A Nylon Membrane Bag Assay for Determination of the Effect of Chemicals on Soilborne Plant Pathogens in Soil
Bibliographic record
Abstract
A new nylon membrane bag (NMB) assay was developed for studies to determine the effect of chemicals added to soil on survival of soilborne plant pathogens. The rapid and effective assay can be used to study organisms for which there are no selective media or for which a selective medium is expensive or difficult to prepare. This assay consists of placing pathogens inside a bag made of small-pore (0.22-μm) nylon filtration membrane, which is placed in soil and later retrieved to determine survival of the pathogens on nonselective media. Chemicals but not other microorganisms can enter the bag from the soil. Using this assay, Streptomyces scabies, Fusarium oxysporum f. sp. lycopersici race 3, and Ralstonia solanacearum were successfully recovered from soil after 72 h as demonstrated by growth on a semiselective Streptomyces medium (S. scabies) or nonselective potato dextrose agar medium (F. oxysporum f. sp. lycopersici race 3 and R. solanacearum) with minimal microbial contamination. Addition of acetic acid (200 mM) to soil killed 100% of S. scabies. SPK (a mixture of organic chemicals) at a concentration of 1,500 mg kg–1 of soil killed 83.3% of F. oxysporum f. sp. lycopersici race 3 culture plugs, 100% of F. oxysporum f. sp. lycopersici race 3 spores, and 97.2% of R. solanacearum cells. SPK at 1,000 mg kg–1 of soil killed 50% of F. oxysporum f. sp. lycopersici race 3 culture plugs, 68.2% of F. oxysporum f. sp. lycopersici race 3 spores, and 12% of R. solanacearum. Benlate (500 to 1,500 mg kg–1 of soil) did not kill the culture plugs of F. oxysporum f. sp. lycopersici race 3 but reduced the growth rate of F. oxysporum f. sp. lycopersici race 3. Benlate (500, 1,000, and 1,500 mg kg–1 of soil) reduced F. oxysporum f. sp. lycopersici race 3 spore germination by 39.4, 49.3, and 50.4%, respectively. Streptomycin sulfate (1,500, 800, 400, and 200 mg kg–1 of soil) caused 75.3, 21, 11.9, and 0.9% mortality, respectively, of R. solanacearum.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.004 |
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".