First record of <i>Septoria rudbeckiae</i> on <i>Rudbeckia</i> in the United Kingdom
Notice bibliographique
Résumé
Species of Rudbeckia, often known as black-eyed Susan or coneflower, are used as bedding plants in UK gardens. The large, daisy-like flowerheads typically have bright yellow petals and a conspicuous black centre which may be raised into a cone shape. During the summer of 2016, Rudbeckia fulgida var. sullivantii cv. Goldsturm plants, purchased in the preceding May from a nursery in south-east England, were observed with black leaf spots in outdoor beds at the Royal Horticultural Society (RHS) Garden Wisley. Lower leaves exhibited small black lesions in July, which coalesced as the season progressed leading to complete necrosis of the bottom leaves and spotting on higher leaves. Spots showed no halos and became necrotic only later in the season. Flowering did not appear to be reduced. Pycnidia within the leaf spots were epiphyllous, 50-75 μm diameter, with a neck protruding slightly above the leaf surface. Conidia were filiform, 30-60 times 1.5-2 μm, with three septa. A single-spore isolate was obtained on water agar and cultured on potato dextrose agar. Living cultures were deposited in the RHS culture collection held at RHS Garden Wisley (Accession No. RHS454672) and at Westerdijk Fungal Biodiversity Institute, Netherlands (Accession No. CBS145765). The internal transcribed spacer (ITS) region of rDNA, the β-tubulin (Btub) gene and the translation elongation factor 1-alpha (EF1) gene were amplified using the primers ITS4:ITS5, T1:B-Sandy-R, and EF1-728F:EF2, respectively, according to the method by Verkley et al. (5). The DNA amplicons were sequenced (GenBank Accession Nos. MN093336 (ITS), MN105980 (Btub) and MN166626 (EF1)). The ITS sequence differed by one base pair from the only ITS sequence available for Septoria rudbeckiae (JQ677043). No previous sequences were available for comparison for Btub and EF1 and none of the available sequences had more than 90% identity. Pathogenicity was confirmed by spraying Rudbeckia fulgida sullivantii ‘Goldsturm’ plants with a conidial suspension (1 × 106 conidia/ml) prepared from spores from 21-day-old cultures on potato dextrose agar, incubated at 20°C with a 12 hr light/ 12 hr dark cycle. Plants were kept in high humidity for 72 hr after inoculation. After four weeks, black lesions were observed on leaves. Pycnidia and conidia consistent with S. rudbeckiae were found within each lesion. Control plants sprayed with sterilised water showed no symptoms. Septoria rudbeckiae was described from the USA (Ellis & Halsted, 1) where it is now widespread causing disfigurement of Rudbeckia in gardens. Although the fungus has been recorded from a number of different Rudbeckia species, Rudbeckia fulgida var. sullivanti cv. Goldstrum has been recognised in the USA as one of the most susceptible cultivars. Septoria rudbeckiae has also been reported from Canada, Bulgaria and Romania (Farr & Rossman, 2), Turkey (as Septoria sp.; Gumrukcu, 3) and Korea (Park, 4). To our knowledge, this is the first report of S. rudbeckiae in the United Kingdom. The authors would like to thank Jane Renshaw for aid in preparation of fungal cultures.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,002 | 0,001 |
| Études des sciences et des technologies | 0,002 | 0,001 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,007 | 0,003 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».