First Report of Powdery Mildew Caused by <i>Erysiphe cichoracearum</i> on Creeping Thistle (<i>Cirsium arvense</i>) in North America
Bibliographic record
Abstract
Creeping or Canada thistle (Cirsium arvense (L.) Scop.) is a perennial weed of Eurasian origin that arrived in North America as early as the 1700s (3). Spreading by seeds and rhizomes, it is now widely distributed in Canada, Alaska, and 40 other states. It is apparently absent from Texas, Oklahoma, Louisiana, Mississippi, Alabama, Georgia, Florida, and South Carolina (1). Powdery mildew is common on C. arvense in Europe, but it has never been observed in North America (4). In Europe and Asia, powdery mildew of C. arvense is caused by any one of the following fungi: Leveillula taurica, two species of Sphaerotheca, and varieties of Erysiphe cichoracearum and E. mayorii. Specimens of C. arvense infected with powdery mildew (deposited in the U.S. National Fungus Collections as BPI 843471) were collected in the fall of 2003 near Moscow, ID and in two areas in Oregon (the canyon of the Grande Ronde River and near the base of the Wallowa Mountains). Mycelium and cleistothecia were observed on stems and upper and lower surfaces of leaves. The mean diameter of the cleistothecia was 122 (±11.6) μm. Basally inserted, mycelioid appendages were hyaline or brown and varied considerably in length, but most were in the range of 80 to 120 μm. Asci averaged 58 (±5.5) μm × 35 (±4.1) μm in length and width, respectively. Each ascus bore two ascospores averaging 23 (±1.4) μm × 14 (±1.7) μm. Conidia averaged 30 (±3.0) μm × 14 (±0.8) μm. The specimens fit the description of E. cichoracearum DC. (2). Because the length/breadth ratio of conidia is greater than 2, the specimens could be further diagnosed as E. cichoracearum var. cichoracearum (2). Also noteworthy was the presence of the hyperparasitic Ampelomyces quisqualis Ces. ex Schlechtend. E. cichoracearum is thought to be a cosmopolitan powdery mildew of broad host range, but this concept is difficult to reconcile with the absence of mildew on North American populations of C. arvense for more than 200 years. References: (1) Anonymous. USDA Natural Resources Conservation Service Plants Profile for Cirsium arvense. On-line publication, 2003. (2) U. Braun. A monograph of the Erysiphales (powdery mildews), J. Cramer, Berlin-Stuttgart, 1987. (3) G. Cox. Alien Species in North America and Hawaii, Island Press, Washington, D.C., 1999. (4) D. F. Farr et al. Fungal Databases, Systematic Botany and Mycology Laboratory, ARS, USDA. On-line publication, 2003.
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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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".