Mekjell Meland

Seniorforsker

(+47) 906 28 538
mekjell.meland@nibio.no

Sted
Ullensvang

Besøksadresse
NIBIO Ullensvang, 5781 Lofthus

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The objective of this study was to determine and compare the sugar profile, distribution in fruits and leaves and sink-source relationship in three strawberry (‘Favette’, ‘Alba’ and ‘Clery’) and three blueberry cultivars (‘Bluecrop’, ‘Duke’ and ‘Nui’) grown in organic (OP) and integrated production systems (IP). Sugar analysis was done using high-performance anion-exchange chromatography (HPAEC) with pulsed amperometric detection (PAD). The results showed that monosaccharide glucose and fructose and disaccharide sucrose were the most important sugars in strawberry, while monosaccharide glucose, fructose, and galactose were the most important in blueberry. Source-sink relationship was different in strawberry compared to blueberry, having a much higher quantity of sugars in its fruits in relation to leaves. According to principal component analysis (PCA), galactose, arabinose, and melibiose were the most important sugars in separating the fruits of strawberries from blueberries, while panose, ribose, stachyose, galactose, maltose, rhamnose, and raffinose were the most important sugar component in leaves recognition. Galactitol, melibiose, and gentiobiose were the key sugars that split out strawberry fruits and leaves, while galactose, maltotriose, raffinose, fructose, and glucose divided blueberry fruits and leaves in two groups. PCA was difficult to distinguish between OP and IP, because the stress-specific responses of the studied plants were highly variable due to the different sensitivity levels and defense strategies of each cultivar, which directly affected the sugar distribution. Due to its high content of sugars, especially fructose, the strawberry cultivar ‘Clery’ and the blueberry cultivars ‘Bluecrop’ and ‘Nui’ could be singled out in this study as being the most suitable cultivars for OP.

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The presence of pollinators in orchards is crucial to obtain high fruit set and yields of fruits. Despite the fact that sour cherry cultivars are mainly autogamous, insect visits are still of great importance for their propagation. In order to attract and reward pollinators, flowers have to provide adequate nourishment to them. Besides nectar, bees gather pollen, which are a prerequisite for normal colony growth and development of their broods. ‘Oblačinska’ sour cherry (Prunus cerasus L.), an autochthonous cultivar, is the most highly planted cultivar in Serbian commercial orchards. Since the cultivar is actually a mixture of different clones, variability in numerous traits and, particularly, its yields has been reported. Since phenolic compounds are considered to be fundamental pollen chemicals, the aim of this study was to determine the phenolic compounds profile in pollen collected from 15 ‘Oblačinska’ sour cherry clones with varying productivity levels. Solid phase extraction (SPE), combined with ultra-high-performance liquid chromatography coupled with a diode array detector and a triple quadruple mass spectrometer (UHPLC DAD-MS/MS), was used to analyse the polyphenolic profile of pollen. Among 23 components quantified, rutin was the most abundant phenolic compound. It ranged from 98.49 (clone V/P) to 358.83 mg kg-1 (clone III/9) and was observed to contribute, on average, 56% of the total phenolic compounds in pollen as quantified in different ‘Oblačinska’ sour cherry clones. In addition to this compound, clones contained significant amounts of chlorogenic acid (12.92%), astragalin (8.19%), and hyperoside (5.59%) as well. Cluster analysis grouped pollen clones in four different clusters, which showed that clones III/9, IV/8, and V/P had unique phenolic profiles. Despite the significant differences among the studied clones, the contents of chlorogenic acid, rutin, naringin, hyperoside, astralgin, and phlorizin were distinguishable between the clusters.

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Sweet cherry production worldwide is grown in the open land. Production technique is more or less similar with scions grafted on dwarfing and semi-dwarfing rootstock and trees arranged in single rows. Sweet cherries can be grown in Norway in areas with suitable local climatic conditions up to 60°N. All orchards have high-density planting systems and are rain covered. Rain-induced fruit cracking in cherries remains a problem at an international level. The most common systems in Norway are multibay high tunnel systems and retractable rain covers. Covered orchard tunnel systems offer not only the advantage of rain exclusion but also allow additional manipulation of the environment, tree growth and fruiting. In general, sweet cherry high tunnel production gives increased yields of larger fruit than in the open land, but investment costs are higher. One more advanced way of producing sweet cherries is to grow the trees in small pots in greenhouses. A greenhouse gives opportunity to control the temperature regime and in that way program the maturity of the fruits. Research is conducted to test different cultivars, rootstocks, training methods in high-density production systems (1 tree m-2) with different fertigation levels. Preliminary results show that the yield potential is much higher than in the open land with larger fruits. Challenges are to optimize the water and nutrition supply and adjust the temperatures to obtain large yields of high quality fruits during different periods of the season.

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Graminor Njøs har dei siste 20 åra gjennomført eit kryssingprogram i plommer (Prunus domestica L.) Føremålet har vore og er å skaffa norske fruktdyrkarar sortar som gjev stor avling med kvalitetsfrukt og som er tilpassa det norske klimaet. I denne rapporten er teke med kryssingsresultat frå sortar som er eller har vore i dyrking i Noreg dei siste åra. Rapporten presenterer også førebels data på blomstringstid og pollenspiring .Detaljert informasjon om sortane som er omtala i rapporten er presenterte på web-sida www.fruktsorter.no.

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European plums (Prunus domestica L.) blossom abundantly most years and often set too many flowers. If these excessive numbers of fruitlets remain on the trees until harvest, the crop would consist of small, unmarketable fruits of low fruit quality. Thinning agents like ammoniumthiosulphate (ATS), sulphur and soya oil desiccate flowers, especially stigma, which is the most sensitive tissue part of the flower. This way, the main effect of blossom thinning treatments is the disruption of pollination and fertilization. Thinning trials were conducted at a commercial orchard near the shore of the Hardangerfjord near Nibio Ullensvang, western Norway (60.2°N) on mature ‘Jubileum’ trees, all grafted on ‘St. Julien A’ rootstock. The trees were treated with 0.4, 0.8, 2 and 4% sulphur; a mixture of 0.4% sulphur + 2% soya oil and 1.5% ATS (liquid and powder formulations), at full bloom. All treatments were compared with hand-thinned and unthinned trees which were used as a control. Experimental trees were sprayed to the point of run-off with a hand sprayer during May 2008 and 2009 at full bloom. Flower thinners were efficient at relatively low temperatures which is a benefit in a cooler climate. In 2008 all thinning treatments reduced fruit set compared to unthinned controls for all cultivars. Sulphur and soya oil, both alone and in combination, were significantly less effective than ATS. In 2009, fruit set was higher and the effects of all thinning agents were lower. Fruit set decreased with increasing sulphur concentrations, but fruit thinning was not sufficient, even at the highest concentration. Both the liquid and powder formulations of ATS gave the same thinning effects. For all thinning treatments, both significant yield reductions and fruit weight increment were noticed during the experimental period. Fruit over color and soluble solids were generally higher and increased significantly with lower crop load, while fruit firmness (Durofel) and total acidity were less affected. In conclusion, different concentrations of sulphur had a moderate thinning effect and are not recommended for use as plum thinners under these conditions. Instead, 1.5% ATS application, (liquid and powder) applied at full bloom, resulted in adequate thinning of ’Jubileum’ plums under cool mesic northern climatic conditions.

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Due to their Mendelian inheritance, microsatellites or SSRs (simple sequence repeats) can readily be used for parentage analyses of pear seedlings, thus revealing the female and male parents of the plant. However, in cases where obtained pear seeds display low viability, conducting a parentage analyses on the pear seeds themselves could be used in order to identify the male parent (successful pollinator). In this study, batches of seeds were extracted from fruits of the triploid ‘Ingeborg’ pear (‘Conference’ × ‘Bonne Louise’), the main commercial pear cultivar in Norway. Mature pears were collected from eight commercial pear orchards located in Ullensvang, at 60° North and seeds were collected. Genomic DNA was subsequently isolated from the obtained seed batches and genotyped using 12 microsatellite markers. The same markers were also used for the genetic characterization of ‘Ingeborg’ and five pear genotypes used as pollinators in the sampled orchards (‘Clara Frijs’, ‘Herzogine Elsa’, ‘Anna’, ‘Colorée de Juillet’ and ‘Belle lucrative’). The obtained SSR profiles were used in paternity analyses, as well as for gene assignment analyses. Both approaches identified pear ‘Clara Frijs’ to be the most successful pollinator in most of the sampled orchards. Subsequent S allele genotyping of ‘Ingeborg’ and five pear genotypes used as pollinators in the sampled orchards revealed that the preferential pollination by individual genotypes was not caused by gametophytic incompatibility or semi-compatibility.

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The Norwegian newly bred pear cultivar, Celina/QTee®, which was launched in 2010, has been released from the Norwegian breeding program that was initiated in 1983. It was derived from the combination ‘Colorée de Juillet’ × ‘Williams’. In Norway the flowering is medium to late and it ripens in the beginning of September. It has large attractive fruits with a red blush. It has a good fruit quality, storability and shelf life. Cross pollination is necessary in order to have high yields of this diploid cultivar. Pollination of ‘Celina’ with pollen of four donors (‘Conference’, ‘Kristina’, ‘Anna’ and ‘Fritjof’), together with open- and self-pollination were studied in this experiment during the 2016 season in Norway. The dynamics of the pollen tube growth (third, sixth and ninth day after anthesis) in style (upper, middle and lower third) and parts of the ovary in all crossing combination, were observed by fluorescent microscopy. Besides giving the best results regarding the average number of pollen tubes in different parts of pistils and the dynamics of pollen tube growth, ‘Conference’ was the only one of which the pollen tubes didn’t show any incompatible signs while growing through the transmitting tissue of the ‘Celina’ style. According to those preliminary results, ‘Conference’ was the best pollenizer, followed by ‘Kristina’. The study has to be repeated for another season.

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Introduction and background: Autochthonous fruits in Bosnia and Herzegovina (B&H) represent great opportunities for fruit breeding, because they could be grown without costly agricultural inputs and offer valuable assets for the fruit processing industry providing a specific and different sensory taste for the fruit products. Hence, the objective of this study was to sensory evaluate fruits from 34 autochthonous apple and 29 pear cultivars in 2012 and 2013 from an ex-situ collection in B&H by eight trained panelists, using Quantitative Descriptive Analysis (QDA). Experimental: Flavour of fruits was described by the eight sensory attributes a) flavour: odour intensity, b) sweet, c) sour, d) green, fruit, e) floral flavour, f) typically, g) after taste and h) overall conception and subjected to principal component analysis (PCA) to visualise the sensory attributes. Results: For apple, the traditional cvs. ‘Prijedorska Zelenika’, ‘Paradija’, ‘Srebrenička’, ‘Bukovija’ and ‘Ljepocvijetka’ reached the best flavour scores in both years, while in pear, cvs. ‘Takiša’, ‘Hambarka’, ‘Dolokrahan’ and ‘Kačmorka’ exhibited the best flavour in both years, followed by cvs. ‘Begarika’, ‘Jeribasma’, ‘Ahmetova’ and ‘Hambarka’ with intense floral flavour and odour. In these tastings, B & H grown apple cv. ‘Golden Delicious’ also scored highly compared with cvs ‘Idared’, ‘Granny Smith’ and ‘Gala’ with a lesser characteristic apple flavour and pear cvs ‘Williams’ and ‘Sweet Harrow’ scored better than ‘Alexander Lukas’ and ‘Gellerts’ from B & H.

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Hjå eple og plomme er det heilt turvande å regulera avlinga for å oppnå jamne avlingar av god kvalitet. I kommersiell dyrking er vanleg dyrkingspraksis å regulera avlinga kjemisk eller med hand under blomstringa eller på kartstadiet. Den kjemiske tynninga vert utført under blomstringa eller på liten kart. Då vert grovtynninga utført. I etterkant vert det justert for hand. Dei siste åra har det i Europa vorte arbeidd med alternative løysingar som er mekanisk tynning med maskin. Prinsippet er eit traktormontert utstyr med roterande trådar som vert køyrt på kvar sida av trerekkja under blomstringa. Ein del blomar vert då slått av slik at ei grovtynning vert gjort. Feltsesongen 2010 vart gjennomført to feltforsøk med utprøving av den tyske maskinen Baum for mekanisk blomstertynning, eit i eple med eplesorten Summerred poda på grunnstamma M9 og eit i plomme med plommesorten Opal poda på grunnstamma St. Julien A. Feltforsøka vart gjennomførde i kommersiell frukthagar nær Nibio Ullensvang........

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Tunnel production of sweet cherry results in higher yields of larger fruit than in the open. When cherry trees were grown under tunnels in Norway, fruit cracking was higher in a year when soils were saturated and when 20 ppm gibberellic acid was applied at straw color. In this study we evaluated the effect of soil moisture on fruit cracking under tunnels. In 2013, a trial on mature 'Sweetheart'/'Colt' trees growing under high tunnels was initiated. Each plot consisted of 8 trees, spaced 2×4 m apart with 'Lapins' as guard trees. Experimental design was a split-plot design with or without 20 ppm GA3 application at straw color; and three drip irrigation regimes (zero, deficit and full based on evapotranspiration). During the season, soil water content was monitored weekly. Due to unfavorable weather conditions during bloom time, crop loads were lower than normal. Average fruit sizes were large and GA3 application at yellow straw color resulted in small increases in average fruit diameter and fruit weight with all three irrigation treatments. Fruit cracking was very variable and occurred almost exclusively at the distal side of fruit and not on the stem side. GA3-treated fruit cracked slightly more than untreated fruit. There were no differences in fruit cracking due to irrigation scheme.

