstock, spaced at 3.5 m?×?1 m, were planted in N-S orientation to optimise light utilisation; adjacent uncovered trees without reflective ground cover without hailnet served as control. The ground covers improved light reflection perpendicular from the ground in the middle of the alleyways by 14% at 90° angle, but by 5-fold at a 45° angle into the periphery of the tree canopy, both measured 1 m above ground. The diurnal course of light reflection 1 m from the ground differed distinctly from that of incident radiation: The latter depended on the East or West side of the tree row. By contrast, light reflection values depended solely on the use of reflective ground cover irrespective of hailnet and row orientation. Relative humidity and air temperature appeared unaffected by the use of reflective mulch; sunburn did not appear in any of the treatments. 1,200 colour measurements showed that the reflective ground covers improved red colouration of the downward-facing, lower and tree-facing, inner side of apple fruit of both varieties from 91?C99°hue colour angle (green) in the uncovered control to 51?C59°hue (red) irrespective of the date of spreading the mulch i.e. early or late. By contrast, no differences were observed in the sun-exposed, outer side of the fruit. The lowest fruit firmness and lowest sugar content were observed in apple fruit under the black hail-net. The firmest fruit with the largest sugar concentration (as a measure of taste) were observed in all trials with reflective mulch, particularly in the lower third of the tree canopy, starting from the uncovered control, the white hailnet to the black hailnet; sugar concentration improved with the time of mulching. Overall, the shorter time of mulching of 4 versus 8 weeks prior to anticipated harvest from the beginning of July (for cv. ??Elstar??) and mid-August (for cv. ??Jonagold??) proved sufficient for improving fruit quality, colouration and taste under both white and black hailnet at 50°N. Based on an expected 10-year lifespan with reduced UV-exposure under hailnet in North-western Europe, this currently most expensive reflective ground cover increased gross returns by 560?C840 ?/ha/year due to more well-coloured class 1 apples and a smaller percentage of poorly coloured apples (?<?25% blush) compared with the material cost of 700 or 350 ?/ha/year, if used once or twice a year, but without any labour cost involved. Financial returns varied between 210 and 490 ?/ha/year, based on double use per season of the light reflecting material, whereas single use only reached the break-even point. Hailnets are expected to increase due to climate change associated with better light conditions for reflection in the autumn and taller tree training leading to more shade in the lower tree canopy; new alternative reflective, low cost ground covers may then contribute to better utilisation of light otherwise lost in the alleyways and better economy for use in a fruit orchard.     

Profilierungstechniken in der Ernährungs- und Lebensmittelforschung

High throughput profiling techniques are applied increasingly in nutritional sciences as tools for the identification of metabolic phenotypes in response to food as well as for identification of the modes of action of individual constituents of the diet.     

Vergleich von Anbausystemen beim Apfel in Abhängigkeit von Sorte und Unterlage: Schlanke Spindel und Güttinger-V-System

To the 11th leaf the influence of two planting systems on yield and fruit size of apple cultivars ‘Golden Delicious, Weinsberg’ and ‘Jonagold, Rubinstar’ grafted on the dwarfed rootstocks M 9 and P 16 was investigated. The planting systems “Slender Spindle” (3.25 × 1.25 m) and “Güttinger-V-System” (3.50 × 0.60 m) were compared. In average of both cultivars and rootstocks the “Güttinger-V-System” let to significantly higher yields than the planting system “Slender Spindle”. The difference between the planting systems amounted to 121.7 t/ha from the 3rd to the 11th leaf. In this period the annual per-hectare yield of the “Güttinger-V-System” was in average 13.5 t higher than the yield of the “Slender Spindle”. The simple fruit weight of the 3rd to the 11th leaf was affected by the planting system. For both rootstocks and cultivars the simple fruit weight of the “Slender Spindle” was significantly higher than that of the “Güttinger-V-System”. However the fruit size sorting showed for both cultivars no mentioning differences between the planting systems. To the additional yield of the “Güttinger-V-System” face additional costs for the installation of the orchard and for the formation of crown. Thus the decision for this planting system will be influenced in a high measure from the producer price.     

