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Record W2145252679 · doi:10.5897/jaerd12.062

Neonectria-canker on trees in Norway

2012· article· en· W2145252679 on OpenAlexaboutno aff
Venche Talgø

Bibliographic record

VenueJournal of Agricultural Extension and Rural Development · 2012
Typearticle
Languageen
FieldBiochemistry, Genetics and Molecular Biology
TopicPlant Pathogens and Fungal Diseases
Canadian institutionsnot available
Fundersnot available
KeywordsBiologyBotanyCankerPrunusHorticulture

Abstract

fetched live from OpenAlex

Neonectria spp. have been found on a number of tree species in Norway. Neonectria ditissimais commonly detected from diseased trees in apple orchards and a N. ditissima–like species has caused an epidemic on white fir (Abies concolor). In Norway, Neonectria spp. attack numerous plant species including true fir (Abies spp.), sycamore maple (Acer pseudoplatanus), alder (Alnus glutinosa) (Figure 1), dogwood (Cornussp.), ash (Fraxinus excelsior), holly (Ilex aquifolium) (Figure 2), apple (Malus × domestica),spruce (Picea abies), poplar (Populus sp.), bird cherry (Prunus padus), pear (Pyrus sp.), and rowan (Sorbus aucuparia). Attacks by Neonectria spp. may result in canker wounds and dieback. Red fruiting bodies (perithecia) containing asci and ascospores are often present. Usually they form clusters that are clearly visible to the naked eye. In culture, Neonectria spp. produce microconidia (Cephalosporium spp.) and macroconidia (Cylindrocarpon cylindrioides). Neonectria-canker is a serious problem in Norwegian apple orchards (Figure 3), and in 2010 we investigated if host plants other than apple trees were potential inoculum sources. We sequenced the internal transcribed spacer (ITS)-regions from Neonectria cultures isolated from apple trees and two other host plants in the rose family (Rosaceae); rowan (S. aucuparia)(Figure 4) and bird cherry (P. padus) (Figure 5). Cultures from all 3 hosts produced floccose, white mycelium. The cultures had identical sequences and they were identical to the sequences of N. ditissima (syn. Neonectria galligena) deposited in GenBank. Inoculation tests have not yet taken place, thus, we have no indications that cross infections take place in nature. Further research is needed to find out if infected rowan or bird cherry in the vicinity of apple orchards may increase the disease pressure. Interestingly, cultures isolated from dying conifers in Norway in 2008 differed from N. ditissimaby five out of the 550 base pairs included in the ITS-sequence. Previously, Neonectria fuckelianahas been reported on spruce species in Norway, and on spruce and fir species in other countries, but N. fuckeliana differs by more than 20 base pairs from the N. ditissima-like isolates we obtained from conifers in 2008. The N. ditissima-like fungus might be a new species related to N. ditissima, possibly imported to Norway. N. ditissima has to our knowledge never been described as a pathogen on conifers, but the N. ditissima-like fungus we isolated from conifers in 2008 was clearly pathogenic. We first discovered a serious disease outbreak on white fir (Abies concolor) in southern Norway (Figure 6), and the N. ditissima-like fungus was isolated from dying trees in two counties in south western and four counties in south eastern Norway. Both old and young trees were dead or dying. The N. ditissima-like fungus was later isolated from Siberian fir (A. sibirica), subalpine fir (A. lasiocarpa), and Norway spruce (Picea abies) in south eastern Norway. Perithecia in canker wounds from the conifer samples were dark around the ostiole. This morphological characteristic is known from N. ditissima, but not from N. fuckeliana. Sequencing showed that all the Neonectria-isolates from different conifer hosts in 2008 were identical in their ITS-region. The cultures were white. Cultures from N. fuckeliana are brownish. N. fuckeliana is common on Norway spruce in our country (Roll-Hansen and Roll-Hansen, 1995), and commonly associated with dieback on white fir in Europe and western North America (Callan, 1997). In Canada, N. fuckeliana caused dieback on subalpine fir (A. lasiocarpa) (Funk, 1981). Inoculation tests with N. ditissima-like isolates were carried out in 2009 on subalpine fir, white fir, and Norway spruce. Map pins (16 mm SHF top grip map pins, Palsboda, Sweden) were used to inoculate and easily trace the inoculation points. The pins were autoclaved and placed on potato dextrose agar (PDA) together with an agar plug (0.5 mm in diameter) from theNeonectria–culture to be tested. After approximately one week at room temperature the pins were covered with mycelium, and the needle tips were inserted into the bark or dormant buds (3 pins or more were inserted per plant – depending on the size and shape of the plant). As a control, unwounded trees or trees wounded by autoclaved map pins from sterile PDA were used. The fungus was pathogenic on all three fir species tested. Figure 7 shows symptoms on inoculated subalpine fir. Control trees showed no symptoms. Key words: Neonectria fuckeliana, Neonectria ditissima, Abies, Picea, Malus, Sorbus, Prunus.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Direct model labels (unvalidated)

Per-model category and study-design labels from the labeling rounds. They are machine output, unvalidated, and the disagreement between models ships as data. No study design here is MEDLINE-validated yet.

Model armCategoriesStudy designConfidence
gemmano category
Domain: not available · Genre: Empirical
About the Canadian research system: no · About a Canadian topic: no
Observationallow
gptno category
Domain: not available · Genre: Empirical
About the Canadian research system: no · About a Canadian topic: no
Bench or experimentallow
models splitAgreement compares identical category sets and study designs across arms.

Full frame machine prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Observational · Consensus signal: none
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.010
Threshold uncertainty score0.019

Distilled classifier scores by category (both heads)

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0010.000

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.009
GPT teacher head0.217
Teacher spread0.208 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Labeled directly by 2 models reading the full record.

The models applied no category: nothing in the taxonomy fit this work.

The models disagree on parts of this classification; every voice is preserved in the section at the end of the page.

Study designObservational · Bench or experimental
Domainnot available
GenreEmpirical

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations7
Published2012
Admission routes1
Has abstractyes

Explore more

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