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Flowering is one of the most important factors in plant fertility. Fruit set in fruits is directly influenced by the beginning, sequence, flow, duration and abundance of flowering. The objective of this study was to evaluate the variability of flowering in 41 ‘Oblačinska’ sour cherry (Prunus cerasus L.) clones, and to recommend earlyflowering genotypes for growing in warmer locations where late spring frosts are rare, and some late-flowering clones for sites more susceptible for spring frost. Results from the three years period (2004-06), showed that ‘Oblačinska’ sour cherry clones flowered in a fixed sequence each year. Average for clone VII/2N, which flowered the earliest, was April 8 and petal fall took place by April 21, whereas clone III/1 bloomed last on April 14 and petal fall took place on April 25. Statistical analysis showed that almost all sub-phases of flowering were under the significant influence of both ecological and genetic factors. Besides, ecologic factors had the highest impact to the variability of beginning of flowering (79.8%), full bloom (76.8%), petal fall (80.2%) and duration of flowering (85.56%). Clones III/1, III/13, V/6 and V/2 were considered as late flowering, whereas clones VII/2N, VI/27, VI/28 and IX/P were early flowering, taking place five days earlier then previous group.

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In order to investigate the genetic structure and differentiation among north and south European apple germplasm, 141 apple accessions maintained in ex situ collections in Norway and 110 traditional and international apple accessions from Bosnia and Herzegovina (B&H) were analyzed using 8 microsatellite markers. Bayesian analyses, based on the microsatellite data, grouped most of the accessions into two major clusters. The first cluster consisted mainly of traditional and international B&H accessions, as well as Norwegian accessions derived mostly from foreign or formal breeding programs (‘James Grieve’, ‘Katja’, ‘Summerred’, ‘Bramleys Seedling’, ‘Elstar’, ‘Katinka’, ‘Belle de Boskoop’, ‘Jacques Lebel’, etc.). The second cluster consisted almost exclusively of traditional Norwegian accessions. Further analyses divided each cluster into two sub-clusters. Cluster 1.1 included Norwegian accessions derived from foreign or commercial breeding programs, international cultivars and B&H accessions introduced from Europe and North America during the rule of Austria-Hungarian Empire. Cluster 1.2 included traditional B&H accessions introduced during the reign of Ottoman Empire. Cluster 2.1 and 2.2 consisted mainly of traditional apple accession from Norway. The results obtained indicate a clear genetic structure and differentiation among north and south European apple germplasm, presumably due to climate adaptation and selection.

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Perennial fruit crops phenology such as cherry is an ideal bio-indicator of climate change due to their long-lasting features, in particular, dates of flower opening and full bloom. This implies i) the use of several generations of cherry trees/orchards and ii) the use of the same original cherry cultivars, which existed as bearing trees and were replanted after the orchard had been grubbed. A comparison of available definitions of phenological stages in cherry previously used independently throughout Europe showed overlaps and shortcomings; hence, harmonisation was reached in this respect in the COST Cherry FA 1104 working group 2 (cherry phenology and climate change) based largely on the acceptance of the BBCH scale. This contribution presents the agreed phenology stages in both visual and wording evidence. Similarly, this contribution presents the agreed cultivars to be monitored in future for phenology and climate change effects for harmonisation. For sweet cherry, this EU-wide harmonisation includes ‘Burlat’, ‘Cristobalina’ and ‘Rita’ as early, ‘Stella’ and ‘Van’ as medium flowering and ‘Sweetheart’, ‘Regina’ and ‘Bigarreau Noire de Meched/Germersdorfer’ for late flowering cultivars for climate change effects. For sour cherry, this harmonisation resulted in ‘Meteor korai’ and ‘Anglaise Hative’ for early flowering, ‘Chrisana Pandy’ and ‘Erdibotermo’ for medium flowering and ‘Schattemorelle’, ‘Iiva, Ujfehrtoifurtos (Balaton)’ for late flowering.

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Intensive sweet cherry production in tunnel covered orchard systems offer an advantage of reducing rain-induced fruit cracking. In May 2005 four Haygrove multibay tunnel systems were installed on a gentle slope at the experimental farm at Bioforsk Ullensvang, western Norway. In these tunnels, feathered 1-year-old sweet cherry ‘Sweetheart’/Colt trees were planted with two rows at a spacing of 2×4 m in each tunnel. Each tunnel was split into two halves and covered from the end of April to beginning of September with one of two different plastic covers, having different light spectral transmittance; Luminance THB film (absorbing infrared light) and traditional Visqueen clear UV polythene film. Climatic parameters were monitored inside and outside the tunnels from the beginning of May to the beginning of September each year and yield data and fruit quality parameters were recorded. In 2009, from May 7 to September 16 the average temperature measured outside the tunnels was 14.3°C. Temperatures exceed 25°C only on two days. Temperatures inside the tunnels were 0.3°C higher on average during the entire season but exceeded 30°C on the same two hot days. Temperatures under the Luminance film were slightly lower compared to the clear film and especially reduced the temperature build up on sunny days. The harvest period was the second half of August. Average yield tree-1 was 8.8 kg (11 t ha-1) in the fourth leaf and 18.8 kg (23.5 t ha-1) fifth leaf. There were no yield differences between the two different films. Fruit size measurements found that 80% of the fruits were larger than 30 mm in diameter in the fourth leaf and 51% in the fifth leaf. Total soluble solid content was generally high (17-18%) and no significant differences were found between the different films.

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Phenological observations are considered to be sensitive tools for identifying plant responses to climatic changes. Over the last 10 years, the onset of the phenophases of sweet cherry (Prunus avium L.) during spring tended to be earlier than the previous two decades in Ullensvang, western Norway. The effects of air temperature during the winter and spring months were evaluated during two quinquennia (5-year periods), 1996-2000 (Q1) and 2003-2007 (Q2) selected due to similar mean winter and early summer temperatures, but markedly different spring temperatures. Average January-February temperatures were similar (3.3°C) in both of these two 5-year periods. However, average March and April temperatures were slightly warmer (4.0 vs. 3.2°C) and (7.3 vs. 6.9°C), respectively, in Q2 vs. Q1. These increases resulted in significantly earlier flower development. Average temperatures during the first half of May were similar for both quinquennia (10.2 vs. 10.1°C). The start of flowering (first bloom) of early maturing ‘Burlat’ and mid-season ‘Van’ were significantly different. Timing of flowering phenophases were statistically different between Q1 and Q2 for both cultivars. Mean data for ‘Burlat’ and ‘Van’ first bloom were 8 days earlier during Q2, May 2 for ‘Burlat’ and May 1 for ‘Van’. Full bloom occurred 3 days after first bloom and flowering ended 14 days after first bloom. First bloom during Q2 required 221 Baskerville-Emin Growing degree days (GDD) using a base temperature of 2°C. For the same time period in Q1, only 197 GDD were accumulated, which supports the observed temperature differences. Furthermore, we propose a flowering model for full bloom of both ‘Burlat’ and ‘Van’ in Ullensvang, which requires 254 Baskerville-Emin GDD using a base of 2°C starting on March 1.

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Vitality of pollen, in vitro pollen germination and pollen tube growth (pollen tube length and pollen tube growth rate) were investigated in Oblačinska sour cherry in order to determine the differences between clones which have divergent yielding potential. For this purpose two ‘Oblačinska’ sour cherry clones with high fruit set and high yields (II/2, III/9) and two with low fruit set and low-yielding (XI/3 and XIII/1) were used in this study. Pollen germination was done on artificial medium containing 14% sucrose and 0.3% agar-agar at room temperature (23°C). Pollen tube growth was stopped with a drop of 40% formaldehyde, 1, 3, 6, 12 and 24 h after contact with the medium. The maximum percentage of germination ranged from 13.01% (clone II/2, after 1 h) to 54.19% (clone III/9, after 24 h). Pollen tube length varied from 64.84 μm (clone XIII/1, after 1 h) to >1,100 μm (clones II/2 and III/9, after 24 h). Pollen growth rate was quite high (up to 1.71 μm min-1) after 6 h of germination, but rather decreasing until 24 h of germination (0.560.83 μm min-1). The dynamics of in vitro pollen tubes growth among the clones were quite different, especially after 12 h and 24 h of germination. Clones that are singled out as fruitful (II/2 and III/9) gave much better results regarding pollen germination and pollen tube growth in comparison to clones which were characterized by low fruit set and yields (XI/3 and XIII/1).

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Professional and scientific networks built around the production of sweet cherry (Prunus avium L.) led to the collection of phenology data for a wide range of cultivars grown in experimental sites characterized by highly contrasted climatic conditions. We present a dataset of flowering and maturity dates, recorded each year for one tree when available, or the average of several trees for each cultivar, over a period of 37 years (1978–2015). Such a dataset is extremely valuable for characterizing the phenological response to climate change, and the plasticity of the different cultivars’ behaviour under different environmental conditions. In addition, this dataset will support the development of predictive models for sweet cherry phenology exploitable at the continental scale, and will help anticipate breeding strategies in order to maintain and improve sweet cherry production in Europe.

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The European plum cultivar 'Opal', widely grown in Scandinavia, frequently initiates too many flowers and set too many fruits. If excess fruitlets remain on the trees until harvest, the crop consists of small, unmarketable fruits of low fruit quality and return bloom will be reduced. The current study investigated effects of different crop loads established at blossom and fruitlet stages on yield, fruit quality and return bloom. For two seasons starting in 2008 on mature 'Opal'/'St. Julien A' trees, two crop loads 50 and 25% flowers reduced were established at full bloom and at 10-12 mm fruitlet size and compared with an un-thinned control treatment. Treatments were applied on single whole trees in a randomized complete block design with six replications. Spindle trees spaced at 3.0×5.0 m were selected for uniformity in growth habit, flowering intensity and trunk cross sectional area. Final fruit set varied from 63% on the control trees to 18% when thinned at bloom. Yield was negatively correlated with the fruit set response. Thinning at the fruitlet stage resulted in smaller fruits at the same crop level compared to flower thinning. Fruit quality parameters characterized by bright yellow skin background colour, red surface colour and the concentrations of soluble solids increased significantly as the crop load was reduced. Other fruit quality parameters like percentage acidity were not significantly different and did not show a clear response to the thinning. Return bloom was promoted most when trees were thinned at bloom the year before.

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European plum cultivar Jubileum (Prunus domestica L.) blooms abundantly most years and too many fruit can be set if flowers and/or fruitlets are not properly thinned. In 2007, 2008 and 2009, mature ‘Jubileum/St. Julien A’ trees were treated with ethephon either at full bloom, at concentrations of 250, 375 and 500 mg/l or when fruitlets averaged ~12 mm in diameter at concentrations of 125, 250 and 375 mg/l. In general, flower-thinning treatments reduced fruit set significantly. Fruit set decreased with increasing ethephon concentrations, and the highest rate of ethephon applied either at full bloom (500 mg/l) or post bloom (375 mg/l) resulted in excessive over-thinning. Up to 375 mg/l of ethephon was required at full bloom whereas only 125 mg/l of ethephon was required post bloom for marked fruitlet thinning. Yields confirmed the fruit set response and yield reductions were significant. In most years, all thinning treatments resulted in fruit larger than 38 mm in diameter compared to fruit from unthinned control trees. Fruit quality, characterized by blue surface color and soluble solids content was generally higher and increased significantly with the reduction in crop load. Fruit firmness of fruit from all ethephon applications was lower than that of the fruit from unthinned control trees. In contrast, titratable acidity did not show a clear response to ethephon thinning. Return bloom the following year was mostly unaffected by all ethephon applications compared to the control. In conclusion, an ethephon application at a rate of up to 375 mg/l applied at full bloom will result in adequate thinning of ‘Jubileum’ plums and achieved a target of about 10- 15 % reduction in fruit set. When weather conditions are not conducive during flowering, a post bloom ethephon application at 125 mg/l may be applied however, this should only be considered in years of excessive flowering and as a last resort.

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When establishing an apple orchard it is important to stimulate the growth of young trees to fill up their allotted space in the row and minimize the time to come into full production with high quality fruit. In May 2012 two-year-old 'Summerred'/'M.9' knip trees were planted at the experimental farm at NIBIO Ullensvang, western Norway. The planting distance was 4×1 m (2500 trees ha-1). Three fertigation schemes were established (zero; low - 0.15 g N m-1 row day-1, and high nitrogen - 0.30 g N m-1 row day-1) and two crop loads allowed (low and high). In the year after planting the crop loads were limited to zero and five apples tree-1, respectively. In the third leaf the crop loads were adjusted by hand to 15 apples and 30 apples tree-1, respectively. The experimental design was a randomized blocks with four replications and 10 trees treatment-1. No significant effects of N-fertigation on soil NO3-, NH4+ or N-min contents were found. However, N-fertigation increased the leaf nitrogen content the whole season and leaf N were ≥ than the standard adequacy range (1.5-2.0%). Trees reached the desirable height of 3 m in the third leaf. Trunk circumference and number of branches per tree increased from second to third leaf, but were not significantly influenced by the N-fertigation. In the third leaf the high crop load trees yielded 7 kg tree-1 (17.5 t ha-1) and the low crop load 4 kg tree-1. Fruit weights were negatively correlated with the crop loads. Small differences in fruit quality attributes were found. Return bloom was not affected after the second leaf. However, the high crop load in the third leaf clearly reduced the amounts of return bloom in 2015, irrespective of the amount of N-fertigation.

