Diversity in virulence and metalaxyl-m sensitivity of <i>Phytophthora rubi</i> isolates has implications for raspberry root rot and wilting complex management
Bibliographic record
Abstract
Raspberry root rot and wilting complex (RRWC), primarily caused by <i>Phytophthora rubi</i>, is the most important disease for raspberry producers in Canada. There is currently little to no information on phenotypic diversity or sensitivity to metalaxyl-m of <i>P. rubi</i> isolates affecting raspberries in Canada. This study was conducted to understand the diversity in virulence and sensitivity to metalaxyl-m of <i>P. rubi</i> populations collected from diverse raspberry cultivars, fields, and locations during 2018–2020. All isolates of <i>P. rubi</i> (<i>n</i> = 24) were pathogenic on ‘Chemainus’ raspberry and showed significant variation (<i>P <</i> 0.05) in days to first foliar symptom development (DFSD) and progress in wilting index, as indicated by relative areas under disease progress curves (rAUDPC). Principal component analyses identified that root rot index, rAUDPC, DFSD, and percentage reduction in root length and weight were important variables in assessing pathogen virulence. Metalaxyl-m sensitivity was assessed using a radial growth assay and effective concentrations that inhibited 50% of mycelial growth (EC<sub>50</sub>) were determined for 44 isolates. The EC<sub>50</sub> values ranged from 0.035–4.71 µg mL<sup>−1</sup> with a mean value of 0.793 µg mL<sup>−1</sup>. About 61% of the isolates were very sensitive (EC<sub>50</sub> values <0.20 µg mL<sup>−1</sup>), 25% of isolates were considered sensitive (EC<sub>50</sub> values of 0.21–1.18 µg mL<sup>−1</sup>), and 14% of isolates showed reduced sensitivity to metalaxyl-m (EC<sub>50</sub> value range of 1.19–4.71 µg mL<sup>−1</sup>). Knowledge of pathogen phenotypic diversity will be useful for raspberry breeders in screening genotypes against RRWC and the results of the fungicide sensitivity study will be useful in developing management strategies for RRWC.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".