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.     

Sorten-Unterlagen-Kombinationen f��r den Mostapfelanbau

In a field trial 5 rootstocks (seedling, M 25, A 2, MM 106, MM 111) and 13 varieties were investigated under Northeast German climate conditions to obtain information on the optimal rootstock-variety combinations for intensive juice apple production. Further the sugar and acid content of the fruits were determined. Due to the fact that exclusively scab resistant varieties were examined, the occurrence and stability of the resistance were of special interest. The most favourable rootstocks were M 25 (highest absolute yield) and MM 106 (highest specific yield). The varieties ??Judeline??, ??Rebella??, ??Resi??, ??Angold??, ??Schwechow 3?? and ??Priam?? had the highest absolute yield (mean of all rootstocks). The suitability of these six varieties for juice apple production was described. Although fungicides were used for controlling apple scab, particularly varieties with the Vf resistance factor were infected. A strong scab resistance had the variety ??Reka?? (Vr).     

Molekulare Diagnostik in der Lebensmittel��berwachung

Molecular diagnostic is frequently a confirmed part in the food microbiological survey of the official food safety control. So the diagnostic tools are used for a fast screening for presence or absence of pathogens or to differentiate the isolates.     

Ahornschmierlaus Phenaccocus aceris als ��bertr?ger des Little Cherry Virus-2 an S��?kirsche in Baden-W��rttemberg nachgewiesen

The Apple mealybug Phenacoccus aceris was verified as the vector of the Little Cherry Virus-2 (LChV-2) in Baden-Württemberg. However, this does not exclude the participation of even more different vectors. Because the Apple mealybug is more spread than presumed as of yet, this vector should be specifically controlled as well as fought in cherry orchards. If planting new cherry orchards it must be strictly adhered to virus-free, certificated plant matter, so that in areas free from Little cherry an epidemic as in the ??Altes Land?? can be avoided.     

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.     

Mehr Chilling f��r Obstb?ume in w?rmeren Wintern?

The objective of this study was the calculation of winter chill for fruit trees in the Meckenheim fruit growing region for all winters since 1958 and the evaluation of long-term trends in response to global warming. A further objective was the comparison of three winter chill models, the Chilling Hours Model (Chilling Hours??CH), the Utah Model (Chill Units??CU) and the Dynamic Model (Chill Portions??CP) with respect to temporal trends and seasonal variation in chilling intensity. To meet these objectives, about 120,000 hourly temperature measurements from Klein-Altendorf were correlated with daily temperature extremes. From this relationship, a long-term record of 466,000 hourly temperature data was constructed and used to calculate winter chill between 1st October of each year and three dates of the following year for all winters since 1958/1959. On average over all years, 955 CH, 1160 CU and 58.0 CP had accumulated in the Meckenheim fruit growing region by 1st January, 1356 CH, 1527 CU and 77.3 CP by 1st February, and 1727 CH, 1883 CU and 96.1 CP by 1st March. Coefficients of variation varied between 14 and 16% for the Chilling Hours Model, between 18 and 19% for the Utah Model and between 9 and 10% for the Dynamic Model. In spite of significant warming of the site, no clear long-term trends were detected. Due to the structure of the winter chill models, which do not consider freezing temperatures as chilling-effective, the highest chilling was not registered in the coldest winters, but rather when average temperatures between early December and late February were between 2 and 6°C. The coldest winter on record (1963/1964; mean winter temperature of ??4°C) had by far the lowest winter chill total, and chilling during the more recent cold winters 2009/2010 and 2010/2011 was also below average. Only very pronounced warming reduced winter chill, with the warmest winter on record (2006/2007; mean winter temperature of 7.1°C) accumulating less winter chill than slightly cooler winters. As long as such extreme temperatures remain exceptional, fulfilment of chilling requirements of local apple and cherry cultivars should not become critical. It is important to note, however, that substantial knowledge gaps exist in the field of fruit tree dormancy, which will have to be closed, before more reliable projections of future fulfilment of chilling requirements can be made.     

Antagonisten und Pr?datoren der Maulbeerschildlaus Pseudaulacaspis pentagona (Targioni-Tozzetti, 1886) (Homoptera: Diaspididae) in Baden-W��rttemberg

Antagonists of the white scale (Pseudaulacaspis pentagona, Targioni-Tozzetti, 1886) were determined from peaches and sweet cherries as host plant at the orchards of the Centre for Agriculture and Technology Augustenberg (LTZ) in 2009 and 2010 as well as from four other commercial red and black currant orchards in Baden-Wuerttemberg in 2010. The study focused mainly on the parasitoid species of P. pentagona as well as the rate of parasitism of white scale caused by these parasitoids using emergence traps with invested branch samples of the different host plants in the laboratory. Beside the parasitoids, possible predators of the white scale were observed in the field in 2010 at the orchard of the LTZ. The two parasitic wasp species Aphytis diaspidis and Encarsia berlesei (Howard, 1881 and 1906) were determined as parasitoids of the white scale, whereas A. diaspidis was dominant at most sites. Rate of parasitism caused by both species ranged from 1.9 to 23.0%. The Kidney-Spot Ladybird Beetle (Chilocorus renipustulatus, Scriba, 1790) could be observed as a predator of the white scale in the field.     

Auswirkungen von Ausd��nnungsma?nahmen auf Ertragsparameter, Krankheitsbefall und Fruchtqualit?t von S��?kirschen (Prunus avium L.) unter ?kologischen Anbaubedingungen

In 2010, various thinning methods were tested in an organically managed cherry orchard at the experimental farm of the Institute in Vienna. We tested a portable thinning machine (Effleureuse) and a manual method to remove flowers, and thinning of young cherries at the stage of pea size. Between beginning of flowering and full flowering we treated twice with wettable sulphur (4 %), lime sulphur (3 %), vinasse (6 %), potassium soap (Neudosan 6 %) and copper (Cuprofor 0.5 %) as well as ATS (1.8 %) as IP-standard. Additionally to the thinning effect, the impact on fruit size, fruit quality and diseases (Monilinia ssp.) was assessed. Some treatments (Effleureuse, manual thinning of young fruits, lime sulphur, ATS) showed a strong thinning effect and an increase of fruit size. Nevertheless, yield losses due to lower number of fruits caused by thinning could only partly be replaced through higher fruit size. The Effleureuse showed a high thinning effect, because of lower costs it is more suitable for farmers than hand thinning of flowers or fruits. The treatments with lime sulphur and wettable sulphur had a reducing effect on flower infestations with Monilinia laxa. No influence on fruit diseases and internal fruit quality could be found between treatments and control.