First Report of Anthracnose of <i>Gaultheria procumbens</i> Caused by <i>Colletotrichum gloeosporioides</i>
Bibliographic record
Abstract
In 2001, a stem canker and dieback associated with a Colletotrichum sp. was observed on Gaultheria procumbens L. (wintergreen) seedlings grown from seed in soilless potting mix at four commercial nurseries in coastal British Columbia, Canada. Black, water-soaked lesions developed into tan cankers girdling stems and petioles, and a black rot extended into the base of leaves. In 2002, a Colletotrichum sp. was isolated from similar stem cankers from wintergreen plants. One flat of healthy, 13-week-old seedlings of G. procumbens (one- to three-leaf stage; approximately 380 seedlings per flat) was inoculated with a mycelial and spore suspension of one of the Colletotrichum sp. isolates at 108 CFU/ml using a hand atomizer. The flat was covered with black plastic for 24 h after inoculation and maintained in a growth chamber at 22°C with overhead watering. After 7 days, 98% of seedlings in the inoculated flat were necrotic with abundant sporulation of the Colletotrichum fungus on stem and petiole lesions. Plants in noninoculated flats remained healthy. Reisolation of the fungus from symptomatic tissues confirmed the causal agent to be Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz, based on morphology (1,2) and polymerase chain reaction (PCR) using the species-specific primer CgInt (3). Cylindrical, hyaline, aseptate conidia measuring 16 to 20 × 4 to 6 μm were produced in acervuli with setae. Perithecia of the teleomorph, Glomerella cingulata, observed on the plants and in culture, measured 100 to 128 μm in diameter and contained acsi measuring 56 to 60 × 8 to 10 μm. Ascospores were hyaline, unicellular, slightly curved, and measured 18 to 20 × 4 to 6 μm. Subsequently, a single-spore isolate of the fungus was used to inoculate 21-week-old seedlings in the greenhouse as described above. Four inoculated and four noninoculated half-flats containing an average of 160 seedlings each were randomized on the greenhouse bench and maintained at 22°C with daily overhead misting. Stem and petiole cankers appeared on 65.1% of inoculated seedlings at 10 days after inoculation (mean of four inoculated half-flats); increasing to 90.5% at 14 days. At 14 days, 5.9% of seedlings in four noninoculated half-flats were also symptomatic, possibly from spore contamination as a result of overhead watering. To our knowledge, this is the first confirmation of the causal agent of wintergreen seedling death in seed propagation nurseries in British Columbia. References: (1) J. E. M. Mordue. Glomerella cingulata. No. 315 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1971. (2) B. C. Sutton. The Coelomycetes. CAB International Publishing, New York, 1980. (3) P. Talhinhas et al. Phytopathology 92:986, 2002.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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.
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".