Ecology of Xanthomonas campestris pv. vitians in relation to development of bacterial leaf spot of lettuce by Vicky Toussaint.
Bibliographic record
Abstract
In Quebec, bacterial leaf spot of lettuce was observed for the first time in 1994. Since this first mention, the disease has been observed each year and the severity varied with environmental conditions. Little information was available on this disease because until recently it was only sporadically observed around the world following the first mention in 1918. In this project, we found that two groups of Xanthomonas caused the bacterial leaf spot of lettuce according to the BIOLOG profiles. From the results of strain characterization, a semi-selective medium has been developed to detect and quantify X. campestris pv. vitians. This medium is made of maltose, tryptone, methyl green, phosphate salts, amoxicillin, cephalothin, cycloheximide and trace elements. It allowed us to carry out studies on the ecology of the pathogen and on the disease epidemiology. The effect of weather conditions on bacterial population size and the bacterial leaf spot development has been studied. Weather parameters influencing the bacterial population were the number of hours with temperature higher than 28°C, the number of hours with wind velocity lower than 1 km per hour, the number of hours with relative humidity lower than 45% and the minimum relative humidity. The weather parameters that significantly discriminated between disease increase categories were the mean solar radiation, the number of hours with relative humidity higher than 90%, the mean relative humidity and the maximum temperature. Looking at the relationship between X. campestris pv. vitians population size and host plant development, it was shown that both bacterial population size and disease severity increased with leaf age. Mathematical models were developed to show these relationships. This information will be useful in disease management to decide when to apply bactericides and when to harvest. Finally, an exploratory study was conducted looking at the effects of nutrients on the size of saprophytic bacterial
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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 | 0.001 | 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 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".