Biografi

Mitt hovudarbeidsområde er sjukdomar relatert til fruktdyrking. Forskarkarrieren min starta med ei doktorgrad om rotne moreller. Etter det har eg hatt fokus både på rotne eple, plommer og moreller i tillegg til viktige sjukdomar på trea som frukttrekreft og bakteriekreft. Forskinga har vore anvendt og med fokus på problemstillingar som er viktige for heile verdikjeda i fruktnæringa. Delar av arbeidet vert difor gjort i nært samarbeid med pakkeri og planteskular.

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Det er utført forsøk med soppmidler i bygg, løk, gulrot og eple. I bygg er det testet ulike varslingsmodeller i VIPS mot byggbrunflekk. I løk er det testet ulike beisemidler for å forebygge soppsjukdommer og sikre god løkkvalitet fra starten. I gulrot er det utført forsøk mot gropflekk og ulike lager- og bladflekksjukdommer både i felt og på lager. I eple er det gjort forsøk for å finne nye midler mot lagersjukdommer.

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Bacterial canker, caused by Pseudomonas syringae pv. syringae and pv. morsprunorum, is one of the most important diseases of stone fruit trees (Prunus spp.). The pathogen infects buds, flowers, fruitlets, leaves and shoots, from which the disease spreads to the branches, boughs and trunks, causing necrosis and cankers. The efficacy of different chemical and biological products for the control of bacterial canker on stone fruit trees was tested in 2018–2021. The experiments were conducted in sour cherry, plum and sweet cherry orchards in central Poland. Foliar application of the tested preparations was performed three times a season. The biological efficacy of the tested products in the control of bacterial canker was evaluated on sour cherry on the basis of infected leaves and fruits and on plum and sweet cherry on the basis of infected leaves. The highest efficacy was observed for products containing various forms of copper—copper oxide, copper oxychloride and copper hydroxide—as well as fertilizers with copper gluconate and the fungicide Luna Care 71.6 WG (fluopyram and fosetyl-Al). However, the biological preparations were significantly less effective. The conducted studies showed that preparations based on copper gluconate can be a valuable alternative to typical copper fungicides.

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The combination of preharvest treatments with calcium chloride and fungicides, and storage of maturity graded fruit were assessed in five European plum cultivars. At harvest, samples of fruit within a commercially suitable range in ripening were divided into two categories: less-ripe (tree ripe-) and more-ripe (tree ripe+). The fruit were stored for 10–14 days at 4 °C followed by 2–3 days at 20 °C before the assessment of fungal decay. If calcium chloride was applied six times each season, postharvest fruit decay was significantly reduced in four of nine experiments, with a total mean reduction of around 50%. Two calcium applications in combination with a fungicide treatment reduced decay by approx. 60% compared to the untreated in one experiment. In six of seven experiments there was no effect of preharvest fungicide applications. In six of 10 experiments, fruit of the category tree ripe- had fewer fruit with fungal decay after storage than the tree ripe+fruit. The higher incidence in the category tree ripe+fruit was primarily due to brown rot, Mucor rot, and blue mould. For the category tree ripe+, there was two to ten times more decay than on tree ripe- fruit after a simulated shelf-life period. To ensure low incidence of fungal decay, fruit of commercial harvest maturity may thus be separated in two ripening categories, one for rapid distribution to the market (tree ripe+) and another for extended distribution time (tree ripe-).

