First record of <i>Septoria rudbeckiae</i> on <i>Rudbeckia</i> in the United Kingdom
Bibliographic record
Abstract
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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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot 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.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.003 |
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.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
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".