Characterization of <i>Plasmodiophora brassicae</i> pathotypes from western Canada in 2019–2020
Bibliographic record
Abstract
Clubroot, caused by Plasmodiophora brassicae, is a major soilborne disease of canola (Brassica napus) on the Canadian Prairies. Most canola cultivars carry what is now referred to as ‘first-generation’ resistance, which represents the most widely used clubroot management tool. Unfortunately, new pathotypes of P. brassicae have emerged that can overcome this resistance. By 2018, 36 unique pathotypes of P. brassicae had been identified on the Prairies based on their virulence on the Canadian Clubroot Differential (CCD) set, with pathotypes 3A, 3D and 3 H being predominant. Since the virulence of P. brassicae populations can shift rapidly in response to host selection pressure, continued pathotype monitoring is important for resistance stewardship. Clubbed roots were collected from 133 canola crops (126 in Alberta, 6 in Saskatchewan, 1 in Manitoba) in 2019 and 127 crops (113 in Alberta, 13 in Saskatchewan, 1 in Manitoba) in 2020, and evaluated for their CCD pathotype designations. Twenty-five unique pathotypes were identified across the sampled crops over the two years of the study; these included seven novel pathotypes, six of which could overcome first-generation resistance (3C, 8 G, 8I, 9D, 9E and 9F). While pathotypes 3A, 3D and 3 H continued to be identified frequently in 2019 and 2020, several others, most notably pathotype 8E (virulent on hosts with first-generation resistance), had also become more common by 2020. The results indicate the continued emergence of new P. brassicae pathotypes on canola.
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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 | 0.002 | 0.003 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".