Vergleich von Anbausystemen bei der Birne in Abhängigkeit von Sorte und Unterlage: Schlanke Spindel und Güttinger-V-System

To the tenth leaf the influence of two planting systems on yield and fruit size of pear cultivars ‘Conference, 202’ and ‘Alexander Lucas’ grafted on the rootstocks Quince A (MA) and Quince C (MC) was investigated. The planting systems “Slender Spindle” (3.25?×?1.25 m) and “Güttinger-V-System” (3.50?×?0.60 m) were compared. The “Güttinger-V-System” led to higher yields than the planting system “Slender Spindle”. In average of both cultivars and rootstocks the difference between the planting systems amounted to 75.9 t/ha from the third to the tenth leaf. To the additional yield of the “Güttinger-V-System” face additional costs for the installation of the orchard and for the formation of crown. Thus the decision for this planting system will be influenced in a high measure from the producer price.     

Apfeltriebsucht – Stand des Wissens aus Theorie und Praxis

Phytoplasmas give rise to big economic losses in all plant growing branches worldwide. Well known in Europe is the apple proliferation disease. In order to control this disorder, the use of certificated planting material is recommended and other methods, such as vector-management and eradication of infected plants are necessary. The use of resistant cultivars or rootstocks may also be considered.     

Obstkonsum in China �C Anbau, Angebot und Preise

As a Northern hemisphere fruit producer, China??s harvest time overlaps with that in Europe and the US and has been dominating the worldwide fruit market. Prices and sources of fruit in China were examined in supermarkets in Beijing in May 2011 and combined with the official Chinese Agricultural Yearbook to analyse China??s fruit industry:

1. China has become the world??s no 1 for apple (25?C30 mil. t), pear (13.5 mil. t) and Citrus (23 mil. t) production based on the Chinese statistical agricultural yearbook (2009), and no. 3 for strawberry (0.65?C0.8 mil. t), with an overall fruit production of 105?C113 mil. t/year and a tendency to increase domestic fruit production and consumption.
2. Fruit acreages, reported in 2009, were 2 mil. ha for apple, 1 mil. ha for pear (inclu-ding Nashi) and 2 mil. ha for Citrus and 0.083 mil. ha for strawberry totalling 10.7 mil. ha for fruit production in China, with a tendency towards slightly decreasing orchard acreage. The average farm size was ?£?0.5 ha.
3. Fruit consumption in China was calculated as 18?C21 kg apple/head/year, 10.1 kg pear/head/year (incl. Nashi) and 77?C81 kg fruit/head/year based on 1.33 billion inhabitants and production data; this is a rise in domestic fruit consumption from 45 kg in 2002/2003 to 77?C83 kg fruit/head/year in 2008/2009.
4. Jujube fruit yielded a farm gate price of 1.20 ?/kg and cv. ??Fuji?? apple 0.55 ?/kg (5 Yuan) as for most pome and stone fruit (with higher prices in the farm shop), which doubled to 1.10 ?/kg after sea export from Qingdao harbour to Rotterdam.
5. Prices for Chinese cv. ??Fuji?? apples in Beijing supermarkets ranged from ? 0.84/kg for a poor class II to ? 2.80/kg for class I fruit. Three (??Red Delicious??, ??Gala?? and ??Granny Smith??) out of five apple varieties on sale out-of-season in China??s Capital were imported from the US or Chile, with higher prices ranging from ? 3.25 for imported cv. ??Gala??, 4.15 ?/kg for ??Red Delicious?? to ? 4.90 for cv. ??Granny Smith??.
6. The Chinese viz Asian taste prefers large, juicy and sweet, red or yellow fruit with little acidity and smooth skin viz peel finish. Surprisingly, ??Granny Smith?? apples were sold as ??green apples?? without variety name at the highest price of all apple varieties.