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Prohexadione-Ca, an acylcylohexadione, is a plant growth retardant jointly developed by BASF, Germany and Kumiai Chemical Industry, Japan. In 2012, a trial on 11-year-old 'Aroma'/'M 9' apple trees growing on the experimental farm at NIBIO Ullensvang, western Norway was initiated. Trees were treated with prohexadione-Ca (trade name Regalis®, 10% prohexadione-Ca as active ingredient) 10 days after full bloom (June 6) at concentrations of 125 or 250 g ha-1; other trees were also sprayed 10 days after full bloom and again one month later (July 5) at the same concentrations and compared against an untreated control. Treatments were applied to individual whole trees in a randomized complete block design with four replications. Prohexadione-Ca treatments significantly reduced shoot growth of treated apple trees. Two treatments with 125 g or one treatment of 250 g reduced growth by ~80%. Prohexadione-Ca had little effect on yield and fruit quality. Shoot growth was also retarded in the year following application and this is attributed to a carry over effect of the prohexadione-Ca application(s).

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Triploid apple cultivars are often favored by human selection due to their increased fruit size, even though they possess higher requirements in terms of pollination compared to their diploid counterparts. However, similar to the sensory characteristics, preferences for the size and shape of apple fruit are not universal, but culturally dependent. In order to investigate the influence of selection pressure on the frequency of triploid genotypes among different traditional apple germplasms, 141 apple accessions maintained in ex situ collections in Norway and 115 traditional and international apple accessions from Bosnia and Herzegovina (B&H) were analyzed using 8 microsatellite markers. Genotypes possessing more than two alleles per locus were deemed to be triploid. The results of SSR analyses from this and comparable studies indicate that the triploid apple cultivars are much more frequent among the traditional apple germplasm from Southern Europe than they are among the traditional apple germplasm from Northern Europe. The possible causes for these results are also discussed.

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Apple genetic resources in Norway are currently conserved within a number of local clonal archives. However, during establishment of these ex situ collections, primary focus was not on capturing as much of the diversity as possible, but instead on preserving cultivars of particular importance to specific fruit-growing areas. To identify redun- dancies within the collection as well as to assess the genetic diversity and structure of apple germplasm currently being conserved in Norway, eight microsatellites were used in genetic characterization of 181 apple accessions. Overall, 14 cases of synonym or possibly mislabeled accessions were identified, as well as several homonyms and duplicates within and among the analyzed collections. The information obtained should contribute to overall better management of the preserved germplasm. Bayesian analysis of genetic structure revealed two major clusters, one containing most of the foreign cultivars, while the other consisted mainly of traditional Scandinavian cultivars, but also some very winter-hardy genotypes such as ‘Charlamovsky’, ‘Gravenstein’, ‘Transparente Blanche’, and ‘Wealthy’. Analyses of molecular variance (AMOVA) detected a signifi- cant genetic differentiation among the clusters ( fCT = 0.077; P < 0.01). The results of the Bayesian analyses do not indicate a strong differentiation between the foreign and the Norwegian apple accessions, however, they do suggest that climate adaptation has had a significant influence on the genetic structure of the preserved germplasm. Overall, apple accessions currently maintained ex situ in Norway represent a diverse germplasm which could be very valuable in future breeding programs, especially for the Scandinavian climate.

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The response of three-year-old 'Summerred' trees to crop load regulation by the chemical thinning agent Brevis® was tested in comparison with different levels of hand thinning. Brevis® was applied once or twice at a dosage of 1.1 and 2.2 kg ha-1 when fruitlets were approximately 15 and 19 mm in diameter at the time of the first and second application, respectively. All Brevis® applications significantly reduced the number of fruits tree-1. Both the single application of 2.2 kg ha-1 and the two-fold application of 1.1 kg ha-1 thinned the tree to the target crop load level of 30 apples tree-1. The degree of thinning by the single application of 1.1 kg ha-1 Brevis® did not significantly increase fruit weight and resulted in a very strong inhibition of return bloom similar to that observed in the untreated controls and trees hand thinned to 60 fruits tree-1. Return bloom was positively related to the level of thinning obtained. At the target fruit load of about 30 apples tree-1, return bloom was around 40% of the bloom in the year of the thinning trial. A further thinning to circa 15 fruits tree-1 increased return bloom to approximately 60%. In conclusion, 'Summerred' trees planted as two-year-old feathered trees should not bear more than 20 to 25 fruits tree-1 in their 3rd leaf in a northern climate to avoid the onset of biennial bearing and to ensure regular annual yields. Only then sufficient numbers of flower buds will develop to have the chance to obtain a good crop in the next year.

Sammendrag

Crop load adjustments in European plum trees (Prunus domestica L.) require thinning either by hand (mechanical) or chemical means to achieve marketable size, fruit quality and to overcome alternate bearing. Efficient tools for crop load management are highly desirable, since only a few chemical thinners are registered and hand thinning is labor intensive and costly. Gibberellic acid (GA3) was tested as a novel approach to regulate the crop load of the plum cultivar ‛Opal’ at Ullensvang, western Norway. The objective was to reduce flower bud induction in the “off-year” thus adjusting crop load the subsequent year. In 2008, an “off-year”, GA3 was applied to 9 year-old ‘Opal’ trees as a high volume spray to the point of run-off at 50 ppm or 100 ppm at either 5 weeks after full bloom or 10 weeks after full bloom, or on both dates and compared with untreated control trees. Trees were unthinned the first year but then thinned to commercial standard the following year. In the year of application, total yield was recorded and fruit quality evaluated. Return bloom, fruit set, yield and fruit quality were assessed the subsequent year. In general, there were no significant differences in crop load of all treated trees compared to untreated trees in the year of application (non-target crop) however, fruit weight increased slightly on those trees when GA3 was applied 5 weeks after full bloom compared to all other treatments and untreated trees. The following year (target crop) fruit set was significantly reduced for all GA3 treatments. The most effective application time was 5 weeks after full bloom. Before thinning, initial fruit set was greatest on untreated trees as well as on those trees treated with GA3 10 weeks after full bloom. Fruit weight and fruit colour were significantly better on trees with the least fruit set. GA3 applications had no effect on fruit firmness. It is concluded that GA3 is an effective tool for inhibiting flower bud induction in an “off-year” thus enabling crop load management the subsequent “on-year”.

Sammendrag

‘Summerred" apples (Malus domestica) Borkh are highly susceptible to biennial bearing if not properly thinned. This results in erratic yields and also affects fruit quality adversely. Between 2003 and 2005 ‘Summered"/‘M9" trees were treated with ethephon at concentrations of 250, 375 and 500 mL·L-1 when most king flowers opened (ca. 20% bloom) or at concentrations of 500, 625 and 750 mL·L-1 when the average fruitlet size was 10 mm in diameter. The experimental design was a completely randomised block design with 6 whole tree plots per replication. Trees were sprayed to the point of run-off with a hand applicator only when temperatures exceeded 15ºC. Within two weeks after the second application fruit set was reduced linearly with increasing concentrations of ethephon to less than 1 fruitlet per cluster at the highest concentrations used. Most thinning treatments reduced fruit set significantly compared to unthinned trees. Fruit numbers per tree decreased significantly with increasing ethephon concentrations, and the highest concentrations of ethephon applied during bloom or when the average fruitlet size was 10 mm in diameter resulted in over-thinning. Yield results confirmed the fruit set response where yield reductions were significant at highest concentrations of ethephon (2.1 kg·tree-1) compared to hand-thinned trees (7.3 kg·tree-1) in 2005. All thinning treatments resulted in higher percentage of fruits larger than 60 mm diameter average fruit size compared to unthinned control fruit. Thinning resulted in significantly higher soluble solid contents, and this was especially so for hand-thinned trees. Other fruit quality parameters like yellow/green background color did not show a clear response to thinning. Fruit firmness, however, decreased slightly in all ethephon treated trees whereas return bloom was improved on all thinned trees. It is recommended that ethephon be applied at a rate of 375 mL·L-1 when king flowers open or at a rate of 625 mL·L-1 when the average fruitlet size is 10 mm in diameter. These treatments thin ‘Summerred" apples to a target of about 5 fruits·cm-2 per trunk cross sectional area or 50-70 fruits·100 flower clusters-1 without impacting fruit quality, yield or return bloom the following year.

Sammendrag

In vitro dose responses of several calcium and potassium salts were determined on some commercially significant plant pathogens including: Helminthosporium solani, Fusarium oxysporum f. sp. pisi race 2, Colletotricum coccodes, Phytophthora cactorum, Phytophthora cinnamomi, Phytophthora erythroseptica, Phytophthora infestans, Phytophthora megasperma, Pythium ultimum and Venturia inaequalis. Mycelial growth inhibition was both salt-specific and dose-related. Pythium ultimum was completely inhibited by ≥75 mg·L-1 calcium propionate, but needed ≥ 300 mg·L-1 of calcium acetate and ≥ 40 mL·L -1 of potassium silicate for complete inhibition. Phytophthora infestans was completely inhibited by ≥150 mg·L-1 calcium acetate, ≥150 mg·L-1 calcium propionate or ≥ 5 mL·L-1 potassium silicate. Phytophthora cactorum was completely inhibited by ≥ 300 mg·L-1 calcium propionate, but required ≥ 600 mg·L-1 calcium acetate and ≥10 mL·L-1 potassium silicate for complete inhibition. Phytophthora cinnamomi was completely inhibited by calcium propionate at ≥ 600 mg·L-1, or by ≥10 mL·L-1 potassium silicate. Only potassium silicate inhibited Phytophthora megasperma, Phytophthora erthroseptica, V. inequalis and H. solani at concentrations of ≥ 5mL·L-1, ≥ 20 mL·L-1, ≥ 40 mL·L-1 or ≥ 80mL·L-1 respectively. Potassium acetate did not completely inhibit any of the pathogens in this study when tested at concentrations ≤ 1200 mg·L-1.

Sammendrag

This paper describes briefly the phenomena of alternate bearing of European plums and point out that more detailed investigations about physiological factors, in particular plant hormones, involved in the flowering process are of great importance.

Sammendrag

Fruit samples of seven sweet cherry cultivars grouped into three different groups of fruit flesh firmness (soft-fruited: 'Ranna Ljaskovska', 'Vista' and 'Sunburst', medium firm: 'Ulster' and 'Sylvia' and firm cultivars: 'Van' and 'Lapins') were harvested over a three week period with 3-4 d intervals prior to, during and after normal harvest time in 1997 and 1998 in Ullensvang, western Norway. Fruit firmness was measured at each harvest date along with measurements of soluble solids content (SSC), air temperature, precipitation and estimation of fruit colour. Corresponding samples picked at normal harvest date were stored in normal air atmosphere at temperatures 2 degrees C and 8 degrees C, respectively, and firmness was measured during storage with 3-5 d intervals. All the tested cultivars reached normal firmness, colour and SSC at harvest both years. Fruit were generally darker in 1998 than in 1997. All cultivars showed a more or less distinct reduction in firmness over the period prior to and slightly after normal harvest. Exceptions were 'Sunburst' in the 1998-season, that increased in firmness after normal harvest date, and the two firmest cultivars that increased in firmness over the ripening period in 1997. Generally, firmness increased during the first part of storage followed by a decrease after 1-2 weeks, the decrease being usually earlier and more distinct at 8 degrees C than at 2 degrees C. 'Van' in 1998 showed no change in firmness development throughout the storage period but a small increase in the last part. 'Lapins' in 1997 had however, a pronounced drop in firmness in the middle of the storage period followed by an increase. All the tested cultivars were more firm at normal harvest time in 1998 than in 1997, except the two firm-fleshed cultivars 'Van' and 'Lapins'. The warm and sunny 1997-summer produced softer fruits than the cold and rainy 1998-season, except for the firm-fleshed cultivars. It was anticipated that the many contradictory results of sweet cherry fruit firmness reported by other authors may be caused by differences in weather conditions as demonstrated.

Sammendrag

‘Elstar" is the latest-maturing commercial apple cultivar grown in Norway, with high fruit quality when properly managed. In May 2006, an experiment with four different crop loads [2, 4 ,6, or 8 flowers or fruitlets cm-2 trunk crosssectional area (TCSA), respectively] was established at two different stages [first bloom (FB), or 20-mm diameter fruitlets] and compared to unthinned control trees. Fruit growth was measured on individual fruit for each treatment throughout the season at weekly intervals. Thinning at FB gave a significantly lower final percentage fruit set than thinning to the same cropping level at the 20-mm fruitlet stage. However, fruit weights and soluble solids contents (SSC) were significantly higher, and the background fruit colour improved when trees were thinned at FB. The final number of fruit at harvest was less than the amount established at FB, or at the 20-mm fruitlet stage. There were significant differences between treatments in final fruit numbers per TCSA, which reflected the different crop loads. Fruit weights and SSC values were highest with the lowest crop load, and decreased with increasing crop loads.There was also a strong crop-load effect on the extent of return bloom per tree in the subsequent year. Trees thinned at FB had significantly more flower clusters than those thinned at the 20-mm fruitlet stage of. Untreated control trees had the lowest number of flower clusters. The amount of return bloom declined with increasing crop load. Second year crop loads and fruit weights were highest when trees were thinned at FB to two or four apples cm-2 TCSA in the previous year. Trees with the highest crop load had the lowest crop load in the following year. Fruit quality was generally high for all treatments.

