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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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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.

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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.

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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.

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In organic growing optimized harvest time might be an alternative method for avoiding storage diseases. In three years, organically grown apples of cv. Aroma were picked five times at one-weekintervals, from two weeks prior to, to two weeks after recommended normal harvesttime. The apples were cold stored until February 1 and then kept for two weeksat 20°C. At harvest, fruit quality differed with harvest time, but afterstorage time of harvest had no effect on fruit quality. In mean of three years,fruit decay after storage was significantly higher when picked after, comparedto prior to recommended harvest time. The most important causes of postharvestfruit decay were Colletotrichum acutatum and Neofabraea spp.

Sammendrag

Forsøksresultatene som presenteres i denne rapporten er biologisk godkjenningsprøving av soppmidler utført på oppdrag fra Mattilsynet i 2012. 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.

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Colletotrichum acutatum causes black spot in strawberry (Fragaria × ananassa), but it has also been isolated from 30 other cultivated and non-cultivated plant species in Norway, including almost all fruit and berry crops. Bitter rot, which is caused by C. acutatum, is a severe disease in sweet and sour cherry and apple. We have studied the possibility of cross infection of isolates from other hosts and the potential aggressiveness of these isolates on strawberry. Molecular analyses (AFLP) have shown that isolates collected in Norway could be separated into three major phylogenetic groups in which isolates collected from either Prunus spp., Malus domestica or Fragaria × ananassa predominated. Experiments were carried out under laboratory, greenhouse and field conditions, and strawberry fruits, leaves and stolons were inoculated. All experiments showed that isolates originating from the Fragaria group was much more aggressive than those from the other two groups. If detached strawberry fruits were wounded at time of inoculation, isolates from all groups developed black spot, but disease development went much slower for isolates from the Prunus or Malus groups. If not wounded, there was no or hardly any disease development caused by isolates from the latter two groups. On whole plants inoculated in the greenhouse, isolates in the Fragaria group developed an incidence of 27 to 28 % flower and fruit infections compared to 0 to 4 % for isolates from the other two groups. Under field conditions, Fragaria group isolates developed 50 to 70 % more infected fruit than the others at harvest. On stolons, we inoculated by wounding, and differences in aggressiveness between isolates were only minor. On strawberry leaf laminas, we observed that the ability to colonize the leaf surface was much larger for isolates from the Fragaria group compared to those from the other two groups. However, planting healthy strawberry transplants adjacent to infected sweet cherry trees resulted in latent infections of C. acutatum on strawberry leaves (but no visible infections on fruits), indicating that cross infection between host species may occur under field conditions.

Sammendrag

In Norway, organic apple growers only have sulphur available as a fungicide. When organically grown apples are stored, growers must thus rely entirely on alternative means to reduce the amount of storage decay. It is known that harvest time and calcium content may affect fruit rots in apple. The effect of harvest time on storage decay was assessed during three years. After storage there was a clear increase in fruit decay from the earliest to the latest picking times, both recorded as total decay and for the important storage diseases bitter rot (caused by Colletotrichum acutatum) and lenticell rot (caused by either Phlyctaena vagabunda or Cryptosporiopsis curvispora). In mean of three years apples of cv. Aroma harvested 2 or 1 week prior to normal harvest time, at normal harvest or 1 or 2 weeks afterwards and stored for three months in a ventilated cold store, had 6, 14, 35, 33, and 35% bitter rot, respectively. Similar numbers for lenticell rot (in mean of two years) were 6, 10, 11, 16 and 24%, respectively. Applications of calcium at different times prior to harvest reduced the amount of storage decay in some trials, but not consistently.

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Det vert her rapportert frå forsøk med lagring av eple av sorten Aroma i kontrollert atmosfære ved ulike temperaturar og oksygennivå. Det var dårlegare fruktkvalitet og meir alderssamanbrot i eple lagra i vanleg luft samanlikna med lågt oksygennivå. Mengd bitterrote (den mest vanlege lagersjukdomen i forsøka) var også noko påverka av oksygennivået, men resultata her var ikkje heilt eintydige.

Sammendrag

Artikkelen forteller om Colletotrichum acutatum i norsk jordbærproduksjon, om vertplanter for soppen, om genetiske analyser av soppisolater fra ulike vertplanter og smitteforsøk i jordbær og kirsebær.

Sammendrag

Denne artikkelen forteller om et nordisk prosjekt på Colletotrichum acutatum i jordbær og kirsebær. Artikkelen har vekt på genetisk variasjon og evne til kryss-infeksjon av isolater mellom ulike vertplanter. Hovedkonklusjonen så langt er at isolater fra jordbær er mer aggressive på jordbær enn isolater fra andre vertplanter.