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Key words: VKM, pest risk analysis, Norwegian Scientific Committee for Food and Environment, Norwegian Food Safety Authority, Sudden oak death, Phytophthora ramorum Introduction The Norwegian Food Safety Authority has asked the Norwegian Scientific Committee for Food and Environment for an updated pest risk assessment of Phytophthora ramorum in Norway. The previous risk assessment of P. ramorum for Norway is from 2009. Since then, the pathogen has been detected repeatedly in Norway, primarily in parks, garden centres, and nurseries in southwestern Norway. The knowledge base concerning P. ramorum has changed since the last pest risk assessment, with increased genetic knowledge about different populations, lineages, and mating types. The risks associated with P. ramorum have also changed, since the disease has become epidemic in new host plants, such as larch trees in England. This updated pest risk assessment will provide important input to the Norwegian Food Safety Authority’s efforts to develop the Norwegian plant health regulation. Methods VKM established a project group with expertise in plant health, forest pathology, horticultural plant pathology, plant disease modelling, and pest risk assessment. The group conducted systematic literature searches and scrutinized the relevant literature. In the absence of Norwegian studies, VKM relied on literature from other countries. The group did a quantitative risk assessment describing the level of confidence in the conclusions and identifying uncertainties and data gaps. The report underwent pre-submission commenting and external expert reviewing before final approval and publication. Results and conclusions Phytophthora ramorum is present in the PRA area but has a restricted distribution, mainly being detected in the southern and southwestern parts of Norway. The only P. ramorum lineage considered to be present in Norway is EU1 with mating type A1. The other lineage in Europe, EU2, has so far mainly been documented from the UK. The most widely distributed multilocus genotype of P. ramorum in Norway is EU1MLG1, which became dominant in Europe (including Norway) after 2008. In North America, the NA1, NA2, and EU1 lineages are known from both nurseries and forests. NA1 and NA2 are of the opposite mating type (A2) than European lineages. Recently, various other lineages of P. ramorum have been described from Asia. The main risks for future problems with P. ramorum in Norway are related to entry and establishment of non-European isolates (of all lineages), as well as emergence of new genotypes in European P. ramorum populations. There are several options for diagnosing P. ramorum to species and lineage (mainly EU1, EU2, NA1, and NA2). From a management perspective it is more important to distinguish these entities than mating type and isolate groups (genotypes). The latter are mainly relevant for research purposes or in cases of unexpected disease developments, such as new hosts, increased spread or more severe symptoms on known hosts. However, for more detailed regulation, monitoring, and management of P. ramorum it could also be useful to test for genotypes, i.e. to distinguish EU1MLG1 from other genotypes. Rhododendron remains the most important host plant for P. ramorum in Norway, both in terms of imported plants and detections (mainly in nurseries, garden centres, and public parks). Species in other ornamental plant genera, such as Viburnum, Pieris, and Kalmia, are also listed as major hosts in Europe, and P. ramorum has been detected at least once on species in all these genera in Norway. In the US, Rhododendron, Viburnum, Pieris, Syringa, and Camellia are considered to be the main ornamental hosts. .....................

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Skadedyr: I 2021 er det utført forsøk med skadedyrmidler i eple, pære, plomme, prydrogn og jordbær. Her er det testet ulike midler mot blodlus, teger, plommevikler, rognebærmøll og bladlus. I tillegg er det utført forsøk for å vurdere om feromon-forvirring kan brukes som planteverntiltak mot viklere i eple. Det er også undersøkt forekomst av sviskade på epleblad etter bruk av vegetabilsk olje. Sjukdommer: Det er utført forsøk med soppmidler i bygg, løk, gulrot og eple. I bygg er det testet ulike varslingsmodeller i VIPS mot byggbrunflekk. I løk er det testet ulike beisemidler. I gulrot er det utført forsøk mot gropflekk og mot ulike lager- og bladflekksjukdommer. I eple er det gjort forsøk for å finne nye midler mot lagersjukdommer.

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Det ble i 2020 utført forsøk mot soppsjukdommer i grønnsaker, potet, plomme, bringebær og korn. I potet ble det gjort forsøk mot tørråte, i plomme mot plommepung og i bringebær mot rust. I korn ble det testet nye sprøytestrategier mot bladflekksjukdommer i bygg og vårhvete, og i grønnsaker ble det gjort forsøk mot lagringssjukdommer i gulrot og løk. Det er utført et forsøk med biologiske og kjemiske skadedyrmidler mot kålmøll i kinakål og et forsøk med pluggbehandling av kålplanter (hodekål) før utplanting for beskyttelse mot kålflueangrep. Det er også utført forsøk med kjemiske middel mot bringebærbille i bringebær, kirsebærmøll i kirsebær og mot plommevikler i plomme. I tillegg har NIBIO utført forsøk for å vurdere om feromonforvirring kan brukes som planteverntiltak mot eplevikler og sju andre viklerarter i økologisk epleproduksjon.

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Secured supply of apple fruit for industrial use, especially for production of cider was investigated. The research questions were; is it more land to be used for apple growing in the Hardanger region?, is it possible to develop an own growing concept for fruit for industrial use?, how is the economy in an own concept? And what quality demands for the raw material is needed? More land is available in the region and how much is dependent on which quality the producers demand. The input factors in a growing concept were evaluated for economically impact and price level for the different classes were the most important. Fruit of different origin (discarded at picking or at grading) were compared. Yield level was most likely the most important factor for the differences found. Prognose of amount available for industry was calculated based on models from other countries and found to have potential. Knowledge gaps were identified, and further work is needed to determine quality demands.