Sammendrag

The European plum cultivar ‘Jubileum" blossoms abundantly most years and too many flowers can be set if not properly thinned.  For two seasons started in 2007 mature ‘Jubileum/St. Julien A  were treated with ethephon when full bloom opened at concentration of 250, 375 and 500 ppm and at 10-12 mm fruitlets stage at concentration of 125, 250 and 375 ppm. The experimental design was completely randomised with 6 replications of single trees. The trees were sprayed to run-off with a hand sprayer when temperature was above 15 ºC. All thinning treatments reduced the fruit set significantly.  The fruit set decreased with increasing ethephon concentration, and the highest rates at bloom and fruitlet overthinned. Less dosage of ethephon was required at fruitlet time in order to obtain the same fruit set. The yield did confirm the fruit set response and the yield reductions were significant. All thinning treatments gave higher percentage of fruits  larger than 38 mm fruit size compared to the unthinned control. Fruit quality characterized by  blue surface cover and the content of soluble solids was in general high and  increased significantly by reduced fruit. Fruit firmness, however, slightly declined in the ethephon thinned trees. Other fruit quality parameter like percentage acid content did not show a clear response to the thinning. Return bloom was little improved on thinned trees the following year. The crop load per tree was reduced to about the half of the previous year control trees included. In conclusion,  ethephon application at a rate of 375 ppm applied at full bloom or 250 ppm  at 10 mm fruit  diameter thinned ‘Jubileum" plums to a target of about 10 -15 % fruit set.    

Sammendrag

The performance of  26 different cherry rootstocks (‘Hexaploid Colt"," Damil",  ‘Tabel® Edabriz", ‘Gisela® (Gi) 3", ‘4", ‘5", ‘6", ‘7", ‘11", ‘Giessen (GI) 107/1", ‘148/13", ‘154/7" , ‘195/20", ‘318/17", ‘497/8", ‘523/02", ‘Weiroot (W) 10", ‘53", ‘158", ‘Maxma 14", ‘Maxma 60", ‘Maxma 97", ‘PHL-A", ‘PHL-B", ‘Piku®1"and ‘Piku® 3"), compared with ‘Colt" as a standard, for the cultivar ‘Lapins" (Prunus avium L), was assessed in a field trial in western Norway at 60° North. Trees, one-year-old whips, were planted in spring 1999; at 2.0 x 4.5 m spacing and trained to central leader as free spindle. Tree vigour, yield, fruit size, fruit quality and yield efficiency were evaluated for eight subsequent years. Tree sizes were significantly affected by the rootstocks after eight years growth. ‘Tabel®Edabriz", ‘Gi 3" and ‘Gi 4" produced the smallest and ‘Piku®3", ‘Colt"," Damil" and ‘Maxma 60" the largest trees as measured by trunk cross-sectional area (TCSA).  The most vigourus rootstock had five times larger TCSA than the dwarfest rootstocks. ‘Piku®1" was the most productive rootstock for this cultivar with highest cumulative yield followed by ‘Colt", ‘Piku®3" and ‘Gi 523/02". Average yield per tree and per year during the first seven cropping  years was 12 kg for ‘Piku®1". ‘Piku®1" and ‘Gi 5" induced early bearing.  Trees on ‘Gi 5" and ‘Gi 6"were the most yield efficient. Fruit size became significantly affected by the different rootstocks. In average for the different cropping years many of the Gi number selections, ‘Colt", ‘Damil" and ‘Piku®1"all  had a average fruit weight larger than 10 g per fruit. Fruit quality characterized by the content of soluble solids was in an average of 17.5 %. It was not influenced by crop load and did not differ much between trees on the various rootstocks. In conclusion, for high density production systems the most productive semi-vigorous rootstocks were ‘Colt"," Piku®3" and ‘Damil" and the semi-dwarf  Piku®1", ‘Gi 5" and "Gi 6". 

Sammendrag

Rain-induced fruit cracking in sweet cherries can be a major problem. In the Pacific Northwest, due to high labor costs, when fruit cracking exceeds 25% at harvest, fruit are not picked. OSU Horticulture and Pharmacy Faculty have collaborated in producing and patenting a novel, elastic, organic biofilm, SureSeal, which significantly reduced sweet cherry fruit cracking by up to 250% in Milton Freewater, Oregon and Loftus, Norway. Formulations of SureSeal are hydrophobic and consists of a copolymer of complex carbohydrates, phospholipids and calcium. Collaborative research undertaken over three years throughout the Pacific Northwest and overseas found that two applications of 1% SureSeal applied at straw color and again ten days later, reduced fruit cracking consistently when compared to untreated control fruit. Indeed, in Norway, fruit cracking was reduced from 24.6% to 9.8% when trees were treated with SureSeal in combination with plastic ground covers and a preharvest fungicide (fenhexamid). Furthermore, all these studies throughout Oregon and Idaho, found that SureSeal resulted in significantly (P

Sammendrag

The apple cultivar `Elstar" is the latest is the latest commercial maturing cultivar in Norway of high fruit quality when properly managed. In May 2006 a four years experiment with four different crop loads (2-4-6-8 flowers/fruitlets per TCSA cm2) were established at two stages (first bloom open and 20 mm fruitlets diameter) and compared to unthinned. Preliminary results from the two first seasons are presented. Fruit growth determination was conducted on individual fruits on each treatment during the season. Thinning at bloom to different crop levels gave a significant lower fruit set than thinning at the fruitlets stages to the same levels the first year. However, the fruit weight and the soluble solid contents were significant larger and ground colour improved when bloom thinning. The final fruit numbers at harvested was less than the amount established at bloom and fruitlets. There were significant differences between the different treatments in final fruits per TCSA and fruit set which reflected the different crop levels. Fruit weight and soluble solid contents were largest with lowest crop load and decreased with increasing crop levels. There was a strong crop load effect from the year before on the amounts of return bloom per tree. The trees thinned at bloom had significant more flower clusters than thinned at the fruitlet stage of 20 mm. The untreated, control trees had the lowest amount of flower clusters. The amount of return bloom declined with increasing crop load on the trees. The second year yield and fruit weight were larger when thinned at bloom. The highest crop load the second year was when thinned at bloom to the levels of 2 and 4 apples per TCSA the year before. The trees with the highest crop load the last year managed to give only a small crop. The fruit quality was in general high for all treatments.

Sammendrag

Fruktdyrking er en langsiktig produksjon med store etableringskostnader. Forståelig nok har ingen dyrker lyst til å satse på ukjente sorter som det er usikkert om vil bli godt mottatt av omsetning og forbruker. Norsk kjernefruktproduksjon har derfor hatt lite fornying i sortimentet de siste årene. Et nytt prosjekt skal forsøke å rette opp på dette. Prosjektet er et samarbeide mellom fruktdyrkere, omsetningen, forsøksringene og forskningen.

Sammendrag

Due to a late harvesting season compared to that found in other European countries, the sweet cherry industry in Norway is now expanding, aiming for export markets. Cultivars producing high quality fruit that ripen late (late July and throughout August) and that are suitable to grow in high density production systems are sought. In addition, early ripening cultivars are sought for local marketing in early and middle July. Testing cultivars and advanced selections has been carried out at Ullensvang Research Centre since 1959. During the last decade, 130 cultivars and advanced selections have been included in the testing program. Important parameters like fruit size, fruit firmness, low fruit cracking, high and precocious yield, fresh appearance and good flavour have been evaluated. Based on the results from this testing program, the following cultivars are currently recommended: a) for early season: `Burlat", `Moreau" and `Merchant", b) for mid-season: `Giorgia", `Chelan", `Samba", `Techlovan" and `Van", c) for late season: `Lapins", `Kordia", `Regina" and `Sweetheart".

Sammendrag

Some high density sweet cherry orchards in Norway suffer from decay of trees resulting in death or reduced vigour of trees. A survey monitoring healthy and infected trees from several orchards found differences between cultivars and rootstocks in sensitivity of tree decay. In order to investigate this cherry tree decay further, new field trials were established in 2002 with trees of the cultivar Van grafted on the two rootstocks Prunus avium seedling and Colt and trained as central leader trees. Two parallel trials were planted; one in the soil of an old cherry orchard and the other in the soil from agricultural land where no fruit production had been conducted in advance. During the first years significant larger annual vegetative growth measured as trunk girth, annual shoot growth and leaf areas were registered from the trees growing in the virgin soil. In the replanted cherry soil, trees grafted on the rootstock Colt grew more vigorously than the seedling rootstock based on leaf areas and shoot growth measurements. The rootstock Colt may be the answer for avoiding cherry replant diseases.

Sammendrag

Gibberellin er eit plantehormon som førekjem naturleg i høgare planter. Det fremjar særleg vekst, men har også innverknad på t.d. kvile, fruktsetjing og modning. I mange land vert søtkirsebærtrea sprøytte med den syntetisk framstilte gibberellinsyra GA3 3-4 veker føre hausting når fruktene er stråfarga (gule). Dette fører til at fruktene vert fastare, fargeutviklinga utsett og dermed modninga med opp til ei veke Gibberellin manglar praktisk utprøving i Noreg og er ikkje godkjent til kommersiell bruk. For å skaffa turvande dokumentasjon for offentleg godkjenning til yrkesdyrking i Noreg, vart det gjennomført biologisk utprøving ved Bioforsk Ullensvang i 2005 og 2006 og hjå dyrkarar i Lærdal og Telemark i 2005. Resultata viste at bioregulatoren GA3 utsette modninga med nær ei veke og gav fastare og større frukter hjå sortane Van og Lapins. Dette fører til ei meir robust frukt i marknaden. Lagringseigenskapane vart ikkje endra. Høveleg dosering er 20 ppm GA3 som ei sprøyting ved strå-gul farga kart.

Sammendrag

Histological properties of the graft union between a rootstock and scion may provide a mechanistic explanation why dwarfing rootstocks are able to reduce the growth of the tree. In order to investigate the relationship between growth and the amount of functional xylem tissue of potted sweet cherry trees, an experiment was conducted during 2002-2003. One year old field budded and bench grafted (from greenhouse) sweet cherry trees of the cultivars Van, Ulster and Lapins in all combinations of the three rootstocks Prunus avium seedling, Colt and Gisela 5 were grown in pots for two growing seasons. After shoot extension had terminated when trees were in full leaf the second year, the total growth of the different parts of the trees and the functional area using safranin staining were measured. The total mass production (tree dry weight, the length of two year old wood and number of leaves) was significantly larger in the budded trees. Similarly the trunk cross sectional area was significantly larger 10 cm above and in the middle of the graft union, but not 10 cm below it. The Colt trees were the most vigorous followed by the seedling and Gisela 5. Minor differences between the different cultivars were registered. Xylem staining with aqueous safranin combined with quantitative image analysis showed that the rootstock stem had a higher proportion of stained tissue than the scion stem. Sections taken in the middle of the graft tissue and 10 cm above showed that the proportion of stained tissue declined proportionally with the distance from the roots. The total area of stained stem xylem was larger for the two vigorous rootstocks compared to Gisela 5. Small differences were observed between cultivars and propagation methods.

Sammendrag

The performance of the plum rootstocks Marianna, Pixy and Wangenheim using St. Julien A as a standard to the cultivars `Avalon", `Edda", `Excalibur", `Jubileum", `Reeves" and `Victoria" was assessed in a field trial in western Norway at 60" North. Trees were planted in spring 1999, the plant material was one-year-old whips, spaced 2.0 x 4.5 m and formed with a central leader as free spindles. Soil management was grass in the alleyways and herbicide strips 1-m wide along the tree rows. Tree vigour, yield, fruit size and yield efficentcy were evaluated for the six subsequent years. Tree size was significantly affected by the rootstocks after six years growth. Wangenheim produced the smallest and St. Julien A and Pixy the largest trees as measured by trunk cross-sectional area in average for the different cultivars. St. Julien A and Pixy were the most productive rootstocks for the cultivars. However, Pixy produced significant larger yields per tree to the cultivar `Reeves" than St. Julien A. Trees on Pixy were the most yield efficient for all cultivars with the exception of `Victoria". The fruit sizes were in general large for all cultivars and became little affected by the different rootstocks. Fruit quality characterized by the content of soluble solids was in general high and did not differ between trees on the various rootstocks. The cultivar `Avalon" had the highest contents of soluble solids.

Sammendrag

During the period 2005-2006, trials with the bioregulator gibberellic acid (GA3) were conducted at Bioforsk Ullensvang in western Norway on mature sweet cherry trees. In 2005, unsprayed control trees of the cultivars `Van" and `Lapins" were compared with trees treated with one single application of 10, 20 and 30 ppm GA3 at the straw-yellow stage of fruit development. The same program was conducted the following year but included one extra application with 40 ppm GA3 to the cultivar `Lapins". Fruits were harvested when non-treated control fruits were mature, and again three times with 3 days intervals. At each harvest date a sub-sample of fruits were stored 3, 7, 10 and 14 days at 4ºC. Average fruit weight, fruit firmness, total soluble solids, fruit surface colour were determined for sub-samples of fruits at harvest dates and after storage. Fruit size was increased by near 1 g per fruit for both cultivars after GA3 application. Fruit firmness at harvest was not increased for the cultivar `Van" but responded linearly with increasing dosage of GA3 for the cultivar `Lapins". The maturity was delayed with half a week for "Van" and about one week for `Lapins" for all GA3 treated trees. The content of soluble solids was in general high and independent of the different treatments. Fruit size, firmness or soluble solid content were not influenced after storage and had market quality still after 10 days in cold store.