Sammendrag

Colletotrichum acutatum causes bitter rot (often named anthracnose) in cherry and apple. It is the most important fruit decay in sour cherry in Norway and may give severe losses also in sweet cherry and apple. We have found the fungus in all fruit and berry crops grown commercially in the country and on many ornamentals and a few weeds. Single spore isolates frequently developed the ascigerous stage of the fungus (Glomerella acutata) in culture, but it was not detected on apple or cherry plant material. If still attached to the tree, fruits and fruit stalks of sour cherry infected the previous year produced conidial inoculum throughout the entire following season. Also newly infected sour cherry flowers produced conidial inoculum until harvest. Up to 80% of the fruit spurs on sweet cherry had buds infected with C. acutatum in spring. Apple buds also contained the fungus, but to a much lower extent. More than 90% of the sweet cherry leaves could be infected with C. acutatum around harvest in heavily infected orchards. Symptoms on leaves never appeared in the orchards. We also found such asymptomatic leaf infections in apples. Most of the inoculum seemed to be present on the fruit trees themselves. However, initial inoculum in newly established, disease free plantings may be introduced from older fruit trees, ornamentals and weeds in or in close vicinity to the orchards.

Sammendrag

Colletotrichum acutatum is the causal agent of bitter rot in fruit crops (cherry, plum, apple, pear) and black spot in strawberry (Fragaria × ananassa). C. acutatum has also been isolated from a number of other cultivated and non-cultivated plant species; to date the fungus has been found on more than 25 different host species in Norway. The wide host range of C. acutatum necessitates research on the possibility of cross infection between alternative hosts and the potential of isolates of different origin to cause disease in strawberry. Planting healthy strawberry transplants adjacent to infected sweet cherry (Prunus avium) trees resulted in latent C. acutatum infections in the strawberry plants, indicating that cross infections between host species readily occur under field conditions. Molecular analyses (AFLP) have shown that isolates collected in Norway could be separated into three major phylogenetic groups in which isolates collected from either Prunus spp., Malus domestica or Fragaria × ananassa predominated. Two isolates from each of these groups were selected for experiments in vitro and in the field. Preliminary results indicate that isolates from all these groups are able to cause disease in strawberry, but that there may be differences in aggressiveness. In a field trial carried out in 2009 all six isolates caused symptoms in strawberry fruits when spore suspensions were applied three times during fruit development. The isolates from the Prunus group resulted in black spot on 42 and 53% of the strawberry fruits at harvest, while the corresponding numbers were 22 and 54% for the isolates from the Malus group, and 90 and 98% for the isolates from the Fragaria group.

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I integrert plantevern er målet å redusere bruken av og negative sideverknader av kjemiske plantevernmiddel utan å få økonomiske tap i produksjonen. Den som skal utføre integrert plantevern må vite korleis skjedgerarane ser ut, korleis biologien er og kva tiltak som er aktuelle. Denne boka tek for seg viktige skadegjerarar i eple, pære, plomme og søtkirsebær.

Sammendrag

I integrert plantevern er målet å redusere bruken av og negative sidevirkninger av kjemiske plantevernmidler uten å få økonomiske tap i produksjonen. I Landbruks – og matdepartementets Handlingsplan for redusert risiko ved bruk av plantevernmiddel (2004-2008) heter det bl.a. at følgende tiltak bør gjennomføres: ”Oppdatert og tilrettelagt kursmateriell for autorisasjon og integrert plantevern og lett tilgang på anna rettleingsmateriell og informasjon om plantevern”. Denne boka representerer ett av disse tiltakene og er finansiert over denne handlingsplanen. Den som skal utføre integrert plantevern, må vite hvordan skadegjørerne ser ut, hvordan deres biologi er, og hvilke tiltak som er aktuelle. Denne boka omhandler sentrale skadegjørere i eple, pære, plomme og søtkirsebær.

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Plantevernleksikonet. Skadegjørere: Frukttrekreft Epleskurv SølvglansFor hver skadegjører gis en oversikt over symptomer/skadevirkning, vertplanter, overlevelse og spredning og bekjempelse.

Sammendrag

Bitterrote på søtkirsebær er rapportert frå Sveits, Ungarn og Norge. Det er lite publisert kunnskap om sjukdomen på søtkirsebær. Artikkelen gjev eit oversyn over arbeid gjort i Noreg.