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Silverleaf is an important fungal trunk disease of fruit crops, such as Japanese plum (Prunus salicina). It is known that infection by Chondrostereum purpureum results in discolored wood, “silvered” foliage, and tree decline. However, effects on fruit yield and quality have not been assessed. Therefore, the objectives of this study were to determine C. purpureum pathogenicity on P. salicina and the effects on physiology, fruit yield, and quality, in Chile, in 2019 and 2020. Wood samples from affected plum trees were collected in the Chilean plum productive area. Fungi were isolated by plating wood sections from the necrosis margin on culture media. Morphological and molecular characteristics of the isolates corresponded to C. purpureum (98%). Representative isolates were inoculated from healthy plum plants and after 65-d incubation, wood necrotic lesions and silver leaves were visible. Fungi were reisolated, fulfilling Koch’s postulates. To determine Silverleaf effects, xylem water potential and fruit yield and quality were measured in healthy and Silverleaf-diseased plum trees ‘Angeleno’. Water potential was altered in diseased trees, and fruit yield was reduced by 51% (2019) and by 41% (2020) compared to fruit from healthy trees. Moreover, cover-colour, equatorial-diameter, and weight were reduced, and fruit were softer, failing to meet the criteria to be properly commercialized and exported to demanding markets.

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Denne rapporten presenterer resultatene fra prosjektet «Valuation of the Norwegian plant health regime from an environmental, economic and social perspective (PlantValue)», som ble finansiert av Forskningsrådet gjennom en utlysning i samarbeid med Mattilsynet om midler til forvaltningsforskning på dyre- og plantehelse. Formålet med prosjektet var å få økt kunnskap om de miljømessige, økonomiske og sosiale konsekvensene av reguleringen av plantehelse i Norge og ulike metoder for å måle og utforske disse. Vi valgte å fokusere på et utvalg ulike former for reguleringer, og gjennom utvalgte casestudier har vi sett på betydningen av reguleringene for mattrygghet, helse, miljø, produsentøkonomi og forbrukervelferd.....

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The major part of Norwegian apples is marketed within 3-4 months after harvest. ‘Summerred’ is a popular medium early cultivar in Norway, however, it is known to soften quickly during storage and marketing. Storing apples in low temperature and low oxygen atmosphere will slow down the ripening and the fruit will keep green and firm. Delayed cooling has been reported to reduce susceptibility to develop physiological disorders like scald. The experiment included different strategies in delaying cooling (5 days at 7°C) and allowing the apples to reach 1 kPa oxygen storage after an intermediate period (5 days) at 3 kPa oxygen. The main focus was on changes in firmness, degreening, scald and fruit rots. The apples were stored for 3, 6 or 9 weeks in 1 or 4°C and analyzed for standard fruit quality factors (color, firmness, IAD-index, starch, soluble solids content and titratable acidity) as the samples were removed from low temperature and low oxygen storage and after a week at 20°C in regular atmosphere (shelf life). Physiological disorders and fruit rots were registered. In these experiments the fruit quality changes were greater (poorer quality) in apples kept at 7°C for 5 days before storage at 1 or 4°C compared to apples stored immediately at low temperature. The intermediate storage in 3 kPa oxygen tended to make the apples keep firmer during storage. The stepwise reduction in oxygen content reduced the negative effect of delayed cooling. Delayed cooling slowed the starch degradation. The incidences of soft scald and fruit rots were low, and the effects of delayed cooling and/or delayed low oxygen storage were weak.

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Infections of Neonectria ditissima, the cause of European fruit tree canker, may be initiated during propagation. In a survey of 19 commercial apple orchards in southern Norway in the year of planting or the following year, the graft-union area of 15,270 trees was examined. The disease was found in 53% of the orchards, at a low incidence (<10%) with two exceptions (13 and 42%). Scion wood from mother trees with no, a few or several cankers were used to propagate trees that were surveyed for up to 38 months. In total 20 out of 1116 (1.8%) trees developed canker. The higher the number of cankers was on the mother trees, the higher was the number of trees developing canker after grafting. Infections developed on both cultivars (Discovery, Summerred) and all three rootstocks (Antonovka, B9, M9), but more so on grafted than T-budded trees, and more in 2015 than in 2014. When the scion wood was inoculated at the time of T-budding or grafting, disease development went faster and to a higher incidence on T-budded (94%) than on grafted trees (50%). Dipping the scion wood end in a spore suspension prior to grafting resulted in more infections than when a suspension droplet was placed on the bud and bark surface of the scion wood after grafting. The present investigation documents that scion wood may harbour inoculum of N. ditissima. Furthermore, infections may be initiated at time of propagation, and management practices of both scion wood production and nurseries should encounter that fact.