Sammendrag

During the period 1998-2000, thinning trials were conducted using bloom thinners on mature European plum trees at Ullensvang and at fruit growers sites in western Norway. In 1998, unsprayed control and handthinned `Victoria" trees were compared with trees treated at full bloom with a single application of 1% Armothin® or 1.5% ammoniumthiosulphate (ATS). The same program was conducted in the following two years with the addition of a single full bloom treatment with 250 ppm ethephon and a post-bloom application one month after full bloom with the mixture 10 ppm 1-napththaleneacetic acid (NAA) and 75 ppm ethephon. High volume sprays were conducted the first two years and low volume the last year. Thinning trials testing 1-1.5 % ATS and 5-7 % lime sulphur in comparison with unthinned and handthinned trees to the cultivars `Opal" and `Victoria" were conducted in 2000, at growers sites. Generally, thinning treatments reduced crop load and enhanced fruit quality (fruit size, soluble solid content, fruit firmness and ground and surface colour), but the results varied from year to year. Fruit set was reduced to about half of control values and the percentage of class 1 fruits was doubled compared to the control trees. High volume sprays to running off was more effective than low volume. The cultivar `Opal" was more sensitive to ATS than `Victoria" and a low dosage recommended. All thinning compounds caused some minor leaf injury but no fruit damage. The flower thinners were efficient at rather low temperture. No differences in the amount of gummosis (internal disorder of the fruits) were observed due to treatments on the `Victoria" plums. Return bloom was improved by thinning. In conclusion, a single dilute application at full bloom of 1% Armothin®, 1.5% ATS or 250 ppm ethephon or one application of the mixture 10 ppm NAA-75 ppm ethephon four weeks after bloom reduced fruit set and crop load and increased the fruit quality and return bloom to the cultivar `Victoria". Similar results gave one dilute spray with 1 % ATS or 5 % lime sulphur at full bloom to the cultivar `Opal".

Sammendrag

Betre lystilhøve i frukttrea aukar veksten hjå tre og frukter, og fruktkvalitetsfaktorar som farge og oppløyst turrstoff vert betre. Sjølv om daglengda under norske veksttilhøve er lang, er den samla lystilgangen mindre enn på sørlegare breiddegrader pga den korte vekstsesongen. Metodar som aukar ljostilgangen, t.d. lysreflekterande duk under trea, vil vera gunstig for norsk fruktdyrking. Ein har prøvd ein voven plast duk (Extenday (R)) i frukthagar på Vestlandet. Der radavstanden var 4 m, har ein strekt ut 3m brei duk på bakken langs køyregangane og festa med gummiband til trea på kvar side. Der radavstanden var 5 m, nytta ein 4m brei duk. Duken låg ute frå midten av juni til etter hausting. Det var ingen temepratureffekt av duken. Men det var 5 gonger så mykje lys i trekruna hjå tre som sto i felt med reflekterande duk i høve til kontroll tre. I køyregangen var det 3 gonger så mykje lys over duk som i køyregangar med gras. I Aroma var eple frå tre frå felt med duk større, søtare og med meir raud dekkfarge enn frå kontroll trea. Det var særleg stor skilnad frå eple på dei nedte greinene. Med omsyn til fastleik og syreinnhald var det ikkje sikre skilnader. Men Streif-indeks viste at refleksduken framskunda mogninga.

Sammendrag

I eit felt med "Excalibur" og "Prinlew" plommer vart køyregangen dekka med kvit reflekterande duk for å betra ljostilhøva i trekruna. Duken låg i hagen frå 2 veker etter bløming til etter at plommene var hausta i midten av september. Der det ikkje var nytta reflekterande duk var fruktene nede på treet grønare, hadde mindre dekkfarge og lågare innhald av oppløyst turrstoff enn fruktene oppe i trekrunene. Fruktene frå tre som hadde stått over reflekterande duk var like godt farga og hadde same syrinnhald og fastleik om dei var hausta oppe eller nede på trea. Men det var også for desse trea høgare innhald av oppløyst turrstoff i fruktene oppe i trea i høve til dei som hadde vakse nedst i trea. Reflekterande duk gav jamnare mogning hjå plommene oppe og nede i trea. Dermed kan ein klara seg med færre haustingar. Temperaturen var ikkje heva der ein nytta duk, og duken svekka grasveksten i køyregangane.

Sammendrag

Viktige eigenskapar til ei grunnstamme er å regulera veksten og gje store og jamnte avlingar av kvalitetsfrukt. Gjennom eit stort foredlingsarbeid i fleire land i Europa dei siste 10-åra, har det lukkast å foredla fram ei rad grunnstammer med moderat vekst, tidleg bering og god bereevne. Denne rapporten omtalar resultat av utprøving av 27 ulike grunnstammer med redusert vekst til søtkirsebærsorten Lapins gjennomført ved Bioforsk Ullensvang i åra frå 1999-2006. Dette er del av eit europisk samarbeidsprosjekt der 11 land er med.

Sammendrag

Viktige eigenskapar til ei grunnstamme er å regulera veksten og gje store og jamne avlingar av kvalitetsfrukt. Gjennom eit stort foredlingsarbeid i fleire land i Europa dei to siste 10 åra, har det lukkast å foredla fram ei rad grunnstammer med moderat vekst, tidleg bering og god bereevne. Denne rapporten omtalar resultat av utprøving av 27 ulike grunnstammer med redusert vekst til søtkirsebærsorten Lapins gjennomført ved Bioforsk Ullensvang i åra frå 1999-2006. Dette er del av eit europisk samarbeidsprosjekt der 11 land er med.

Sammendrag

Combinations of covering and fungicide applications were tested on two sweet cherry cultivars; Van during two years (2001 and 2002) and Lapins three years (2001"2003). The following treatments were tested in 2001 and 2002: (i) covering during flowering and from 5 to 6 weeks prior to harvest and throughout harvest, no fungicides applied, (ii) as (i) but fungicides were applied once or twice between the two covering periods, (iii) covered 5 to 6 weeks prior to harvest and throughout harvest, fungicides applied two or three times prior to covering, and (iv) uncovered throughout the season, fungicides applied two or three times in the period from flowering towards harvest. In 2003, the trees were covered only from 5 to 6 weeks prior to harvest and throughout harvest. Both treatments that year received fungicide applications during flowering, but one of the treatments was left unsprayed during the green fruit period prior to covering. Every combination of covering and fungicide applications reduced total fruit decay at harvest significantly compared to a full fungicide programme and no covering. In three of four trials when the trees were covered during flowering and prior to harvest, and fungicide applications were omitted in the green fruit phase between the covering periods, no significant increase in fruit rot occurred compared to treatments where fungicides were applied. However, in one trial there was a significant increase in fruit rot by leaving out one fungicide spray during that intermittent period. Furthermore, if fungicides were only applied during flowering and not on green fruit before covering in 2003, a significant increase in fruit rot occurred. Thus, leaving out fungicide applications during that supposedly less susceptible green fruit period, increased the risk of acquiring fruit rot. Applying fungicides during the green fruit stage significantly reduced the amount of brown rot in four of five trials and anthracnose in one of five trials. No negative effect on fruit quality was found from the extended covering periods. It can be concluded that covering effectively replaced fungicide applications during flowering and prior to harvest.

Sammendrag

I feltforsk ved Bioforsk Ullensvang har det vorte gjennomført utprøving av grunnstammene Marianna GF 8-1, Pixy , Wangenheim og St. Julien A poda på plommesortane Avalon, Edda, Excalibur, Jubileum, Reeves og Victoria. Tre vart planta som grønpisker sommaren 1999 med 2 x 4,5 m planteavstand og forma som spindeltre. Trea vart stelte som ei tradisjonell handelsplanting. Trea kom i bering i 2002. Årleg har det vorte registert stammetverrmål, avling og fruktkvalitet. Grunnstammene regulerte tilveksten til dei ulike sortane. Størst tilvekst på trea gav grunnstammene St. Julien A og Marianna GF 8-1 i middel for dei seks sortane. Wangenheim var den mest svaktveksande grunnstamma. Samla for dei fire første avlingsåra gav grunnstammene St. Julien A og Pixy størst avling bortsett for til sorten Excalibur. Til sorten Reeves gav Pixy størst avling. Sortane Victoria og Avalon gav høgaste avling og Edda lågast i middel av desse fire grunnstammene. Fruktstorleiken var ikkje påverka av dei ulike grunnstammene. Sortane Avalon, Excalibur, Reeves og Jubileum hadde størst frukter. Innhaldet av oppløyst tørrstoff var generelt høgt for alle sortane og var ikkje påverka av dei ulike grunnstammene. Sortane Edda og Avalon hadde høgast innhald av oppløyst tørrstoff.

Sammendrag

Epleavlingane varierer frå år til år på grunn av vekselbering der avlinga i bereåret er mykje større og ofte med redusert fruktstorleik og kvalitet enn i kvileåret. Avlinga kan regulerast med kjemiske middel eller med hand under blomstringa eller på kartstadiet. I det 3-årige prosjektet” Vekselbering i eple - årsaker og tiltak” vart det gjennomført mange feltforsøk med å etablera optimale avlingar med hand eller kjemisk. Indre Hardanger Forsøksring var prosjekteigar og med Planteforsk Ullensvang som fagleg prosjektleiar. Fire ulike avlingsnivå vart etablerte med hand under både blomstringa og ein månad seinare i tre samanhengande år på dei same trea på eplesortane Summered og Aroma. Dei trea der avlingspotensialet vart fjerna heilt anten ved å ta bort alle blomane eller karten, gav flest blomeklasar pr tre året etter jamført med tre som hadde avling. Blometalet pr. tre vart sterkast redusert året etter di høgare avlingsnivået var og di seinare avlingsreguleringa vart utført. Fruktene var størst ved tynning under blomstringa. Fruktvekta og mengda av oppløyst tørrstoff i fruktene vart redusert med aukande avlingsnivå på trea. Høveleg avlingsnivå med god fruktkvalitet for eplesortane Aroma og Summered poda på grunnstamma M9 er om lag 6 frukter pr. cm2 stammetverrmål. Dette svarar til eit frukttal pr. tre som er om lag lik planteavstanden mellom trea i cm. Tynningsmidlane Cerone (ethephon), ATS (ammoniumthiosulfat), soyaolje og MaxCel (plantehormonet 6-benzyladenin) vart prøvde til fleire eplesortar. Cerone regulerte avlinga ved sprøyting både under blomstringa og på karten. Kvaliteten vart heva og mengda med blomsterknoppar vart auka på trea året etter. Middelet er krevjande i bruk med krav til rett dosering og temperatur og eplesortane har ulike doseringskrav. ATS gav variabelt tynningsresultat med i tillegg noko skade (sviding) av bladkantar. Både soyaolje og MaxCel gav for svak tynningseffekt.

Sammendrag

Rain covers protect sweet cherries against rain cracking and reduce disease pressure. It is important in order to achieve high quality sweet cherries in many cherry-producing regions worldwide. Many different designs to variable costs are available at the market. Tree covers that are wind stable and economically feasible are a demand for the fruit growers.

Sammendrag

The performances of the plum rootstocks Plumina® Ferlenain, Ishtara® Ferciana, Jaspi® Fereley and the pentaploid open pollinated seedling of Mariana P 8-13 compared with St. Julien A as a standard, for the cultivars "Opal" and "Reine Claude GF 1119" were assessed in a field trial in western Norway at 60" North. This trial was one part of an international plum rootstock trial located in seven European countries and organized from INRA Bordeaux. Trees were planted in spring 1994; spaced 2.0 x 4.0 m and formed with a central leader as free spindles. Soil management was grass in the alleyways and herbicide strips 1-m wide along the tree rows. Tree vigour, yield, fruit size and yield efficiency were evaluated for the seven subsequent years. Tree size was significantly affected by the rootstocks. P 8-13 produced the largest trees for both cultivars as measured by trunk cross-sectional area. The smallest trees were produced on Plumina® Ferlenain for the cultivar `Opal" and on Jaspi® Fereley for `Reine Claude". The cultivar `Opal" was the most productive and gave three times larger crop than "Reine Claude" on average for the six cropping years. The "Reine Claude" trees came two years later into production than "Opal". There were small differences between the different rootstocks in productivity: However, the rootstock Plumina® Ferlenain produced significant lower crop than the other rootstock for `Opal". Trees on Jaspi® Fereley were the most yield efficient for `Opal" and Plumina® Ferlenain for `Reine Claude". The fruit sizes were in general medium to small for both cultivars and became little affected by the different rootstocks. The average fruit size was about 29 g for `Opal" and 22 g for `Reine Claude". Fruit quality characterized by the content of soluble solids was high for `Reine Claude" with average 20 % and 15 % for `Opal" and did not differ much between trees on the various rootstocks.

Sammendrag

The performances of the plum rootstocks Ferlenain, Ishtara, Jaspi and P 8-13 compared with St. Julien A as a standard, for the cultivars `Opal" and `Reine Claude GF 1119" were assessed in a field trial in western Norway at 60° North. This trial was one part of an international plum rootstock trial located in seven European countries and organized from INRA Bordeaux. Trees were planted in spring 1994; spaced 2.0 x 4.0 m and formed with a central leader as free spindles. Soil management was grass in the alleyways and herbicide strips 1-m wide along the tree rows. Tree vigour, yield, fruit size and yield efficiency were evaluated for the seven subsequent years. Tree size was significantly affected by the rootstocks. P 8-13 produced the largest trees for both cultivars as measured by trunk cross-sectional area. The smallest trees were produced on Ferlenain for the cultivar `Opal" and on Jaspi for `Reine Claude". The cultivar `Opal" was the most productive and gave three times larger crop than "Reine Claude" on average for the six cropping years. The `Reine Claude" trees came two years later into production than `Opal". There were small differences between the different rootstocks in productivity: However, the rootstock Ferlenain produced significant lower crop than the other rootstock for `Opal". Trees on Jaspi were the most yield efficient for `Opal" and Ferlenain for `Reine Claude". The fruit sizes were in general medium to small for both cultivars and became little affected by the different rootstocks. The average fruit size was about 30 g for `Opal" and 25 g for `Reine Claude". Fruit quality characterized by the content of soluble solids was high for `Reine Claude" with average 20 % and 15 % for `Opal" and did not differ much between trees on the various rootstocks.

