The impact of herbicide-resistant canola systems on the weed community dynamics in the Canadian Prairies
Bibliographic record
Abstract
Increased adoption of no-till and extensive cultivation of herbicide-resistant (HR) crops in low diversity rotations are some transformations that occurred during the 1970s–2000s in western Canada. Historical data analysis of weed survey data (Saskatchewan, Manitoba, and Alberta) in canola crops and a canola rotation field experiment were used to understand how tillage, herbicide-resistant cropping systems, and the temporal frequency of canola in the rotation can impact weed abundance, composition, and diversity in the Canadian prairies. Weed survey data revealed that the spatial frequency of many weed species declined in years after 1995 compared with before 1995, the year HR cultivars were introduced. False cleavers ( Galeum spurium L .) and volunteer wheat ( Triticum aestivum L.) were the only species showing a continuous increase in frequency throughout the surveyed years. Species richness showed no trajectories but varied depending on climatic conditions. Roundup-Ready (RR) systems were associated with green foxtail ( Setaria viridis L.) irrespective of their frequency in the rotation. Continuous canola systems had an obvious association with chickweed ( Stellaria media L.) regardless of herbicide systems. Wild oats ( Avena fatua L.) were predominant in the longer rotations with glufosinate and imidazolinone-resistant canola. In the field study, weeds associated before in crop herbicide application were relatively controlled after herbicides were applied, except for foxtail barley ( Hordeum Jubatum L.), which was not controlled in most HR systems. Overall, both weed survey data and field experiment data revealed greater control of most weed species due to the adoption of HR canola cultivars and the associated cultural practices.
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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 | 0.003 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".