Assessing and managing metalaxyl-m resistant strains of the potato pink rot pathogen Phytophthora erythroseptica in Canada
Bibliographic record
Abstract
Phytophthora erythroseptica Pethybr. is the causal agent of potato pink rot which\nresults in a wet rot and complete breakdown of tubers leading to significant yield losses in field and storage settings. Traditionally, products containing metalaxyl and later its enantiomer metalaxyl-m have been used to manage P. erythroseptica. However, in recent years, metalaxyl-m resistant strains of P. erythroseptica have been recovered in the United States and Atlantic Canada. A national survey was conducted from 2013 to 2016 to assess the distribution of metalaxyl m-resistant populations in Canadian potato- producing regions. The survey recovered resistant isolates from Prince Edward Island, Nova Scotia, New Brunswick, Ontario, Manitoba, and Alberta. As a result of this survey, resistant isolates were identified for the first time in Ontario, Manitoba, and Alberta. Due to the increasing frequency of metalaxyl-m resistant populations there is a need for alternative management strategies. Therefore, registered and experimental fungicides were assessed for the capacity to control the pink rot pathogen in field and storage settings. The fungicides evaluated were metalaxyl-m, oxathiapiprolin, fluopicolide, phosphites, and a biological control agent Bacillus subtilis. The EC50 values (the fungicide concentration inhibiting mycelial growth of the pathogen by 50% relative to the 0 μg mL-1 control) for two strains (PE9913; metalaxyl-m sensitive and PE1204; metalaxyl-m resistant) of P. erythroseptica exposed to metalaxyl-m, oxathiapiprolin, fluopicolide, and phosphites were determined using an amended agar assay. The EC50 values were 0.057 and 842.41 ppm, respectively, for the metalaxyl-m sensitive and metalaxyl-m resistant isolates grown on metalaxyl-m amended media. The EC50 values of the metalaxyl-m sensitive and metalaxyl-m resistant isolates exposed to oxathiapiprolin, fluopicolide, or phosphite were <0.0001 ppm, 0.064 to 0.128, and 112.0 to 147.6 ppm, respectively. Field trials were established from 2014 to 2016 to evaluate the fungicides for their efficacy in managing pink rot in the field. Significant control of pink rot was achieved by in-furrow treatments of oxathiapiprolin or fluopicolide, or phosphites applied foliarly. Some pink rot suppression was achieved following application of Bacillus subtilis, but of significantly smaller degree than provided by the other products. Storage trials were established in 2016 and 2017 to assess the capacity of these fungicides to inhibit P. erythroseptica infection of tubers inoculated with zoospores prior to storage. Significant control of pink rot was achieved with treatments of oxathiapiprolin, fluopicolide, phosphites, and to lesser extent Bacillus subtilis under storage conditions. The results of this study show that metalaxyl-m resistant populations of P. erythroseptica are increasing in frequency in Canadian potato-producing regions. However, management of these populations can be achieved with use of currently registered and experimental products in production settings.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 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".