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Sweet cherry fruit delivered at three packinghouses over two years in southern Norway was assessed for postharvest fungal decay after being graded in a line with water containing 2 ppm chlorine, in comparison with non-graded fruit. Assessment of decay was carried out after cold storage of the fruit for ten days at 2°C, followed by two days at 20°C. In mean of all assessments, there was no difference in total decay after storage between fruit graded in a water line or non-graded fruit, however, the first year there was a higher total incidence of fruit decay on water-graded fruit after storage. The grading-water was not changed during the day, but time of grading during the day did not seem to influence the amount of decay. Mucor rot and grey mould accounted for 80 and 19%, respectively, of the decay averaged for all assessments, and there was no significant difference in decay of the two diseases if graded in water or not. For blue mould and brown rot, the incidence was lower in water graded fruit, while it was the opposite for Cladosporium rot. On average, fruit decaying fungi developed on PDA from 57 and 17% of water samples from grading lines in the two years, respectively. On pieces with filter paper wetted in different locations of the grading line, 87% contained fruit decaying fungi when placed on PDA, and Mucor sp. was the most prevalent pathogen. Fruit cooled in a hydro-cooler containing either 2, 10 or 50 ppm chlorine, all reduced decay with about 75% compared to non-chlorinated water. Although the grading water may contain spores of pathogenic fungi, the present results indicated that water containing 2 ppm chlorine does not significantly increase fruit decay. Thus, only a slight chlorination of grading water may be sufficient to reduce postharvest contamination.

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The positive effect of low oxygen and high CO2 for sweet cherry (Prunus avium L.) storability is well-known. In the present experiment, a combination of controlled atmosphere (CA; 2°C, 5% O2 and 15% CO2) storage and modified atmosphere in consumer packaging (MAP) were assessed. Fruit of 'Kordia' were packaged directly (0-week CA) or after three weeks in CA storage (3-week CA). The different packages were 1: macro-perforated polyethylene bag (carry bags); 2: trays wrapped in perforated films giving passive modified atmosphere with high CO2 concentration (MAP-high CO2); 3: similar as 2, but with low CO2 concentration (MAP-low CO2); 4: perforated shaker with lid containing cherries with stem; and 5: similar as 4, but with fruit without stems. The consumer packages were stored at 4°C for 5 days and thereafter for 3 days at 4°C (Chill) or 20°C (Retail) simulating different retail storage conditions. The weight loss was below 1% for fruit in all packages stored at chill conditions. At retail conditions, weight loss for cherries in carry bags varied between 2.2 and 8.4%, whereas MA packages had insignificant weight loss. Fungal fruit decay was below 0.5% for 0-week CA cherries stored at chill conditions for 8 days, and from 7 to 14% for 3-week CA cherries stored at chill conditions for 6 days after packaging. At retail conditions, 25 to 52% decay was detected at end of storage period after previous storage in 0 and 3 weeks in CA, respectively. Sweet cherries of 'Kordia' did not maintain an acceptable quality in 3 weeks of CA with consecutive simulated distribution conditions during 6 days. Fungal decay was lower in carry bags and MA packaging with high CO2, and the MA packages had additionally insignificant weight loss in mean of the different temperature regimes and storage times.

