A review of the recruitment biology of winter annual weeds in Canada
Bibliographic record
Abstract
Typically, summer annual weeds have been the primary management target for field crop farmers in Canada, but with changes in cropping systems and with acknowledged global climate change there will be an increasing need to consider the management of species that are present very early in the spring, including winter annual weeds. Knowledge of weed recruitment biology and emergence patterns can be used to guide weed management practices. A review was conducted of the recruitment biology of winter annual weeds in Canada. The key finding was that all of the significant winter annual weeds in Canadian agriculture are facultative, with the majority of species emerging at two peak periods, April-May and September-October. For the weed species included in this review, the information available on recruitment and seed biology was far from comprehensive, and for some species there was very little published information, in particular on specific base temperatures for germination, documented field-based emergence periods and data that could be used to create simple predictive population dynamics models, including fecundity (× environment), seed longevity and overwintering probability. This is particularly true with respect to information in Canadian agricultural contexts. A number of questions result from this review, a key one being whether spring versus fall emergence creates significant differences in fundamental biological characteristics of winter annual weeds including seed dormancy status, microsite requirements, phenology, plant vigour and competitive ability. Given that none of the winter annuals in Canada are constitutive and given ongoing climate change, farmers in Canada should be careful not to encourage summer annuals to become winter annuals. Movement away from fall weed management, including tillage and repeated sowing of winter annual crops will encourage facultative winter annual behaviour. In addition, farmers should be wary of invasion by populations of persistent winter annuals including stinkweed, chickweed and American dragonhead.Key words: Facultative winter annual, dormancy, microsites, emergence pattern, seed rain, seed longevity, weed management
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 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".