Sammendrag

The ascigerous stage (formation of perithecia with viable ascospores) of Colletotrichum acutatum was recently reported to occur on fruits of highbush blueberry (Vaccinium corymbosum) in Norway. When 113 isolates of C. acutatum from various plant species were cultured on strawberry leaf agar, nine developed perithecia with viable ascospores. Four isolates originated from apple (Malus domestica) and one each from sweet cherry (Prunus avium), raspberry (Rubus idaeus), highbush blueberry (Vaccinium corymbosum), hollyberry cotoneaster (Cotoneaster bullatus), and northern dock (Rumex longifolius). Except from blueberry, we never detected the ascigerous stage on decaying fruits or any other parts of the above mentioned plant species. On potato dextrose agar, colour of the underside of the cultures forming perithecia varied from light grey-green to dark grey-green or dark brown-green. Colour of the upperside varied greatly, being dark grey-green, grey-brown, grey, and beige-pink, and only two of the isolates were beige-pink (the raspberry and blueberry isolates). Amplified fragment length polymorphism (AFLP) analysis of the isolates using six primer combinations resulted in 103 clear polymorphic bands. A dendrogram was constructed, and based on cluster analysis using genetic similarity, the isolates could be divided into several clusters. Eight of nine perithecia-forming isolates grouped together in the dendrogram, indicating genetical difference from other isolates. This was also supported by Principal Coordinate (PCO) analysis.

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Søtkirsebærtre vart sprøyta med kalsiumoppløysing ei gong kvar veke frå krunbladfall til to veker før hausting. Frukt frå trea som hadde fått kalsiumtilførsel, hadde høgare innhald av oppløyst turrstoff. Det var ikkje signifikante skilnader i farge, fastleik og syreinnhald. Bladgjødsling med kalsium reduserte utviklinga av kutikulære frakturar på fruktene. Fruktene frå kalsiumsprøyta tre mista meir vekt under lagring enn frukter frå kontrolltre. Hjå kontrollfrukter med mange kutikulære frakturar var vekttapet større enn hjå tilsvarande frukter med få frakturar. Hjå frukter som var tilført kalsium som bladgjødsling, derimot, var det ingen skilnad i vekttapet mellom frukter med mange eller få kutikulære frakturar. Dette indikerer at dei kutikulære frakturane i kalsiumsprøyta frukt var mindre alvorlege (djupe). Innhaldet av fenoliske sambindingar var større i kalsiumsprøyta frukt enn i kontrollfrukt. Færre kutikulære frakturar, mindre alvorlege (djupe) frakturar og auka innhald av fenolar kan vera ulike mekanismar for reduksjonen i risikoen for soppsjukdomar som ein observerer i kalsiumsprøyta søtkirsebær.

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Colletotrichum acutatum is the causal agent of anthracnose/bitter rot in cherry and apple in Norway. It is the most important fruit decay in sour cherry in the country and may give severe losses also in sweet cherry and apple. Single spore isolates frequently develops the ascigerous stage of the fungus (Glomerella acutata) in culture, but it has not yet been detected on apple or cherry plant material. We thus anticipate that the predominant inoculum source is conidia (formed in acervuli). The fungus overwinters in old infected fruits and fruit stalks, in bud shells and in wood of cherry and apple. Infected flowers and leaves may serve as additional inoculum for fruit infections during the growing season. If still attached to the tree, fruits and fruit stalks of sour cherry infected the previous year may produce inoculum of C. acutatum throughout the entire following season. Up to 80% of the fruit spurs on sweet cherry may have buds infected with C. acutatum in spring. Apple buds may also contain the fungus. More than 90% of the sweet cherry leaves may contain C. acutatum around harvest in heavily infected orchards. The entire leaf surface may be infected, but visible infections never appear. We frequently also find such asymptomatic leaf infections in apples. Most of the inoculum seems to be present on the fruit trees themselves. However, initial inoculum in newly planted, disease free plantings may come from older fruit trees, ornamentals and weeds in or in close vicinity to the orchards.

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Det er funne ein klår samanhang mellom når epla er hausta og kor mykje rote som utviklar seg på lager for økologisk dyrka eple. Rett haustetid kan difor vera eit tiltak for å unngå roitning på lager.

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Colletotrichum acutatum vart funne ved undersøkingar av epleknoppar før bryting om våren. Colletotrichum acutatum er årsak til lagersjukdom bitterrote på eple og smitte på knoppar kan vera ei smittekjelde om våren.

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Colletotrichum acutatum fins på alle dei viktige frukt- og bærartane våre og på fleire artar av prydplanter og ugras, men gjer størst skade i kirsebær og eple. Soppen er ei utfordring, fordi han har mange vertplanter, kan leva på enkelte plantedelar utan å utvikla symptom og fordi symptoma ofte ikkje vert synlege på fruktene før etter hausting.