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Modified atmosphere packaging (MAP) may inhibit undesirable quality changes of fruit and vegetables. The aim of this experiment was to evaluate the effect of MAP on selected quality parameters for sweet cherries (Prunus avium L.) stored at simulated distribution chain temperatures. ‘Lapins’ sweet cherries with maturity grade 4-5 and 6-7 were packaged in macroperforated polyethylene “carry bags” (control) and in trays wrapped in a laser perforated film giving passive modified atmosphere (MAP). After packaging, the cherries were stored at 4°C for 5 days and thereafter for 3 days at 4°C (chill) or 20°C (retail) simulating storage at chill or room temperature in the grocery stores. Headspace gas atmosphere in the MA packages, fruit quality, weight loss and amount of fungal fruit decay and other decays were recorded after 1, 5 and 8 days of storage. The gas atmosphere in MA packages was approximately 18% O2 and 4% CO2 at 4°C and between 6-9% O2 and 12-14% CO2 at 20°C. The weight loss was negligible in the MA packages at both storage conditions, whereas the cherries in carry bags showed a weight loss from 1 to 4%. The stem colour was significantly browner in the carry bags compared to the MA packages after 8 days of retail storage. Fungal decay was below 0.5% for both maturity grades stored at chill conditions for 8 days. At retail conditions, 4 and 6% decay was detected for maturity grade 4-5 in MA-packages and carry bags, respectively. For maturity grade 6- 7, the MA-packages had 9% decay and the carry bags 7%. The overall picture was that MA packaging for sweet cherries better maintained the fruit quality than the carry bags during the storage period of 8 days at two simulated retail conditions.

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Introduction and purpose: The ability of apple rootstocks to become infected by Neonectria ditissima, the cause of European canker, was studied over two years. Materials and methods: Rootstocks B9 and M9 with a size suitable for grafting (6-10 mm stem diameter, termed rootstocks), and smaller sized rootstocks (<5 mm stem diameter, termed transplants) of B9, M9, M26, MM106 and Antonovka were inoculated with N. ditissima at different times, either with contaminated map pins or with spore suspensions. In addition, the rootstocks were either defeathered (side shoots removed), topped (top shoot headed) or both, to create wounds that would normally occur during propagation, while wounds on transplants were made by removing leaves. Results and discussion: One month after inoculation, slightly sunken canker lesions had developed around the inoculation points of the map pins or wounds. No lesions developed on the non-inoculated controls. Map pin inoculation resulted in 30% to 89% infection and spore suspension sprayed on wounds from 5% to 45% infection. When the cankered areas were split open, brown lesions with necrotic tissue due to infection by N. ditissima appeared. The transplants of M9, M26 and MM106 inoculated with contaminated map pins in 2014 developed necrosis on 40% to 67% of the plants, but there were no differences in the incidence or severity among the different types. On the transplants of B9, Antonovka and M9 inoculated in 2015, there was more necrosis on B9 (42%) than on Antonovka (11%) and more sporulating lesions on B9 (29%) than on M9 (9%) or on Antonovka (4%). Conclusion: It can be concluded that rootstocks used for apple trees may become infected by N. ditissima, and wounds should thus be protected during propagation.

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Production of inoculum of Colletotrichum acutatum from both previously infected and overwintered tissue, as well as newly developed plant tissue of sour cherry (Prunus cerasus), was studied in southern Norway. Plant parts were sampled from commercial, private, or research orchards, and incubated for 2 to 14 days (time depended on tissue type) in saturated air at 20°C. In early spring, abundant sporulation was found on scales of overwintered buds and shoots. A mean of 35% infected buds in four cultivars was observed, with a maximum of 72% of the buds infected in one of the samples. Over 3 years, the seasonal production of overwintered fruit and peduncles of cv. Fanal infected the previous year was investigated. In all three years, the infected plant material was placed in the trees throughout the winter and the following growing season; in two of the years, fruit and peduncles were also placed on the ground in the autumn or the following spring. Old fruit and peduncles formed conidia throughout the season, with a peak in May and June. Spore numbers declined over the season, but the decline was more rapid for plant material on the ground than in the trees. On average over 2 years, 68.7, 24.0, or 7.3% of the inoculum came from fruit placed in the trees, placed on the ground in spring, or placed on the ground the preceding autumn, respectively. The number of fruit and peduncles attached to the trees in a planting of cv. Hardangerkirsebær was followed from February to July one year, and although there was a decline over time, fruit and/or their peduncles were still attached in substantial numbers in July, thus illustrating their potential as sources of inoculum. In observations over 2 years in a heavily infected orchard of cv. Stevnsbær, 75 and 47% of flowers and newly emerged fruit, respectively, were infected. Artificially inoculated flowers and fruit produced conidia until harvest, with a peak in mid-July. It may be concluded that previously infected and overwintered, as well as newly emerged tissue of sour cherry, may serve as sources of inoculum of C. acutatum throughout the growing season.