     

Moderne Apfelz��chtung: Genetische Verarmung und Tendenzen zur Inzucht

The apple varieties used in the modern commercial apple cultivation are nearly all genetically based on six relatively disease susceptible ??ancestorvarieties??: Golden Delicious, Cox Orange, Jonathan, McIntosh, Red Delicious and James Grieve. This applies to varieties bred after 1920 until today, including the new scab resistant varieties. The following article shows the dimension of the genetical narrowing and problems concerning the vitality of modern apple varieties. The author has compared the healthiness of old and new apple varieties in his trialorchard under no fungicide-spray conditions. As a conclusion out of his observations he calls to bethink an overall??not just reduced on scab resistance??term of vitality, as well as to use also the genetical potential of old apple varieties.     

Sind Obstanlagen geeignete Nahrungs- und Nisthabitate für Wildbienen?

Zusammenfassung Wildbienen sind inzwischen eine allgemein anerkannte Option für die Bestäubung im Obstbau. Ihre Funktion als Bestäuber wird vor allem dann erheblich an Bedeutung gewinnen, wenn die Zahl der Imker und der Honigbienenvölker weiter zurückgeht. Wir untersuchten die Bedeutung von Obstanlagen als Nahrungs- und Nisthabitate für Wildbienen in der Obstversuchsanlage Klein-Altendorf bei Bonn. In dieser Obstversuchsanlage und in ihrer unmittelbaren Umgebung wurden während der Vegetationsperiode 2002 und 2003 insgesamt 59 Wildbienenarten nachgewiesen. Während der Obstblüte wurden 25 Bienenarten erfasst, davon 21 in der Obstanlage. Eine Biotoptypenkartierung ergab, dass weder die Obstversuchsanlage noch ihre Umgebung im Umkreis von einem Kilometer ausreichend Nistmöglichkeiten für Wildbienen boten und somit eine spontane Besiedlung nahezu ausgeschlossen war. Während der Obstblüte waren erheblichen Ressourcen an Pollen und Nektar vorhanden. Kirschblüten enthielten im Mittel der untersuchten Sorten Sam, Oktavia, Schneiders, Regina und Kordia pro Blüte 12,5 µl Nektar, wobei Blüten der Sorte Sam mit 16 µl am meisten Nektar enthielten. Die Anzahl Pollenkörner pro Blüte lag im Durchschnitt der Kirschsorten bei 74.000, wobei die Sorte Sam mit 99.000 die meisten Pollen hatte. Apfelblüten produzierten im Mittel der Sorten Gala, Elstar, Golden Delicious und Jonagold 8,5 µl Nektar, wobei die Sorte Jonagold mit 17 µl den meisten Nektar enthielt. Die durchschnittliche Pollenproduktion einer Apfelblüte lag bei 46.000; die meisten Pollen (72.000) enthielten Blüten der Sorte Gala. Eine Modellrechnung zeigt, dass in dieser Obstanlage mit dem Angebot an Kirschpollen/ha 350.000 Individuen der zur Kirschblüte fliegenden Osmia cornuta aufgezogen werden könnten und mit den Apfelpollen/ha 22.200 Individuen der später auftretenden Mauerbiene Osmia rufa. In den untersuchten Blüten der Süßkirschen waren bei einer Sorte bis zu 62% der Pollen taub. Da sie von den Bestäubern dennoch auf die Narben übertragen werden, kann dies zu einer Fehlbelegung oder zur Verstopfung der Narbenoberfläche führen. Zudem ist zu erwarten, dass tauber Pollen im Larvenfutter der Wildbienen zu Entwicklungsstörungen oder zum Tod der Larve führt. Die Qualität der Nektar- und Pollenressourcen hängt vom Anbausystem, der Obstart und Sorte ab. Vorgeschlagen werden Maßnahmen zur Gestaltung und Optimierung von Obstanlagen und ihrer Umgebung, mit dem Ziel, Wildbienen nachhaltig anzusiedeln und als Bestäuber zu nutzen. Ausschlaggebend hierfür sind Nistplätze für oberirdisch und im Boden nistende Arten und Nahrungsressourcen, die den Wildbienen auch noch nach der Obstblüte zur Verfügung stehen. So kann erreicht werden, dass Wildbienen ihren Lebenszyklus vollenden können und im nächsten Frühjahr eine neue Generation für die Bestäubung zur Verfügung steht.     