Sammendrag

Observasjonar om blomstringstid, blomstermengd og fruktsetting vart innsamla frå sortsprøvefelta i søtkirsebær ved Bioforsk Ullensvang forskingssenter i perioden 1993 – 2005. Sortane var poda på grunnstammene Colt, Prunus avium L. frøstamme og Gisela 5. Det var tydelege skilnader i blomstringstid og - mengd mellom dei ulike sortane, mellom tre på ulike grunnstammer og åra. Blomstringstida har starta tidlegare i dei siste åra. Dei mest avlingssikre sort/grunnstamme-kombinasjonane har både høg blomstermengd og fruktsettingsgrad. Ei oppdatert liste over kva sterilitetsgruppe sortane høyrer heime i er presentert.

Sammendrag

I den seine norske plommesesongen saknar ein gode kvalitetssortar. Mildare vêr i siste halvdel av september og fyrst i oktober i seinare år, gjer at sortar som modnar sist i september er meir aktuelle og dyrka enn før. Den kanadiske plommesorten Valor har vorte dyrka i grannelanda våre i dei siste åra og er kjenneteikna med tidleg og stor avling og med mørkeblå, store frukter av høg kvalitet. Innleiande prøvedyrking av denne plommesorten ved Bioforsk Ullensvang stadfester desse eigenskapane.

Sammendrag

Regn føre og under haustinga fører til at søtkirsebær sprekk, vert meir utsett for ymse rotesoppar og kan dermed ikkje seljast til friskkonsum. Det er difor både ålment akseptert, men også lønsamt i mange land å byggja fysiske vern for å hindra skade av nedbør. Ulike modeller er tilgjengeleg på marknaden frå det heilt enkle til det mest avanserte som er å dyrka søtkirsebær i plasthus. Denne artikkelen gjev ein kort omtale av ulike tekniske måtar å dekka søtkirsebæra.

Sammendrag

Kompost frå våtorganisk avfall omdanna i reaktor har vorte prøvd i ulike mengder og modningsgrader i feltforsøk med eple og jordbær ved Planteforsk Ullensvang. Fersk kompost vart lagt i trerekkja i ei stripe på 1 m under epletre i 5, 10 og 15 cm tjukt lag som svarar til om lag 5, 10 og 15 tonn kompost pr. daa. Året etter vart forsøksrutene delte i to og ein halvparten fekk same handsaminga som året føre med ny tilføring av kompost. Eit dekke med 10 cm fersk kompost i frukttrerekkja hemma oppspiring av frøugras i ein vekstsesong. Komposten frigav lite av dei lettløyseleg minerala kalium, fosfor, magnesium og kalsium til jorda første vekstsesongen. Men nitrogenet vart frigjort og teke opp i trea proporsjonalt med mengda av kompost tilført. Ny tilføring av kompost andre året førte til markert auke i jordreaksjonen og dei lettløyselege næringsemna i jorda, men ikkje til auka opptak i plantene. I eit nytt feltforsøk vart ei mengd på 2,8 og 8 tonn kompost pr. daa av både fersk og mogen kompost lagt ut i planterekkja til etablerte epletre av sorten Gravenstein. Fersk kompost verka mest spirehemmande på ugraset første året. Tilføring av ulike kompostmengder påverka lite fruktkvaliteten. Tilføring av størst mengd med kompost frigav lettløyseleg kalium, kalsium og fosfor til jorda og heva pH andre året. Det vart frigjeve lite nitrogen til jorda. Opptaket av ulike næringsemna i trea var lite påverka av ulike mogningsgrader og mengder. I eit feltforsøk med jordbærsorten Korona vart det tilført 5, 10 og 15 tonn pr. daa med fersk og mogen kompost føre planting. Store kompostmengder iblanda i jorda hjå jordbær hemma planteveksten etter planting og jordoverflata og planter vart dekte med soppvekst. Verknad var størst av den ferske og dei største mengdene med kompost. Ulike mengder med fersk og mogen kompost reduserte jordbæravlinga første avlingsåret, men ikkje det andre då avlinga var generelt høg. Bærstorleiken var lite påverka første året, men var større i dei komposthandsama rutene året etter. Begge åra var roteprosenten for høg og då særleg der det var kompost. Det vart ikkje påvist auka opptak av ulike tungmetall i bær som vaks i kompostblanda jord første avlingsåret. Komposten heva pH i jorda og innhaldet av lettløyseleg kalsium, kalium og fosfor i jorda, men lite av magnesium. Nitrogeninnhaldet i jorda var lite påverka verken av modningsgrad og mengder av kompost. Kompost iblanda i jorda førte til at jordbærplantene auka opptaket av nitrogen og kalium, men mindre med fosfor, kalsium og magnesium. Opptaket var proporsjonalt med tilført kompostmengd.

Sammendrag

Kjemisk tynning med Cerone med ei dosering på 0,05-0,075 % når midtblomen var open eller 0,125-0,150 % ved 10-12 mm kartdiameter tynnte eplesorten Summerred tilfredstillande og auka blomstermengda året etter. Høveleg nivå er ei tynningsgrad på kring 5 frukter pr. cm2 stammetverrmål eller 50-70 frukter pr. 100 blomsterstandar. Fruktene vart større ved tynning ved byrjande blomstring.

Sammendrag

Dyrkingseigenskapar av 21 søtkirsebærsortar vart vurderte ved Bioforsk Ullensvang: Fylgjande søtkirsebærsortar har gode eigenskapar: Chelan, Giorgia, Samba, Techlovan og Van med modning i siste veka i juli og Lapins, Kordia, Regina og Sweetheart sist i sesongen. I tillegg er Stardust aktuell sort med ljos raud dekkfarge.

Sammendrag

Fruktdyrkarane i Nederland legg vekt på å oppretthalda ein god næringsbalanse i treet i heile vekstsesongen. Til dette nyttar dei seg av både jord- og bladgjødsling. Skal dette lukkast, er det viktig at vasstilførselen er optimal. Ulike praktiske rådgjerder er omtalte

Sammendrag

Ei feltforsøk med intensive plantesystem med plommesortane `Edda", "Opal" og "Mallard" (Prunus domestica L.) poda på grunnstamma St. Julien A vart planta i 1993 ved Bioforsk Ullensvang. Fire ulike plantesystem (vertikal akse, fri spindel, hekk og Y-forma og tre plantetettleikar (0.5, 1.0, 1.5 x 4 m ) for dei Y- og hekk- forma trea og 2.0 x 4 m for dei to andre treformene vart prøvde. Trea hadde god tilvekst med tidleg avling. Stammearealet på trea auka proporsjonalt med planteavstanden og avlinga med plantetettleiken. Etter ni år var avlinga størt hjå dei Y-forma trea med tettaste planteavstand. Det var ikkje funne skilnad i fruktstorleiken hjå dei ulike soratene mellom dei ulike treformene eller plantetettleikane. Innhaldet av oppløyst tørrstoff i fruktene var generelt høgt. Sorten "Opal " hadde dei minste fruktene og lågare innhald av oppløyst tørrstoff enn dei andre sortane.

Sammendrag

Covering sweet cherry trees (Prunus avium L.) with plastic prior to harvest is used to prevent fruit cracking. The most commonly used covering system in Norway is a frame of wooden poles, which support a three-wire system. Removable plastic sheets lying as a flat roof above the trees are connected to the wires. Covering for 3 weeks prior to harvest reduced fungal fruit decay from 10 to 1% and from 50 to 10% in two years, respectively. Important fungal diseases causing fruit decay in Norway are brown rot, gray mold, bitter rot and Mucor rot. By covering the trees for five to six weeks prior to harvest (commercial practice is three to four weeks), one to two fungicide applications could be omitted. If the trees were covered all the time from flowering to harvest, all fungicide applications could be omitted without any increase in fruit decay. Extended periods of covering did not lower fruit quality. Sweet cherries are most susceptible to fruit decaying fungi during flowering and towards harvest. In a series of experiments, fruits were covered at those two periods and left uncovered during the less susceptible green fruit phase (ca. 5 weeks). Covering could replace fungicide sprays without any increase in fruit decay, but leaving out fungicide sprays on uncovered green fruits increased the amount of brown rot in three of four experiments. From numerous experiments we will conclude that use of rain protective cover is a powerful alternative to fungicide applications in sweet cherry.

Sammendrag

Ein har studert samanhengen mellom avling, klimafaktorar og fruktkvalitet i plomme. Avling vart vurdert etter ein 1-5 skala, ein har nytta klimaparametrane månadsgjennomsnittstemperatur og månadssumnedbør og fruktkvalitet er målt som innhald av oppløyst turrstoff. Målingane er gjort i 19 år og omfattar 11 sortar.  Hjå 8 av 11 sortar var det ein sterk negativ korrelasjon mellom avling og fruktkvalitet. Fruktkvaliteten var positivt relatert til varmt turt ver i april og juni, og til kjølig vått ver i mai. I forsøket på Ås fann ein negativ korrelasjon mellom julitemeperatur og fruktkvalitet, medan ein i Hardanger fann at varmt turt ver i juli betra fruktkvaliteten.

Sammendrag

Due to a late harvesting season compared to that found in other European countries, the sweet cherry industry in Norway is now expanding, aiming for export markets. Cultivars producing high quality fruit that ripen late (late July and throughout August) and that are suitable to grow in high density production systems are sought. In addition, early ripening cultivars are sought for local marketing in early and middle July. Testing cultivars and advanced selections has been carried out at Ullensvang Research Centre since 1959. During the last 6 years, approximately 130 cultivars and advanced selections have been included in the testing program. Important parameters like fruit size, fruit firmness, low fruit cracking, high and precocious yield, fresh appearance and good flavour are evaluated. Based on the results from this testing program, the following cultivars are currently recommended: a) for early season: `Burlat", `Moreau" and `Merchant", b) for mid-season: `Giorgia", `Chelan", `Samba", `Techlovan" and `Van", c) for late season: `Lapins", `Kordia", `Regina" and `Sweetheart".

Sammendrag

Some high density sweet cherry orchards in Norway suffer from decay of trees resulting in death or reduced vigour of trees. A survey has been conducted monitoring healthy and infected trees from several orchards. The nutritional statuses of the soil and in the trees were in general in accordance with general accommodation. Different species of root nematodes were identified with levels above the damage of thresholds. Neither insects, diseases, bacterials nor virus were registered as the main reason for this dieback. However, differences between cultivars and rootstocks sensitivity were observed. In order to investigate this cherry tree decay further, new field trials were established in 2001 with trees of the cultivars Van and Kristin grafted on the two rootstocks Prunus avium seedling and Colt and trained as a central leader trees. Two parallel trials were planted; one in the soil of on old cherry orchard and the other in the soil from agricultural land where no fruit production has been conducted in advance. During the first years significant larger annual vegetative growth measured as trunk cross sectional area and annual shoot growth were registered from the trees growing in the agricultural soil. In the replanted cherry soil, trees grafted on the rootstock Colt grew more vigorously than the seedling rootstock based on leaf areas and shoot growth measurements. The first significant crop is expected in 2005.

Sammendrag

Søtkirsebærproduksjonen i Sør-Afrika er prega av pioner-ånd. Dyrkarane satsar stort, men har mange utfordingar slik som klimatiske avgrensingar, redusert tilgang på rett plantemateriale og plantevern-rådgjerder, og dei manglar både offentleg støtta forskings- og utviklingsprogram og rådgjeving. Økonomisk er dette likevel interessant, sidan det vert betalt gode prisar for søtkirsebær i ein periode med lite utbod av denne vara.

Sammendrag

Denne artiklen gjer greie for resultat frå feltforsøk med fire grunnstammer og seks plommesortar ved Planteforsk Ullensvang. Dette gjeld grunnstammene Pixy, Wangenheim og Marianna med St. Julien A som målestokk og sortane Edda, Avalon, Excalibur, Victoria, Reeves og Jubileum.

Sammendrag

Sweet cherry trees sometimes suffer from dieback symptoms under Scandinavian growing conditions. Some combinations of cultivars and rootstocks are more susceptible to this than others. The graft union between a rootstock and a scion is a junction between two different tissues. Differences in tissue development in the union may provide a mechanistic explanation of inhibiting transport of water and nutritional substances and likely inhibit growth of the scion. In order to investigate the relationship between growth and the amount of functional xylem tissue of potted sweet cherry trees, an experiment was conducted during 2002-2003. One year old field budded and bench grafted (from green house) sweet cherry trees of the cultivars Van, Ulster and Lapins in all combinations of the three rootstocks Prunus avium seedling, Colt and Gisela 5 were grown in pots for two growing seasons. After shoot extension had terminated when trees were in full leaf the second year, the total growth of the different parts of the trees and the quantification of functional area using safranin staining were conducted. The total mass production (tree dry weight, the length of two year old wood and number of leaves) was significant larger in the budded trees. Similarly the trunk cross sectional area was significant larger 10 cm above and in the middle of the graft union, but not 10 cm below. The Colt trees were the most vigorous followed by the seedling and Gisela 5. Small differences between the different cultivars were registered. Xylem staining with aqueous safranin combined with quantitative image analysis showed that the rootstock stem had a higher proportion of stained tissue than the scion stem. Sections taken in the middle of the graft tissue and above showed that the proportion of stained tissue declined proportionally with the distance from the roots. The total area of stained stem xylem was larger for the two vigorous rootstocks compared to Gisela 5. Small differences were observed between cultivars and propagation methods.

