First Report of Leaf Spot Caused by <i>Septoria erigerontis</i> on <i>Erigeron strigosus</i> in Korea
Bibliographic record
Abstract
Erigeron strigosus Muhl. ex Willd., known as daisy fleabane, is native to North America and was accidently introduced to Korea in the 1990s (2). It is increasingly invasive in natural and managed ecosystems throughout Korea. In June 2011, a leaf spot was first observed on daisy fleabanes growing wild in Hongcheon County of Korea. A voucher specimen was deposited in the Korea University Herbarium (KUS-F25759). Symptoms developed on lower leaves as small, distinct, reddish brown lesions, which enlarged progressively and turned into pale, dull brown spots surrounded by dark purplish-brown margins. Black pycnidia became visible in the lesions. Pycnidia were epigenous, occasionally hypogenous, scattered, dark brown to rusty brown, globose, embedded in host tissue or partly erumpent, 60 to 160 μm in diameter, with ostioles measuring 10 to 30 μm in diameter. Conidia were straight to mildly curved or even flexuous, guttulate, hyaline, 30 to 75 × 1.5 to 2 μm, and one- to seven-septate. Based on the morphological characteristics, the fungus was consistent with Septoria erigerontis Peck (3,4). Conidia were harvested from cirrhi of pycnidia on leaf lesions with a drop of sterile water and then directly streaked onto water agar media using a bacterial loop. Isolates were incubated at 24°C for 48 h. Germinating conidia were individually transferred to potato dextrose agar (PDA) plates. An isolate was deposited in the Korean Agricultural Culture Collection (Accession No. KACC46120). Genomic DNA was extracted using the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA). The internal transcribed spacer (ITS) region of rDNA was amplified using the ITS1/ITS4 primers and sequenced. The resulting sequence of 505 bp was deposited in GenBank (Accession No. JX480493). A GenBank BLAST search was conducted with the 505-bp sequence showing 100% identity with the sequences of S. erigerontis ex Erigeron annuus (EF535638, GU269862). Pathogenicity was tested by spraying leaves of three potted plants with a conidial suspension (2 × 105 conidia/ml) harvested from a 4-week-old PDA culture. Control leaves were sprayed with sterile distilled water. The plants were placed in a dew chamber at 26°C in darkness and continuous dew for the first 24 h and then moved to a greenhouse bench. After 7 days, leaf spot symptoms identical to those observed in the field developed on the leaves inoculated with the fungus. No symptoms were observed on control plants. S. erigerontis was reisolated from the lesions of inoculated plants, fulfilling Koch's postulates. A leaf spot disease of E. strigosus associated with S. erigerontis has been reported in the United States and Canada (1). To our knowledge, this is the first report of leaf spot on E. strigosus caused by S. erigerontis outside of North America as well as in Korea. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication. ARS, USDA, Retrieved June 2, 2012. (2) S. H. Park. Colored Illustrations of Naturalized Plants of Korea. Ilchokak Publishers, Seoul, Korea, 1995. (3) M. J. Priest. Fungi of Australia: Septoria. ABRS/CSIRO Publishing, Melbourne, Australia, 1997. (4) E. Radulescu et al. Septoriozele din Romania. Ed. Acad. Rep. Soc. Romania, Bucuresti, Romania, 1973.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".