Studies of plant host preferences of the stem Nematodes, Ditylenchus Weischeri and D. Dipsaci
Bibliographic record
Abstract
The occurrence of D. weischeri Chizhov, Borisov & Subbotin, a newly described stem nematode species of creeping thistle (Cirsium arvense L.), and D. dipsaci (Kühn) Filipjev, a pest of garlic and quarantine parasitic species of many crops, has been reported in Canada. This research was conducted to determine if D. weischeri is a pest of agricultural crops, especially yellow pea (Pisum sativum L.) in the Canadian Prairies. Significant (P < 0.05) slight reproduction (1 < ratio of final to initial population < 2) of D. weischeri occurred on two (Agassiz and Golden) of five varieties of yellow pea examined. Other annual pulse and non-pulse crops, including common bean, chickpea, lentil, spring wheat, canola, and garlic were non-hosts for D. weischeri. Conversely, a range of reproduction responses to D. dipsaci was observed with all pulse crops being a host of the nematode. Ditylenchus weischeri was not a seed-borne parasite of yellow pea, unlike, D. dipsaci which was recovered from seed. Conversely, D. weischeri and not D. dipsaci was recovered from creeping thistle seeds. In callused carrot disks, with no addition of medium, an increase of 54 and 244 times the addition density of 80 nematodes was obtained for D. weischeri and D. dipsaci, respectively, after 90 days. Temperature had a significant influence on the development of D. weischeri and D. dipsaci in yellow pea. Development of D. weischeri did not proceed past adult stage at 17 and 22°C whereas a minimum generation time of 30 days was apparent at 27°C with the associated accumulated growing degree-days of 720 degree-days (above a base temperature of 3°C). The minimum generation time for D. dipsaci was 24, 18 and 22 days with 336, 342 and 528 degree-days at 17, 22 and 27°C, respectively. In field microplots, grain yield of yellow pea were not significantly affected by addition density of D. weischeri. At harvest, the total number of recovered nematodes per plant was not significantly different than the added at the start. The results of these studies confirm that D. weischeri is unlikely to be a pest of yellow pea for weather conditions of the Canadian Prairies.
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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".