Sammendrag

Trees of `Discovery" apples growing on dwarf and semi-dwarf rootstocks were assessed in field trials at two sites (western and eastern Norway) at 60° North. The rootstocks included two selections of M.9 (EMLA, RN.29), two from the Polish (P) series (P.59, P.60), three from the Geneva (G) series (G.30, G.78730-026, G.202) and M.26. Trees were planted in the spring 1997 as two years old feather trees, spaced 1.5 x 4 m, trained as slender spindles and evaluated for five subsequent years. Soil management were grass in the alleyways and herbicide strips 1-m wide along the tree rows. Tree size was significantly affected by the rootstocks after five years growth. P.59, G.78730-026 and M.9 RN.29 produced the smallest and G.30 and G.202 the largest trees as measured by trunk cross-sectional area. P.59 and G.30 had the greatest yields per tree, followed by G.202, P.60 and M.9 EMLA. Trees on P.59 were the most yield efficient followed by the two M.9 clones. The fruit density measured as number of fruits per trunk-cross-sectional area showed similar results. The different rootstocks affected little the fruit weights. Fruit quality characterized by the content of soluble solids was in general high and did not differ between trees on the various rootstocks.

Sammendrag

The performance of the plum rootstocks Marianna, Pixy and Wangenheim using St. Julien A as a standard to the cultivars Avalon, Edda, Excalibur, Jubileum, Reeves and Victoria Naa was assessed in a field trial at western Norway at 60° North. Trees were planted in spring 1999 and evaluated for the five subsequent years. The plant material was one year old whips, spaced 2.0 x 4.5 m and formed with a central leader as free spindles. Soil management were grass in the alleyways and herbicide strips 1-m wide along the tree rows. Tree size was significantly affected by the rootstocks after five years growth. Wangenheim produced the smallest and St. Julien A and Pixy the largest trees as measured by trunk cross-sectional area in average for the different cultivars. Pixy produced the largest yields per tree to the cultivars Edda, Excalibur and Reeves while St. Julien A was the most productive to Avalon, Jubileum and Victoria Naa. Trees on Pixy were the most yield efficient for all cultivars with the exception of Victoria Naa. The fruit sizes were in general large, but became affected by the different rootstocks to some extent. Depending on the cultivar, fruit size was favourable affected by Pixy and St. Julien A, while trees on Marianna produced the smallest fruits. Fruit quality characterized by the content of soluble solids was in general high and did not differ between trees on the various rootstocks. The cultivar Avalon had the largest amounts of soluble solids.

Sammendrag

Alternate bearing is a major problem for the Norwegian apple industry. Due to over-cropping one year where fruit size and quality are reduced, the trees are likely to turn into a pattern with high and low yield every second year. This inconsistent yield pattern provides problem for both the growers and the market. Commercial practise is to remove the excessive flowers or fruitlets by chemicals or by handthinning. The only officially registered agents for apple thinning are ethephon and ammoniumthiosulphat. The growers find them unpredictable in use and more knowledge is wanted in order to give more precisely thinning recommendations. A new project started at Ullensvang Research Centre in 2003. It will last for three years and focus on optimising the crop loads and test different thinning agents under bloom and at different fruitlet stages. Different crop levels will be established during and after bloom by hand adjusted by trunk cross sectional area. The experimental trees will be monitored during a 3-year period. Traditional pomological observations will be registered included storage of the fruits where fruit quality will be measured. Leaf areas per tree will be calculated using an area meter. In addition different thinning chemicals will be tested according the program to the working group of European Fruit Research Institute Networks. Emphasis will be put on concentration and thinning periods of the agents ethephon, ammoniumthiosulphat and compounds that could be approved for organic growing like colza oil. Results from the 2003 season will be presented.

Sammendrag

During the period 1998-2000, thinning trials were conducted using bloom thinners on mature European plum trees at Ullensvang Research Centre in western Norway. In 1998, unsprayed control and hand-thinned `Victoria" trees were compared with trees treated at full bloom with a single application of 1% Armothin® or 1.5% ammoniumthiosulphate (ATS). The same program was conducted in the following two years with the addition of a single full bloom treatment with 250 ppm ethephon and a post-bloom application one month after full bloom with the mixture 10 ppm 1-napththaleneacetic acid (NAA) and 75 ppm ethephon. Generally, thinning treatments reduced crop load and enhanced fruit quality (fruit size, soluble solid content, fruit firmness and ground and surface colour), but the results varied from year to year. Fruit set was reduced to about half of control values and the percentage of class 1 fruits was doubled compared to the control trees. All thinning compounds caused some minor leaf injury but no fruit damage. No differences in the amount of gummosis (internal disorder of the fruits) were observed due to treatments. Return bloom was improved by thinning.

Sammendrag

Fruktene nede og inne i frukttrekruna er mindre mogne med dårlegare fargeutvikling enn fruktene i toppen av frukttrea. Dette skuldast fyrst og fremst redusert ljostilgang. Ein reflekterande duk på bakken under plommetrea vil auka ljostilgangen og gje plommer med betre kvalitet og jamnare mogning. Målingar i vekstsesongen viste at den reflekterande duken gav meir ljos, medan ein ikkje registrerte auka temperatur i tre som vaks over reflekterande duk. Plommer dyrka over reflekterande duk hadde høgare innhald av oppløyst turrstoff, mindre syre og betre fargeutvikling samanlikna med kontrollen. Skilnaden var meir markert i nedre del av trea. Graset under duken var svekka, og i traktorspora gjekk graset ut.

Sammendrag

Feltforsøk med plommesortane Edda, Opal og Mallard poda på grunnstamma St. Julien A gjennomført over 9 år med fire ulike kruneformer (akse-forma, fri spindel, hekk og Y-forma) og tre ulike planteavstandar (125-500 tre pr. da). Dei første avlingsåra auka avlinga med plantetettleiken. Akkumulert avling var høgast for dei hekk- og Y-forma trea. Det var små skilnader mellom i fruktkvalitet mellom dei ulike sortane, kruneformene og plantetettleikane.

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Biennial bearing is a major problem for the Norwegian apple industry. Due to over-cropping one year where fruit size and quality are reduced, the trees are likely to turn into a pattern with high and low yield every second year. This inconsistent yield pattern provides problem for both the growers and the market. Commercial practise is to remove the excessive flowers or fruitlets by chemicals or by handthinning. The only officially registered agents for apple thinning are ethephon and ammoniumthiosulphat. The growers find them unpredictable in use and more knowledge is wanted in order to give more precisely thinning recommendations. Founded by the Norwegian Research Council and The Norwegian Industrial and Regional Developments Funds, a new project started at Ullensvang Research Centre in 2003. This project will focus on optimising the crop load and test different thinning agents under bloom and at different fruitlet stages on commercial important apple cultivars. Different crop levels will be established during and after bloom by hand adjusted by trunk cross sectional area. The experimental trees will be monitored during a 3-year period. Traditional pomological observations will be registered included storage of the fruits where fruit quality will be measured. In addition the response of leaf net photosynthesis to increasing irradiance levels to determine the photosynthetic light saturation using an infrared gas analyser will be registered. Leaf areas per tree will be calculated using an area meter. Percent tree light interception in mid-season will be calculated of above-canopy incident irradiance and of light transmissions measured in a defined grid pattern below the canopy using a lightmeter. In addition different thinning chemicals will be tested according the program to the working group of European Fruit Research Institute Networks. Emphasis will be put on concentration and thinning periods of the agents ethephon, ammoniumthiosulphat and compounds that could be approved for organic growing like colza oil. Similar observations will be recorded like in the crop load study.

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I eit tre-årig prosjekt vart det gjennomført ei teknisk vidareutvikling av sjølve konstruksjonen av dekkesystemet med vekt på forsterking av endetraversar og endestolpar. Teikningar er utarbeidde. Dessutan har det vorte arbeidd med biologisk utprøving med plastdekking som alternativ til sprøyting med soppmiddel mot rotning av søtkirsebæra. Plastdekket kan med fordel nyttast over lengre tid i sesongen enn i dag. Prosjektet var brukarstyrt

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Presentasjonane på den internasjonale hagebruksforskingskongressen i Toronto viste at mange arbeider for å redusera bruken av kjemiske plantevernmiddel i fruktomsetninga. Dette har auka interessa for "naturlege" stoff sine verknader på kvalitetstap og svinn under omsetning. Mange har stor tiltru til at 1-MCP skal revolusjonera "postharvest" arbeidet. 1-MCP blokkerer for verknaden av etylen. Andre aktuelle stoff er planteoljer og "naturlege" ekstrakt. Ved sida av kjøling og lagring i tradisjonell kontrollert atmonsfære (CA) (lågt oksygen og auka CO2-nivå), vart det vist resultat frå lagring i 100% oksygen. Andre aktuelle metodar som aukar lagringsevna er t.d. dupping i calsiumoppløysingar eller varmt vatn.

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Resultat frå forsøk med ulike dekkesystem for søtkirsebær sin effekt på mikroklima og fruktkvalitet er skildra i ein vitskapleg artikkel på engelsk. Resultata er delvis publisert på norsk i følgjande artikkel: Børve, J., A. Stensvand & M. Meland, 1997. Verknad av plastdekking på rotning hjå søtkirsebær. Informasjonsmøte i plantevern 1997 Grønn forskning 2/97. 252-255.

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Det er sjeldan her i landet at deler av eplekarten vert så sterkt oppvarma av sola at det vert sviskade på skinnet. I avgrensa omfang vart det registert på einskilde eplekart i juli i Ullensvang. Sjølve skaden arter seg som flekker på skinnet med fargeendringar som går frå kvit til meir solbrunt. Ved alvorleg skade vert skinnet mørkebrunt med utvikling av daudt vev under. Slike eple er verdilause som sal til frisk-konsum, men kan nyttast til saftproduksjon.

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Vekselbering i eple- årsaker og tiltak" er tittelen på eit nytt prosjekt som startar opp i 2003. Dette tre-årige prosjektet har som mål å etablera ein berekraftig produksjon med årlege, jamne avlingar av eple med høg fruktkvalitet. Ved hjelp av små- og storskalaforsøk med avlingsregulering av ulike eplesortar poda på ulike grunnstammer, skal kunnskapen implementerast til epledyrkarane.

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Årleg turrstoffproduksjon vart estimert frå åtte år gamle epletre med sortane "Fuji", "Royal Gala" og "Braeburn" poda på grunnstamma M9 og forma som slank spindel. Både frisk- og turrstoffproduksjon auka liniært med mengda av ljos som vart oppfanga i trea. Denne samanhengen tilsvarar ei avling på 16.9 tonn pr. daa med ei ljosoppfanging på 90 %. Energien som vart omdanna frå ljos i vekstsesongen til turrstoff i New Zealand var tilsvarande som i England. Skilnaden mellom desse to landa er at New Zealand har ein lengre vekstsesong og høgare innstråling. Turrstoffproduksjonen var fordelt til frukt, treaktig vev og blad med ei fordeling til frukt på 74, 72 og 63% for dei tre sortane "Braeburn", "Fuji" og "Royal Gala".

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Eplesorten "Discovery" poda på 8 grunnstammervart prøvde i intensive plantesystem i fem år ved to lokalitetar. Grunnstammene var to seleksjonar av M.9 (EMLA, RN.29), to frå den Polske (P) serien (P.59, P.60), tre frå Geneva (G) serien (G.30, G.78730-026, G.202) and M.26. Tre-storleiken var signifikant påverka av grunnstammene. P.59, G.78730-026 og M.9 RN.29 gav dei minste og G.30 og G.202 dei største trea målt som stammetverrmål. Avlinga var størst på P.59 og G.30 fylgd av G.202, P.60 and M.9 EMLA. Effektiviteten var største hjå tre av P.59 og dei to M.9 klonane. Det var liten skilnad på fruktvektene. Fruktkvaliten var generelt høg og det var liten skilnad mellom dei ulike grunnstammene.

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Tynning av dei viktigaste fruktsortane våre er eit absolutt krav for å sikra jamne avlingar og god kvalitet på frukta. Handtynning åleine er arbeidskrevjande og kostbart. Vanleg dyrkingspraksis er difor å nytta eit kjemisk tynningsmiddel først og så deretter justera for hand. For tida er berre Cerone og Ammoniumthiosulfat (ATS) godkjende som tynningsmiddel i eple og plomme og i tillegg svovelkalk i plomme. I forsøk dei siste åra har ATS gjeve god tynningsverknad i både eple og plomme. Middelet vert sprøytt ut når frukttrea står i full blom. Truleg verkar stoffet fysisk med sviing av dei blomane som allereie ikkje er pollinerte. For å få meir røynsle med dette stoffet, vart det i 2000 gjennomført storskalaforsøk hjå dyrkarar i Sogn og Fjordane med finansiering frå FMLA Sogn og Fjordane. Sprøyting under blomstringa med ATS og svovelkalk gav tilfredstillande tynningseffekt til plommesortane "Opal" og "Victoria". Tilsvarande bruk med ATS til eplesortane "Kronprins", "Summerred" og "Aroma" heva kvaliteten og reduserte avlinga noko, men auka blomemengda på trea året etter.