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Ein studerte om bladgjødsling med kalsium påverka fruktkvaliteten hjå plommer og kor haldbare fruktene var etter hausting. Bladgjødsling med kalsium hadde ingen signifikante verknader på fruktkvaliteten. Men kalsiumtilførsel syntest å utsetja mogninga noko (4 av 5 målte faktorar).  Kalsiumhandsaming reduserte rotning under lagring av plommer. Men det var ingen sikre skilnader mellom dei ulike strategiane  som var nytta. I eitt forsøksår var bladgjødsling tidleg i sesongen betre enn handsaming seint med omsyn til rotning etter hausting. I alle forsøka var det  ein tendens til at frukter sprøyta med soppmiddel var mindre utsette for rotning enn kalsiumsprøyta frukter. Men skilnaden var berre signifikant i eitt forsøk.

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For å hindra rôte omfattar eit standard sprøyteprogram i plommer i Norge koparkalk på svellande knoppar, ei sprøyting i bløminga mot monilia og 1-3 sprøytingar mot monilia og gråskimmel mellom bløming og hausting. Frå 1998 har ein registrert kva soppsjukdomar ein finn i plommehagar for handelsdyrking og i forsøksplantingar i Norge; både ved hausting og etter lagring (14 dagar ved 4C og 2-4 dagar ved 20C for å simulera tida i omsetning). Den dominerande sjukdomen var monilia (Monilinia laxa eller M. fructigena). Men ein fann og grønmugg (Penicillium sp.), gråskimmel (Botrytis cinerea), skjeggmugg (Mucor piriformis) og bitterrote (Colletotrichium gloesporioides eller C. acutatum).

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Bruk av plasttunnelar opnar for nye måtar å driva plantevern på, fordi klimaet kan endrast og kontrollerast i større grad enn på friland.

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Foredrag om plantevernutfordringar ved dyrking av frukt, bær og grønsaker i plasttunnelar.

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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.

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Blaut kuldeskade fører år om anna til stor skade i lagra Aroma. Bladgjødsling med kalsium, lagring ved 2 °C (samanlikna med 0,5 °C) og i atmosfære med lågt oksygeninnhald (1-2 % O2) reduserte risikoen for blaut kuldeskade.

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Denne artikkelen har fokus på bruk av høge plasttunnnelar som eit planteverntiltak ved økologisk dyrking av frukt og bær. Ved god klimastyring i plasttunnelar vil problemet med fleire viktige soppsjukdomar kunna reduserast sterkt. Det kan verta større problem med skadedyr, men klimaet i plasttunnelar er gjerne meir optimalt for nyttedyr enn på friland.

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Søtkirsebærknoppar på bukettgreiner og skot vart undersøkt for smitte av Colletotrichum acutatum før knoppsprett i 4 sesongar. Både knoppar frå greiner som var smitta med C. acutatum året før og naturleg infiserte knoppar vart undersøkt. Soppen sporulerte på knoppane med små oransje hornliknande strukturar. Frå naturleg infiserte greiner var det frå 2 til 80% knoppar med sporulering på bukettgreiner  og 0 til 53% på knoppar frå skot. Tilsvarande på knoppar frå greiner smitta året før var 38 til 79% på bukettgreiner og 4 til 45% på skot. På bukettgreinene som har både generative og vegetative knoppar var det mest sporulering på dei generative. Slike infeksjonar på knoppar er truleg ei viktig kjelde til smitte av C. acutatum om våren.

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Artikkelen gjev eit kort oversyn over ulike soppar som er årsak til rote på lagra eple, i tillegg til gode råd for å unngå lagerrote og få epla til å halda seg lenge.

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Artikkelen omhandlar arbeid som er gjort for å finna smitte av Colletotrichum i danske surkirsebærfelt og arbeid vidare framover om Colletotrichum i Norden.

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The aim of this three-year study (2001"2003) was to optimize fungicide application against anthracnose (Colletotrichum acutatum) in sweet and sour cherry orchards. The experimental sprays were applied to trees receiving normal fungicide programmes (grower schedule), although without the use of dithianon, except for the first year where only the experimental applications were applied to the sour cherry trees. Fungicide treatments were applied with either dithianon or copperoxychloride added prior to flowering or with dithianon added after flowering. Spraying with dithianon or copperoxychloride prior to flowering did not significantly reduce anthracnose compared to untreated. Two applications with dithianon during the green fruit stage (from petal fall and during the following 3"4 weeks) greatly reduced anthracnose at harvest. Three applications on green fruit did not reduce disease more than two applications. In sweet cherries, two sprays with dithianon at the green fruit stage in addition to the grower schedule reduced anthracnose at harvest from 14% to 3% in 2002 and from 15% to 1% the following year. In 2001, when very few fruit developed anthracnose, no treatment effects were evident. Treatments on green sour cherry fruit similar to those on sweet cherries reduced the attack of anthracnose from 85% to 42% in 2002 and from 51% to 12% the following year. In 2001, no treatment included only sprays on green fruit. However, one treatment, which included copperoxychloride at bud burst, one application of dithianon during flowering and two applications on green fruits, reduced anthracnose from 27% to 9%. Based on these results, cherry growers are recommended to spray twice with dithianon on green fruit if they have a history of anthracnose in their orchards.