Sind Obstanlagen geeignete Nahrungs- und Nisthabitate für Wildbienen?

Wildbienen sind inzwischen eine allgemein anerkannte Option für die Bestäubung im Obstbau. Ihre Funktion als Bestäuber wird vor allem dann erheblich an Bedeutung gewinnen, wenn die Zahl der Imker und der Honigbienenvölker weiter zurückgeht. Wir untersuchten die Bedeutung von Obstanlagen als Nahrungs- und Nisthabitate für Wildbienen in der Obstversuchsanlage Klein-Altendorf bei Bonn. In dieser Obstversuchsanlage und in ihrer unmittelbaren Umgebung wurden während der Vegetationsperiode 2002 und 2003 insgesamt 59 Wildbienenarten nachgewiesen. Während der Obstblüte wurden 25 Bienenarten erfasst, davon 21 in der Obstanlage. Eine Biotoptypenkartierung ergab, dass weder die Obstversuchsanlage noch ihre Umgebung im Umkreis von einem Kilometer ausreichend Nistmöglichkeiten für Wildbienen boten und somit eine spontane Besiedlung nahezu ausgeschlossen war. Während der Obstblüte waren erheblichen Ressourcen an Pollen und Nektar vorhanden. Kirschblüten enthielten im Mittel der untersuchten Sorten Sam, Oktavia, Schneiders, Regina und Kordia pro Blüte 12,5 µl Nektar, wobei Blüten der Sorte Sam mit 16 µl am meisten Nektar enthielten. Die Anzahl Pollenkörner pro Blüte lag im Durchschnitt der Kirschsorten bei 74.000, wobei die Sorte Sam mit 99.000 die meisten Pollen hatte. Apfelblüten produzierten im Mittel der Sorten Gala, Elstar, Golden Delicious und Jonagold 8,5 µl Nektar, wobei die Sorte Jonagold mit 17 µl den meisten Nektar enthielt. Die durchschnittliche Pollenproduktion einer Apfelblüte lag bei 46.000; die meisten Pollen (72.000) enthielten Blüten der Sorte Gala. Eine Modellrechnung zeigt, dass in dieser Obstanlage mit dem Angebot an Kirschpollen/ha 350.000 Individuen der zur Kirschblüte fliegenden Osmia cornuta aufgezogen werden könnten und mit den Apfelpollen/ha 22.200 Individuen der später auftretenden Mauerbiene Osmia rufa. In den untersuchten Blüten der Süßkirschen waren bei einer Sorte bis zu 62% der Pollen taub. Da sie von den Bestäubern dennoch auf die Narben übertragen werden, kann dies zu einer Fehlbelegung oder zur Verstopfung der Narbenoberfläche führen. Zudem ist zu erwarten, dass tauber Pollen im Larvenfutter der Wildbienen zu Entwicklungsstörungen oder zum Tod der Larve führt. Die Qualität der Nektar- und Pollenressourcen hängt vom Anbausystem, der Obstart und Sorte ab. Vorgeschlagen werden Maßnahmen zur Gestaltung und Optimierung von Obstanlagen und ihrer Umgebung, mit dem Ziel, Wildbienen nachhaltig anzusiedeln und als Bestäuber zu nutzen. Ausschlaggebend hierfür sind Nistplätze für oberirdisch und im Boden nistende Arten und Nahrungsressourcen, die den Wildbienen auch noch nach der Obstblüte zur Verfügung stehen. So kann erreicht werden, dass Wildbienen ihren Lebenszyklus vollenden können und im nächsten Frühjahr eine neue Generation für die Bestäubung zur Verfügung steht.     

Pflanzenschutz im Wandel – Zwischen Europ?ischer Gesetzgebung und innovativer Forschung

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Pflanzenschutz im Wandel – Zwischen Europ?ischer Gesetzgebung und innovativer Forschung