Sammendrag

I perioden 1998-2000 vart det gjennomført tynningsforsøk med plommesortane "Opal" og Victoria ved PlanteforskUllensvang og hjå dyrkarar. I 1998 vart utynna og handtynna "Victoria" tre samanlikna med kjemisk tynning ved full blom med 1% Armothin, 1,5 % ammoniumthiosulfat (ATS) og ei blanding med 10 ppm 1-naphylacetic acid (NAA) og 75 ppm etefon ein månad etter full blom. Same programmet vart gjennomført dei to fylgjande åra, men inkludert ei handsaming med 250 ppm etefon ved full blom i tillegg. Hjå dyrkarane vart det gjennomført 3 feltforsøk i år 2000 med sortane "Opal" og "Victoria" og tynningssprøytt med 1-1,5 % ATS og 5-7 % svovelkalk ved full blom i tillegg til ubehandla tre og handtynna tre. Alle tynningshandsamingane redusert avlinga og heva fruktkvaliteten (fruktstorleik, sukkerinnhald, fastleik og farge).

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Vanleg praksis ved etablering av eit intensivt fruktfelt er å planta trea på ei vegetasjonsfri stripe. Denne stripa vert halden vegetasjonsfri gjennom omløpet og hindrar konkurranse med andre planteslag om vatn og næring. Kjemisk reinhald har til no vore det rimelegaste og enklaste å gjennomføra. Denne artikkelen gjer greie for forsøk med kompost som jordforbetrings- og dekkemateriale i planteradene hjå epletre i to vekstsesongar. Ulike mengder med fersk kompost (5, 10 og 15 cm tjukt dekke saman med ubehandla) vart lagt ut i fruktrerekkja til eplesorten "Gravenstein" i 1999. Registreringane gjekk over to feltsesongar. Eit dekke med 10 cm fersk kompost i frukttrerekkja hemma oppspiring av frøugras i ein vekstsesong. Komposten frigav lite av dei lettløyseleg minerala kalium, fosfor, magnesium og kalsium til jorda første vekstsesongen. Men nitrogenet vart frigjort og teke opp i trea proporsjonalt med mengda av kompost tilført. Ny tilføring av kompost andre året førte til markert auke i jordreaksjonen og dei lettløyselege næringsemna i jorda, men ikkje til auka opptak i plantene. Tilføring av ulike mengder med kompost hadde liten innverknad på avling eller fruktkvalitet.

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Kompost frå våtorganisk avfall omdanna i reaktor har vorte prøvd i ulike mengder og mogningsgrader i feltforsøk og som vekstmedium til karplanter i åra 1999 og 2000. Fersk kompost i trerekkjene  nytta som dekkemiddel i frukthagar var spirehemmande på  frøugraset første året. Nitrogen vart frigjort og teke opp av trea. Mogen kompost som tilskot i jorda ved planting av prydtre og innblanding ved etablering av plen hadde positiv verknad på tilveksten. Innblanding av 7,5 og 15 tonn pr. daa med fersk og mogen kompost i jorda hemma  ikkje oppspiringa av gras. Særleg fersk kompost  i  mengdetilhøve 25 og 50 % i blanding med veksttorv hemma tilveksten sterkt av både plommetre, jordbærplanter og blåkorg  i karforsøk. Den negative verknaden av kompost i vekstmedia kan rettast opp med gjødsling og bruk av mogen kompost.

Sammendrag

An intensive field planting of `Edda", "Opal" and "Mallard" plum trees (Prunus domestica L.) all grafted on the semidwarf rootstock St. Julien A was established in 1993 at Ullensvang Research Centre, western Norway at 60 ° North. The objectives were to evaluate four different single row planting systems (vertical axis, free spindle, hedgerow and Y-trellis) and three planting densities ( 0.5, 1.0, 1.5 x 4 m for the Y-trellis and hedge trees and 2.0 x 4 m for the central leader trees) in a northern climate. These planting distances give a range of tree density of 1250 - 5000 trees per ha. The experiment gave a small yield in the third leaf on all canopy systems. During the first four cropping years, the yields/ha were positively correlated with tree density. Cumulative yield per hectare was highest on the Y-trellis and hedge trees with the highest density (5000 trees per ha). In the fourth leaf, the Y-trellis trees gave 15 tons per hectare. No differences in fruit size or the soluble solids content among canopies or densities were found.

Sammendrag

The cherry cultivars "Van", "Ulster" and "Burlat" grafted on the rootstocks seedling, `Colt" and `Gisela 5" were evaluated for important fruit quality parameters at Ullensvang Research Centre during the 1998 season. The largest fruit size was found on the cultivar/rootstock combinations `Van"/seedling, `Ulster/Colt" and `Burlat/Gisela 5". Other parameters like fruit firmness, stone weight, soluble solids, titratable acids and pH of the fruit juice were registered as well.

Sammendrag

Denne artikkelen gjer greie for eit forsøk med fire ulike kruneformer (hekk, Y-forma, akse-forma og fri spindel) og ulike planteavstandar til tre handelssortar (Edda, Opal og Mallard) ved Planteforsk Ullensvang. Dei fem første avlingsåra auka avlinga med plantetettleiken. Akkumulert avling var høgast for dei hekk- og Y-forma trea. Det var små skilnader mellom i fruktkvalitet mellom dei ulike sortane, kruneformene og plantetettleikane. Tidsregistreringane viste heller liten forskjell mellom dei ulike arbeidsoperasjonane og treformene.

Sammendrag

Apple fruit quality, particularly size, is known to be influenced by crop load; mean fruit weight declines as crop load increases.  Far less is known, however, on the influence of the number of  fruit on an individual fruit spur on the resulting fruit quality. In early November 2000 eight groups of eight multi-fruited spurs were selected on five trees of two cultivars, Royal Gala and Braeburn.  Each group of eight spurs consisted of four terminal and four two-year-old spurs.  Within each spur type, fruitlets were thinned to a) one king, b) one king and one lateral, c) one lateral or d) two lateral fruitlets.  Initial fruit diameters were recorded a few days later.  Fruit were strip picked in the middle of the normal harvesting period for each cultivar.  Statistical analysis at harvest was restricted to spurs which had maintained their original complement of fruit, as in some cases doubles were only singles at harvest.  Initial fruit size was a poor indicator of final fruit size.  Final fruit weight was not significantly altered by having one or two fruit on a spur.  The percentage blush was slightly reduced on the pairs with Royal Gala but not with Braeburn.  Effects on fruit maturity (BGC, SPI, firmness, soluble solids) were non-significant. Fruit on terminal spurs were larger than on lateral spurs with both cultivars. Fruit maturity, however, tended to be more advanced on lateral spurs, particularly with Royal Gala.

Sammendrag

Eit dyrkingsproblem er at søtkirsebær-trea utan synlege sjukdomsteikn brått kan stagnera i vekst og døy endå om feltet har fått optimalt stell. For tida er det ingen konkrete rådgjerder for dyrkarane bortsett frå å planta nye tre i staden for dei som gjekk ut. Med finansiering frå Statens Landbruksbank har Planteforsk Ullensvang i samarbeid med Planteforsk Plantevernet gjennomført det eitt-årige prosjektet "Kartlegging av årsaker til tredaude i søtkirsebær" i 1999. Kartleggingsarbeidet var delt i to: 1.Kartlegging av 5 bruk som har problem med tredaude blant medlemene til Hardanger Frukt og Bær med utttak og analyse av nematode-, sopp-, virus- og jord- og bladprøvar saman med feltinspeksjonar. 2. Spørjeundersøking til søtkirsebærdyrkarar ved 5 fruktlager i Ullensvang om tilhøve som kan tenkjast å påverka tredaude i søtkirsebær . Grupper av rotnematodar som gjer skade på frukttrea var registrert i alle hagane og kan såleis vera medverkande til symptoma. Det var også mogeleg å relatera høge populajonar av rotsårnematodar til dårleg tilvekst og høge spiralnematodetal til tidlegare observasjonar av tredaude. Det vart ikkje påvist at ulike insekt, soppar, bakteriar eller virus var primærårsak til denne tredauden. Spørjeundersøkinga viste at mange søtkirsebærdyrkarar meinte det var skilnad mellom kor utsette ulike sortar og grunnstammer var for tredauding i frukthagane. Gjenplanting på same arealet kort tid etter at det var rydda steinfruktplanting fremja tredauding. Lauvtrebarkbillen var årsak til tredaude, men då er diagnosen oftast enkel å stilla.

Sammendrag

Denne artikkelen omtalar det 4-årige prosjektet "Tredaude i søtkirsebær (Prunus avium L.) - årsaker og tiltak" finansiert av SND og NFR. I prosjektet skal det: - Studera vekst og utvikling i søtkirsebærtre med ulike kombinasjonar av sort, grunnstamme og skjeringsmetodar dyrka på ulik kulturjord . - Dokumentera verknaden av avlingsregulering (tynning) på vekst og utvikling. - Undersøkja vatn- og næringsstofftransporten gjennom ledningsbanane i podeom-rådet av ulike kombinasjonar av grunnstammer og sortar. - Studera utbreiing av phytoplasma (vegglause bakteriar) i søtkirsebærtre Feltarbeidet skal gjennomførast ved Planteforsk Ullensvang og hjå søtkirsebærdyrkarar i Hardanger og Sogn.

Sammendrag

Eit dyrkingsproblem er at søtkirsebær-trea utan synlege sjukdomsteikn brått kan stagnera i vekst og døy endå om feltet har fått optimalt stell. For tida er det ingen konkrete rådgjerder for dyrkarane bortsett frå å planta nye tre i staden for dei som gjekk ut. Med finansiering frå Statens Landbruksbank har Planteforsk Ullensvang i samarbeid med Planteforsk Plantevernet gjennomført det eitt-årige prosjektet "Kartlegging av årsaker til tredaude i søtkirsebær" i 1999. Dette var eit oppdrag for Hardanger Frukt og Bær. Kartleggingsarbeidet var delt i to: 1. Kartlegging av 5 bruk som har problem med tredaude blant medlemene til Hardanger Frukt og Bær med utttak og analyse av nematode-, sopp-, virus- og jord- og bladprøvar saman med feltinspeksjonar. 2. Spørjeundersøking til søtkirsebærdyrkarar ved 5 fruktlager i Ullensvang om tilhøve som kan tenkjast å påverka tredaude i søtkirsebær . I desse fem søtkirsebærhagane, var næringstilstanden av makronæringsemne i jorda høg og delvis over det optimale. Ubalanse mellom næringsemna kan vera med og svekka trehelsa til trea. Grupper av rotnematodar som gjer skade på frukttrea var registrert i alle hagane og kan såleis vera medverkande til symptoma. Det var også mogeleg å relatera høge populajonar av rotsårnematodar til dårleg tilvekst og høge spiralnematodetal til tidlegare observasjonar av tredaude. Det vart ikkje påvist at ulike insekt, soppar, bakteriar eller virus var primærårsak til denne tredauden. Grundigare undersøkingar og då særleg av nematodar i jorda bør utførast vidare for å påvisa årsaker til denne tredauden i søtkirsebær og finna mogelege rådgjerder for å bekjempa dei ulike potensielle skadegjerarane.  Spørjeundersøkinga viste at mange søtkirsebærdyrkarar meinte det var skilnad mellom kor utsette ulike sortar og grunnstammer var for tredauding i frukthagane. Gjenplanting på same arealet kort tid etter at det var rydda steinfruktplanting fremja tredauding. Lauvtrebarkbillen var årsak til tredaude, men då er diagnosen oftast enkel å stilla. Kulturmåten som gjødslings- og vatningspraksis verkar mindre inn, men vass-sig på trerøtene var negativt.

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nne rapporten omhandlar resultat frå det 2-årige prosjektet "Dekkesystem i morellplantingar for å verna fruktene mot skade av regn". Prosjektperioden var frå 1.1.97 til 31.12.98. Hovudmålet var å utvikla vindstabile, bruksvenlege og kostnadsgunstige dekkesystem for å sikra god kvalitet og årssikre avlingar og dermed lønsam produksjon av søtkirsebær. Prosjektet vart finansiert av Statens Landbruksbank og Norfolier a/s & co og gjennomført av Planteforsk Ullensvang.  Ei rekkje plastdukar, ulike kombinasjonar av festeinnretningar, elastiske stropper og festekrokar til eit tre-strengs dekkesystem for søtkirsebærplantingar vart utprøvd som laboratorieprøvar ved Teknologisk Institutt, hjå Knut Skjervheim, Agroprosjekt og i felt hjå to fruktdyrkarar i Hardanger sesongane 1997 og 1998. Ei bygge- og bruksrettleiing for dekkesystem i søtkirsebærplantingar vart utarbeidd på grunnlag av dei oppnådde resultata.

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Den amerikanske tidlegeplesorten "Geneva Early" kjem tidleg i bering, er bra produktiv og ber årvisst. Sorten mognar inntil ei veke før "Quinte", og fruktkvalitet og haldbarheit er bra for ein sort med så tidleg mogning. "Geneva Early" er svært utsett for mjøldogg og nokså utsett for skurv. Sorten kan sjå ut til å høva best under Austlandstilhøve, der fruktfarge og smak vert betre, og problemet med mjøldogg er mindre.

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Artikkelen gjev ei omtale av forskingsarbeidet innan plantesystem til frukttre utført ved Ullensvang Forsøksgard gjennom 50 år 1949-1999.