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Angrep av bitterrote på eple etter ei tid på kjølelager er ikkje uvanleg og synest kanskje å vera meir vanleg no enn det var før. Dette kan skuldast endringar i fungicidbruk eller at sortane me dyrkar no er meir mottakelege for denne sjukdomen. Biologien til sjukdomen er ikkje undersøkt under norske tilhøve, men denne artikkelen gjev eit kort oversyn over kunnskap frå andre land. Bitterròtesoppen likar varme og fuktige tilhøve ved infisering og smitten vert spreidd med vassdropar. Hovudsmittekjeldene i andre land er kreftsår og mumifiserte eple. Tilrådde tiltak er fjerning av smittekjelder og sprøyting med fungicid heile sesongen. Sidan bitterròte-soppen er varmekjær vil slike sprøytingar i Noreg vera mest aktuelle frå bløming og fram mot hausting.

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Disease incidence of non-abscised aborted and healthy sweet cherry fruits was investigated during two growing seasons. Fruits from two cultivars (`Van" and `Lapins") were assessed weekly during 4-6 weeks in June and July until 3-4 weeks prior to harvest. The fruits were either surface sterilized (in 0.5% NaOCl) or dipped in distilled water, both for 1 minute, prior to incubation at 20°C for 7 days in saturated air. Visible symptoms of fungal diseases were recorded at day 1, 2, 3, 4, and 7 after incubation. Aborted fruits had much higher disease incidence after incubation than healthy fruits. In 1999 the mean disease incidence was 56.3 and 15.8% in aborted and healthy fruits, respectively (`Van"). The following year, the mean disease incidence in `Van" was 63.0 and 1.4% in aborted and healthy fruits, respectively. Corresponding numbers for `Lapins" in 2000 were 80.6 and 9.0%. Surface sterilized fruits were less decayed than non-sterilized fruit, but differences were not significant. After incubation commenced, symptoms always appeared earlier in aborted compared to healthy fruits. The most frequently observed fungal pathogens were Monilinia laxa, Colletotrichum gloeosporioides, and Botrytis cinerea. A higher disease incidence and more rapid disease development in aborted fruits indicated that these were more vulnerable to fungal colonization than healthy fruits early in fruit development. Thus, non-abscised aborted fruits may act as important hosts of secondary inoculum for healthy fruits.

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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.

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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.

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Mengd angrep av ulike ròtesoppar har vorte undersøkt på underutvikla (aborterte) og normalt utvikla søtkirsebærfrukter av 2 sortar (Van og Lapins) i 3 sesongar (1999-2001) i ei forsøksplanting. Fruktene vart hausta over ein periode på 4 - 7 veker og inkubert 7 dagar ved 20°C i vassmetta luft. Dei vanlegaste ròtesoppane var Monilinia laxa, Colletotrichum gloeosporioides og Botrytis cinerea. I middel av alle observasjonar dei 3 åra var det 51,9 % ròte på underutvikla frukter og 5,2 % på normalt utvikla frukter. I 24 av 25 forsøk var det signifikant meir ròte på underutvikla frukter enn på normalt utvikla frukter. Undersøkingar i to kommersielle søtkirsebærplantingar synte også at underutvikla frukter utvikla meir ròte enn normalt utvikla frukter (6,5 og 4,5 gonger så mykje). Kva tid fruktene aborterte varierte dei to åra dette vart undersøkt og det varierte mellom dei to sortane, men hovudaborteringa fann stad mellom 4 og 8 veker etter full blom. Meir ròte og raskare sjukdomsutvikling i underutvikla frukter tyder på at desse er meir mottakelege for ròtesoppar enn normalt utvikla frukter. Slike frukter kan difor vera ei potensiell smittekjelde for friske frukter i nærleiken.

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Heggeflekk er den mest alvorlege soppsjukdomen på surkirsebær. Angrep kan føra til både omfattande avlingstap i året med infeksjon og i åra etter. Heggeflekk har liknande livvssyklus som epleskurv og difor potensiale til å varslast ved hjelp av automatiserte tenester. Faktorar og kunnskap som er viktige for at varsling av heggeflekk skal kunne etablerast i Noreg er vektlagt i litteraturoversynet.