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Aroma is an important quality factor in fruit, and it is important to know the effect of new orchard management practices on fruit aroma. Fruit growers are using more foliar fertilizers to achieve the optimum mineral status in fruit. In this work the effects of adding extra nitrogen, calcium and both nitrogen and calcium to apple trees in the fruit cell division phase were studied. Even though the given nitrogen and calcium did not give significantly higher content of N and Ca in the treated fruits, differences in the contents of some aroma compounds were found. Nitrogen treated trees gave apples with more hexanal, a compound known in unripe ("green, grassy") apples. When both calcium and nitrogen were applied, the negative effect of nitrogen on aroma compounds was less pronounced. The aroma of these fruits was more similar to the controls. Using multivariate statistical analyses, the grouping of the different treatments during storage was confirmed. Foliar fertilization with nitrogen and calcium during the cell division phase had a significant effect on the amount of aroma compounds in apples at harvest and during storage.

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Fungi within the Colletotrichum acutatum species complex occur asymptomatically on plant parts of many different plant species. Leaves from apple orchards in southern Norway were sampled, frozen for five hours and incubated for six days to reveal presence of asymptomatic infections of C. acutatum. Number of leaves (incidence) and leaf area covered (severity) with conidial masses of C. acutatum were assessed biweekly on cv. Aroma from late May to late September during three growing seasons. The first finding of conidial masses occurred in the second half of July, and there was a higher incidence occurring in August and September. Sampling of leaves from fruit spurs and vegetative shoots of cvs. Aroma and Elstar showed that conidial masses of C. acutatum developed on leaves on both shoot types, and there was no difference in incidence between these two types. The fungus was detected on leaves from six of eight commercial orchards of cv. Aroma over three years, with a mean incidence of 5.5 %. After storage, bitter rot was found on apple fruit from all eight orchards. There was no correlation between incidence of conidial masses of C. acutatum on leaves and on fruit. In all orchards and seasons investigated, incidence and severity on leaves varied from 0 to 67%and 0 to 85 %, respectively. The discovery of apple leaves containing conidial masses of C. acutatum clearly indicate for leaves as a potential source of inoculum for fruit infections.

Sammendrag

Effects of controlled atmosphere (CA) conditions on physiological disorders and fungal fruit decay on apple ‘Aroma’ were investigated. Fruit from three growing seasons were stored at 1% or 2% O2 (both at 2% CO2) at either 1°C or 3°C in small research units; controls were kept in the same ventilated rooms at the two temperatures (ambient air). The fruit were removed from storage after four or six months and assessed for fruit decay immediately afterwards and after two weeks at 20°C. Fruit quality parameters were recorded at the end of storage. On a three-year average, fruit stored in CA was less ripe at the end of storage. After both four and six months storage, CA reduced total decay (physiological disorders and fungal decay) by on average 70% and 45%, respectively, compared to storage in ambient air. Senescent breakdown was lower after CA storage for four months, but not after six months and not after simulated shelf life. Soft scald was lower when stored in CA both after cold storage at 1°C and simulated shelf life. After storage at 3°C there was lower incidence of soft scald when stored in CA after four months, but not after six months. For fungal fruit decay in general, there was no effect of low oxygen, however, 2% O2 gave slightly less bitter rot (Colletotrichum acutatum) than 1% O2 and significantly less than ambient air after simulated shelf life. Averaged over all oxygen levels, 1°C gave significantly less bitter rot than 3°C. It may be concluded that use of CA for storage of ‘Aroma’ is a good way of reducing development of physiological disorders. However, development of bitter rot seemed to be more influenced by temperature and storage time than by low O2.

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Shelf life of plum is limited by several factors, including development of fungal decay. In either one or two seasons, European plum cultivars were exposed to different applications of calcium or fungicide before harvest or left unsprayed. On the experimental trees, the yield was harvested as commercial practice, giving a sample of fruit with a range in maturity acceptable for sale. The yield was divided into two groups, less and more ripened fruit. Fruit samples from each group were stored for 10-14 days at 4°C followed by a simulated shelf life period of 2-3 days at 20°C. Fruit quality was assessed at harvest and after storage. Number of fruit with fungal decay was counted at the end of storage and after simulated shelf life. At harvest, the more ripened fruit had higher weight, soluble solids content, background and cover colour, and lower firmness in most of the experiments. Fruit from trees sprayed six times with calcium had higher weight in first year, but not in second, was less ripen as measured by colour and firmness on some cultivars, but not on others. Time of fungicide application had no effect on fruit quality at harvest. Differences in fruit quality at harvest were most often similar after storage. Fruit grouped as more mature at harvest developed more fungal decay after simulated shelf life than less mature fruit in five of eight experiments. In one out of six experiments calcium applications reduced development of postharvest fungal decay. Fungicide applications had no effect on postharvest fungal decay in either of four experiments. The present results indicate that the ripening degree of plum fruit is more important for development of fungal decay than preharvest applications of calcium or fungicides

