Management strategies to reduce losses caused by rhizoctonia seedling blight of field pea
Bibliographic record
Abstract
Seedling blight can cause substantial reductions in stand density of field pea on the Canadian prairies. Ninety-four isolates of Rhizoctonia solani were obtained from soil samples collected from 37 pea fields in 1999 in Alberta, Canada. Sixty isolates were characterized as anastomosis group (AG)-4 and 12 isolates as AG-2-1. Some of these isolates caused severe pre-emergence damping-off and were classified as highly pathogenic; 41 of the 44 highly pathogenic isolates were AG-4 and three were AG-2-1. Two highly pathogenic AG-4 isolates were used to assess the effect of inoculum density on survival and growth of field pea seedlings, and the impact of seeding date, seeding depth, soil temperature, seed damage, seed treatments and seeding density on seedling blight and root rot injury. As inoculum density increased, so did root rot severity, while seedling establishment, shoot dry weight and root dry weight declined. Under controlled conditions, seedling establishment in the noninoculated control increased as soil temperatures increased, but establishment and growth declined in inoculated treatments. In a temperature gradient study, seedling infection was highest when mean daily temperatures were 17.5°C or higher. In field trials over 8 station years, delayed seeding often resulted in reduced seedling establishment in inoculated treatments, although this trend was not consistent across sites or years. Seed yield consistently declined with later seeding dates. Seed treatment with fungicides (carbathiin + thiram, metalaxyl) improved establishment and productivity in inoculated treatments, especially where seed was damaged prior to planting. Seeding depth had no impact on root rot severity. Emergence and seed yield increased with seeding density, but increasing density beyond 90 seeds m -2 did not result in proportionately higher yields. These results indicate that a combination of seed treatment and early seeding can reduce Rhizoctonia injury to pea seedlings under field conditions. Key words: Pisum sativum, Rhizoctonia solani (AG-4), management, seeding depth, seeding rate
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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".