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Heggeflekk er den mest alvorlege soppsjukdomen på surkirsebær. Angrep kan føra til både omfattande avlingstap i året med infeksjon og i åra etter. Heggeflekk har liknande livvssyklus som epleskurv og difor potensiale til å varslast ved hjelp av automatiserte tenester. Faktorar og kunnskap som er viktige for at varsling av heggeflekk skal kunne etablerast i Noreg er vektlagt i litteraturoversynet.

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Forbrukarane ynskjer plommer dyrka med lite bruk av plantevernmiddel. For å unngå høge tap av plommer under omsetnina av rote,har ein prøvd ut om ekstra sprøyting med kaslium kan vera eit alternativ til bruk av soppmiddel. Ein har samanlikna verknaden av kalsium tidleg i sesongen, seint i sesongen, tilførsel gjennom heile sesongen, soppsprøyta og usprøyta på fruktkvalitet og svinn. Det var ingen signifikante skilnader på kvalitetseigenskapar som refraktometerverdi, syreinnhald, fastleik og farge mellom dei ulike handsamingane. Men frukter som hadde fått kalsium tidleg i sesongen var noko fastare og hadde noko dårlegare fargeutvikling enn andre frukter. Bladgjødsling med kalsium reduserte rotninga etter hausting, men det var ikkje signifikante skilnader mellom tilførsel tidleg eller seint i sesongen.

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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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Bladlus fra familien Aphididae er blant de viktigste skadedyrene i jord og hagebruk i den tempererte klimatiske sonen. De bekjempes hovedsakelig ved bruk av kjemiske insektmidler, men både insektpatogene sopp og parasitoider (insekt parasitter) er viktige for den naturlige kontrollen av bladlus. I et studie ved Planteforsk undersøkes derfor forekomsten og viktigheten av insektpatogene sopper og parasitoider som naturlig fiende til kirsebærbladlus (Myzus cerasi). Foreløpige resultater viser at det for det meste var parasitoider som drepte bladlusa tidlig i sesongen (opptil 30%). Noen få kirsebærbladlus med den insektpatogene soppen Verticillium lecanii ble også funnet tidlig i sesongen. Fra midten av juli ble et betydelig antall kirsebærbladlus (opptil 50%) infisert og drept av insektpatogene sopper innen ordenen Entomophthorales (Entomophthora planchoniana, Erynia neoaphidis og Conidiobolus obscurus). Antall soppdrepte bladlus så ut til å øke mot slutten av juli. I et annet studie ved Planteforsk undersøkes det om bruk av soppmidler og dekking av kirsebærtrærne har effekt på kirsebærbladluspopulasjonen og soppene som dreper kirsebærbladlusa. Foreløpige resultater viser at kirsebærtrær som ikke er dekket mot regn og som ikke behandles med soppmidler muligens kan få en reduksjon i kirsebærbladluspopulasjonen mot slutten av sesongen. Effekten av dekking og soppmidler på soppene som dreper kirsebærbladlusa er enda ikke evaluert.

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Ved kvantifisering av sporeproduksjon av bitterrote (Colletotrichum gloeosporioides) frå ulike plantedelar på surkirsebær (Prunus avium), synte det seg at overvintra mumiefrukter produserte 7-8 gonger fleire sporar enn overvintra visne blomar og fruktstilkar. Sporeproduksjonen avtok raskare på frukter og fruktstilkar som låg på bakken samanlikna med dei som hang i trea, men også på materialet på bakken vart det funne litt sporar heilt fram til hausting.

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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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Arbeidet viser at dekking med plasttak i søtkirsebær reduserer angrep av rotesoppar og kan erstatta bruk av soppmiddel. Di lengre periode fruktene er dekka med tak, di mindre trong er det for soppmiddel. Dekking heilt frå blomstring uten sprøyting gav like godt resultat som dekking 3 til 4 veker før hausting og 2 til 5 sprøytingar.