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At main commercial harvest four pallet sized boxes of apple (Malus ×domestica) cultivar ‘Aroma’ from one grower were assessed for maturity by using a portable spectrometer giving an IAD index (index of the absorption difference between 670 and 720 nm) indicating chlorophyll content. The apples were sorted into three groups; IAD index <0.65, 0.66 - 0.80 and >0.81. Apples of all groups were assessed for quality parameters at harvest and after storage in CA-bags at 2°C (about 100% RH) or natural atmosphere (NA) at 1°C (about 90% RH) for three months and after simulated shelf life at 20°C for 14 days. At the same times the apples were assessed for decay, both physiological disorders and fungal attacks. The CA-bags were gas-tight plastic bags for one pallet and were connected to an external gas control unit. The atmosphere inside the CA-bags consisted of 2% O2 and 2% CO2 during the cold period. At the start of the experiment apples from the different IAD index groups were not similar in subjectively judged ground colour and cover colour but similar in firmness and starch content. After three months of cold storage both apples stored at natural atmosphere and in CA-bags were still different in ground and cover colour and IAD index. In apples from CA-bags the titratable acidity content was higher in >0.81 group than on those with an IAD index <0.65. After 14 days at 20°C apples with IAD index >0.81 were different from <0.65 group in ground-colour and IAD index, but other parameters assessed were similar. After three months CA-bag stored apples had 2% visible decay but apples stored in NA had up to 27% decay. The apples with IAD index <0.65 had highest incidence of decay. After 14 days at 20°C apples with IAD index <0.65 stored in CA-bags had developed 5% decay while there was no decay in the other IAD index groups. Apples with IAD index <0.65 stored in NA had developed 45% decay after 14 days at 20°C while apples from the other groups had developed about 20% decay. Senescent decay and breakdown accounted for 90% of the physiological disorder while bitter rot was the major reason of fungal decay. CA-bags were found to be an efficient tool to prolong storage period and IAD index values might be useful in determining the potential storage life.

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The shelf life of plum fruit (Prunus domestica) is limited due to among other factors fungal fruit decay. Absorbent pads (“fruit pads”) are commercially used today in order to absorb juice from the berries and condense water and hence reduce fungal growth. The aim of this experiment was to evaluate the effect of different types of absorbent pads on weight loss, decay and quality for plum fruit under realistic storage conditions. Plum fruit (‘Reeves’ and ‘Jubileum’) were delivered at a commercial packing house, packed in trays on a flow packaging machine with three different types of absorbent pads placed at the bottom of the trays (standard fruit pad and two humidity control pads with different active compounds; denoted active pad 1 and 2). Trays without pads were controls. After packaging, plums were stored at 3 or 6°C for 7 days and thereafter 2 days at 20°C. Fruit quality, weight loss and amount of fungal decay were recorded at the end of the storage period. The different pads had no significant effects on ripeness state measured by DA-meter and fruit firmness measured at end of storage. The pads had significantly different effect on weight loss, and for ‘Jubileum’ the weight loss was 1.5% for the active pad 1, 2.5% for the active pad 2 and below 1% for the standard pad and the control. Significant effects were found for cultivar and absorbent pads on the total amount of decayed fruit. ‘Jubileum’ was more vulnerable to decay than ‘Reeves’, and the active pad 2 had the lowest number of decayed ‘Jubileum’ fruit stored at 3°C. More work and a cost-benefit analysis should be performed before absorbent pads are recommended for plum fruit.