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Fruktròte er eit av dei viktigaste kvalitetsproblema i søtkirsebærdyrkinga. Dette gjeld både før og etter hausting. Ròtesoppar reduserer avlinga på trea og avgrensar lagringsevna til fruktene. Føremålet med dette arbeidet har vore å kartleggja smittekjelder til ròtesoppane og å undersøkja korleis dyrkingstekniske tiltak i frukthagane påverka mengd ròtning ved hausting og lagring og soleis betra kontrollen av ròtesoppane. Plastdekking før hausting kan påverka ròtning av di plastdekket er ugjennomtrengeleg for vatn. Forsøk med plastdekking 3-4 veker før hausting synte at fruktene hadde fullgod fruktkvalitet og om lag 25 % redusert fruktròte ved hausting.  Ulike dekkesystem påverka mikroklimaet i trea ulikt. Forsøk synte at dekking ved nedbør var eit fullgodt alternativ til om lag 6 sprøytingar med soppmiddel frå bløming til hausting og reduserte fruktròte ved hausting med 13% i høve til udekka. Dekking 5-6 veker før hausting som alternativ til 1-2 sprøytingar reduserte fruktròte ved hausting med 14% i høve til udekka. Plastdekking nær hausting og tidlegare i fruktutviklinga kan altså nyttast både som alternativ og supplement til sprøyting med soppmiddel. Det er vanleg at søtkirsebærfrukter aborterer tidleg i fruktutviklinga. Aborterte frukter har eit svekka vev som lett vert angripe av ròtesoppar. Etter inkubering var det om lag 47% meir fruktròte på aborterte frukter i høve til på velutvikla frukter. Aborterte frukter var til stades i trea frå om lag 3 veker etter full blom til hausting og bør anten fjernast eller mengda bør reduserast ved hjelp av dyrkingstekniske faktorar. Mumifiserte frukter saman med visne bukettgreiner vert rekna for å vera dei viktigaste smittekjeldene for M. laxa om våren. Smitte frå desse var også til stades fram mot hausting. Forsøk synte at smitte i mumiar kunne overleva i fleire år. Smitte frå infiserte blomar var tilstades fram mot hausting og kunne vera ein alternativ overvintringsstad. Det er viktig å fjerna slike smittekjelder. Mikrosprekker i søtkirsebærkutikula kan fremja ròte etter hausting. Dess meir mikrosprekker i fruktoverflata dess meir ròte vart funne ved smitting med ròtesoppane B. cinerea og M. laxa. Frukter med mykje sprekker i fruktkutikula hadde 35% meir ròte enn frukter utan smitte etter inokulering og inkubering. Mengd sprekker i kutikula kan reduserast ved jamn vasstilgong til trea.

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Oversyn over litteratur som omhandlar fruktutvikling hjå ulike steinfrukter, i hovudsak fersken og søtkirsebær. Prosessar i fruktutviklinga frå fruktsetjing til mogning og påverknadsfaktorar er skildra.

Sammendrag

Både insektpatogene sopper og parasitoider er viktige for reguleringen av skadedyr i økologisk og integrert fruktproduksjon. To studier ble gjennomført for å klargjøre biologien til dette komplekset av naturlige fiender og for å undersøke mulighetene for å bruke insektpatogen sopp i biologisk kontroll av kirsebærbladlusa (Myzus cerasi). Foreløpige resultater presenteres i denne artikkelen. I den første undersøkelsen ble forekomsten og viktigheten av insektpatogene sopper og parasitoider som naturlige fiender til M. cerasi undersøk gjennom to påfølgende sesonger. Foreløpige resultater viser at tidlig i sesongen er det først og fremst parasitoider som blir funnet i døde bladlus. Noen få individer infisert med sopp fra klasse Hyphomycetes (Verticillium lecanii) ble også funnet i denne delen av sesongen. Fra midten av juli ble sopp fra orden Entomophthorales (Entomphthora planchoniana, Erynia neoaphidis and Conidiobolus obscurus) funnet i døde bladlus. Antall bladlus drept av sopp ser ut til å øke mot slutten av juli. I studie nummer to ble effekten av soppmidler or dekking mot regn på insektpatogene sopp og tettheten av M. cerasi undersøkt. Foreløpige resultater fra dette studiet indikerer at søtkirsebærtrær som ikke dekkes og som ikke behandles med soppmidler muligens gir et brattere fall i M. cerasi tettheten mot slutten av sesongen. Effekten av soppmidler og dekking mot regn på M. cerasi drept av insektpatogene sopper har ikke blitt evaluert enda.

Sammendrag

Det er gjennomført forsøk med bladgjødsling med kalsium før hausting og dupping av frukter i ulike kalsiumoppløysingar etter hausting av plommesortane "Opal", "Victoria" og "Jubileum". Både tiltak før og etter hausting reduserte svinnet; særleg rôtetap på grunn av Monilinia-arter. Fruktkvaliteten vart ikkje signifikant påverka av tiltak før hausting. Plommer hausta med stilk og i turt ver var mindre utsette for rôtetap etter hausting. Dupping av plommer etter hausting i varmt vatn reduserte og svinnet, men utan å påverka fruktkvaliteten.