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Sammendrag

The shelf life of plum fruit (Prunus domestica) is limited due to among other factors fungal fruit decay. Absorbent pads (“fruit pads”) are commercially used today in order to absorb juice from the berries and condense water and hence reduce fungal growth. The aim of this experiment was to evaluate the effect of different types of absorbent pads on weight loss, decay and quality for plum fruit under realistic storage conditions. Plum fruit (‘Reeves’ and ‘Jubileum’) were delivered at a commercial packing house, packed in trays on a flow packaging machine with three different types of absorbent pads placed at the bottom of the trays (standard fruit pad and two humidity control pads with different active compounds; denoted active pad 1 and 2). Trays without pads were controls. After packaging, plums were stored at 3 or 6°C for 7 days and thereafter 2 days at 20°C. Fruit quality, weight loss and amount of fungal decay were recorded at the end of the storage period. The different pads had no significant effects on ripeness state measured by DA-meter and fruit firmness measured at end of storage. The pads had significantly different effect on weight loss, and for ‘Jubileum’ the weight loss was 1.5% for the active pad 1, 2.5% for the active pad 2 and below 1% for the standard pad and the control. Significant effects were found for cultivar and absorbent pads on the total amount of decayed fruit. ‘Jubileum’ was more vulnerable to decay than ‘Reeves’, and the active pad 2 had the lowest number of decayed ‘Jubileum’ fruit stored at 3°C. More work and a cost-benefit analysis should be performed before absorbent pads are recommended for plum fruit.

Sammendrag

Forsøksresultatene som presenteres i denne rapporten er biologisk godkjenningsprøving av soppmidler utført på oppdrag fra Mattilsynet i 2014. Inkludert i rapporten er også forsøk eller egne forsøksledd som grupperes som biologisk utviklingsprøving. Forsøkene er utført etter GEP-kvalitet1 hvis ikke annet er nevnt. Dette innebærer at det er utarbeidet skriftlige prosedyrer for nesten alle arbeidsprosesser. Disse prosedyrene, kalt standardforskrifter (SF’er), er samlet i en kvalitetshåndbok. Denne er delt ut til alle personer som arbeider med utprøving av plantevernmidler. De samme personene har også vært med på et endagskurs i GEP-arbeid.

Sammendrag

Sweet cherry fruit in Norway are graded and packed with chlorinated water according to drinking water standards (max. 2 ppm free chlorine after fruit contact) as a transport medium in parts of the grading lines. A possibility of fruit contamination from fungal pathogens exists in such water. ‘Lapins’ fruit from 10 commercial orchards at each of three packinghouses were put through a simulated sale period (10 days at 2°C and 2-3 days at 20°C) either directly or after being transported on a grading line in 2007. In 2008, fruit were sampled at different times of the day (early, mid and late) and compared with the control. Fruit samples containing 5 x 100 fruits were weighed at time of sampling, after 10 days at 2°C (in a Lifespan bag) and after 2-3 days at 20°C. The number of fruit decayed with fungal pathogens were counted and diagnosed. Total fruit decay in a mean of 3 packing houses x 10 orchards was 14% before packing and 28% after packing in 2007. Brown rot (caused by Monilinia laxa) incidence decreased from 1.1% to 0.3% and Mucor rot (caused primarily by Mucor piriformis) incidence increased from 11% to 26%. In 2008, there were no significant differences between unpacked and packed fruits, or between the different packing hours, on the different fungal diseases or incidence of total fruit decay. These preliminary results indicate that there might be a risk of contamination in seasons with high levels of fruit decay (such as 2007), but in normal seasons a slight chlorination of water is satisfactory to minimize the risk to an acceptable level.

Sammendrag

Sweet cherry fruit in Norway are graded and packed with chlorinated water according to drinking water standards (max. 2 ppm free chlorine after fruit contact) as a transport medium in parts of the grading lines. A possibility of fruit contamination from fungal pathogens exists in such water. ‘Lapins’ fruit from 10 commercial orchards at each of three packinghouses were put through a simulated sale period (10 days at 2°C and 2-3 days at 20°C) either directly or after being transported on a grading line in 2007. In 2008, fruit were sampled at different times of the day (early, mid and late) and compared with the control. Fruit samples containing 5 x 100 fruits were weighed at time of sampling, after 10 days at 2°C (in a Lifespan bag) and after 2-3 days at 20°C. The number of fruit decayed with fungal pathogens were counted and diagnosed. Total fruit decay in a mean of 3 packing houses x 10 orchards was 14% before packing and 28% after packing in 2007. Brown rot (caused by Monilinia laxa) incidence decreased from 1.1% to 0.3% and Mucor rot (caused primarily by Mucor piriformis) incidence increased from 11% to 26%. In 2008, there were no significant differences between unpacked and packed fruits, or between the different packing hours, on the different fungal diseases or incidence of total fruit decay. These preliminary results indicate that there might be a risk of contamination in seasons with high levels of fruit decay (such as 2007), but in normal seasons a slight chlorination of water is satisfactory to minimize the risk to an acceptable level.