Sammendrag

Seasonal production of spores (conidia) of Monilinia laxa (Aderh. & Ruhl) Honey on overwintering mummified fruits, blighted flowers and fruit spurs, and newly infected flowers of sweet cherry (Prunus avium L.) was investigated in Norway in 1997-1999. Infected plant parts were incubated in saturated air for 48 h prior to washing in distilled water, followed by a quantification of conidia from the spore suspensions with a light microscope. Mummified fruits or fruit spurs containing blighted flower and leaf parts, placed on the ground in the spring or the preceding autumn, more quickly depleted their inoculum compared to similar plant parts still hanging in trees. Conidia were produced in high numbers on mummified fruits left hanging in trees for 2-3 years after infection. In 1997, the conidial production on fruit mummies in trees was relatively even during the growing season. The year after, the highest sporulation on mummified fruits in trees occurred prior to flowering, and by harvest the sporulation was reduced by 92%. The wet weather that occurred in 1998 probably depleted the inoculum earlier than in 1997, when the summer was drier. The major production of conidia from fruit spurs occurred prior to or around bloom, and very few conidia were observed at harvest. Infected flower and leaf parts attached to the overwintering fruit spurs contained higher numbers of conidia than the fruit spurs themselves. Flowers infected in the spring produced most conidia during the first two months after infection, however, if remaining attached to the fruit spurs, they produced conidia during the entire season. Infected overwintered flowers produced 3-10% as many conidia as newly infected flowers in May and early June. The maximum production of conidia from single overwintered mummified fruits was more than 10 times the conidial production from an overwintered fruit spur or newly infected flower at their respective times of peak sporulation

Sammendrag

Preharvest cuticular fractures in sweet cherry fruits have been suggested to facilitate pathogen invasion, and a method to classify amount of cuticular fracturing into five categories (1 = no visible fractures, 5 = severe fracturing) has previously been proposed (18). Sweet cherry fruits of the four cultivars Early Burlat, Lapins, Van, and Vista were sorted into these five categories of cuticular fracturing and inoculated with conidial suspensions of either Botrytis cinerea or Monilinia laxa. After incubating the fruits at 20°C and 100% RH for 4 - 7 days, they were assessed for visible fungal growth. Due to quiescent infections of M. laxa, fruits treated with B. cinerea developed more brown rot than grey mold. However, a significant linear relation (p < 0.05) between the amount of cuticular fracturing and fungal infections was obtained in 5 of 7 trials with B. cinerea and in 2 of 4 trials with M. laxa, indicating that fungal infections in sweet cherry fruits may be facilitated by cuticular fractures. Independent of cultivar and year, a significant linear relation was found between the category of cuticular fracturing and percentage of infected fruits after inoculation with both B. cinerea and M. laxa, and in control fruits (p = 0.0001, p = 0.0183, and p = 0.0182, respectively). This is the first report quantifying an increase in fungal infection with increasing amount of cuticular fracturing. The mean difference in fruit rot (%) ± std.dev. between fruits in fracturing categories 1 and 5, expressed as the linear contrast of amount of fruit rot in category 5 minus amount of fruit rot in category 1, was 37.2 ± 7.4 (p = 0.0001), 35.4 ± 11.0 (p = 0.0022), 17.0 ± 6.7 (p = 0.0135), and 29.8 ± 4.7 (p = 0.0001), after treatments with B. cinerea, M. laxa, water control, and for all data pooled, respectively

Sammendrag

Effekten av plastdekking til ulike tidspunkt før hausting gav ein klar reduksjon i talet på frukter angrepne av grå monilia (Monilinia laxa), gråskimmel (Botrytis cinerea) og andre soppsjukdomar.

Sammendrag

Artikkelen gir ein oversikt over forsøk med soppar som gir ròtning i søtkirsebær. Overvintring og konidiedanning gjennom sesongen av Monilinia laxa og Glomerella cingulata som er årsak til respektive grå monilia og bitterròte, er omtala. Vidare er utprøving av nye soppmiddel, effekt av plastdekking mot ròtning og effekt på ròtning av mikrosprekker i fruktene omtala

Sammendrag

Monilinia laxa er årsak til grå monilia hos søtkirsebær (Prunus avium L.). Artikkelen er eit samandrag av undersøking av konidiedanning hos M. laxa frå overvintrande, mumifiserte frukter og fruktgreiner og frå nyleg infiserte blomar. Mumifiserte frukter som vart infiserte året i førevegen, er den viktigaste smittekjelda. Det vert danna konidiar frå slike frukter gjennom heile vekstsesongen.