First Report of Fludioxonil-Resistant Isolates of <i>Fusarium</i> spp. Causing Potato Seed-Piece Decay
Notice bibliographique
Résumé
Potato (Solanum tuberosum L.) diseases incited by Fusarium spp. include postharvest dry rot and seed-piece decay. Fusarium seed-piece decay is commonly controlled by preplant applications of chemical seed treatments. However, isolates of Fusarium spp. resistant to benzimidazole fungicides have been reported (2,4). In the spring of 2007, samples of cut seed tubers (cvs. Shepody and Russet Burbank) showing extensive symptoms of decay were received from three seedlots in Prince Edward Island (PE) and one seedlot in Saskatchewan (SK), Canada. All seed tubers had been treated with fludioxonil (Maxim Potato Seed Protectant [PSP], 0.5% fludioxonil) following cutting and then stored for 10 to 14 days prior to planting. Using standard isolation protocols (4), the 19 potato tuber pieces examined from PE and 2 from SK yielded 21 Fusarium isolates for further study. Five isolates (including both isolates from SK) were identified as Fusarium sambucinum Fuckel and the remaining 16 isolates were identified as F. coeruleum (Libert) Sacc. (3). To confirm identifications, isolates were compared with two known standards of each of F. sambucinum and F. coeruleum identified by K. Seifert (Agriculture and Agri-Food Canada, Ottawa, ON) by DNA sequencing of the partial β-tubulin gene or the translation elongation factor 1-α ( http://fusarium.cbio.psu.edu ; [1]). These standard isolates were also used as fludioxonil-sensitive controls in amended agar assays for chemical sensitivity. Agar plugs (5 mm in diameter) taken from the margins of 7-day-old cultures of the Fusarium isolates were transferred to petri dishes containing ½-strength potato dextrose agar amended with 0, 0.1, 1.0, 10.0, or 100.0 mg/liter of fludioxonil. Fludioxonil (Maxim PSP, 0.5% a.i.) was prepared as a stock solution in sterile distilled water and added to the molten agar after autoclaving. Culture incubation and mycelial growth measurements were performed as described previously (4). Measurements from four replicate petri dishes per concentration of fludioxonil were taken. Calculated EC 50 values (fludioxonil concentration inhibiting pathogen growth by 50%) were obtained. The trial was repeated three times. The two standard isolates of F. sambucinum were sensitive to fludioxonil, with mean EC 50 values of 0.002 (±0.002 standard error [SE]) and 0.005 (±0.002 SE) mg/liter. The two standard isolates of F. coeruleum were also sensitive to fludioxonil, with mean EC 50 values of 0.17 (±0.005 SE) and 0.19 (± 0.005 SE) mg/liter. All other tested isolates of F. sambucinum and F. coeruleum were resistant to fludioxonil and showed no growth inhibition even at 100 mg of fludioxonil per liter. To our knowledge, this is the first report of resistance to fludioxonil in isolates of Fusarium spp. causing potato seed-piece decay. Since the isolates of F. sambucinum were also resistant to thiophanate-methyl and thiabendazole (data not shown), multiclass (benzimidazole and pyrrole) resistance was also documented. References: (1) D. M. Geiser et al. Eur. J. Plant Pathol. 110:473, 2004. (2) L. M. Kawchuk et al. Am. Potato J. 71:185, 1994. (3) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. Pennsylvania State University Press, 1983. (4) R. D. Peters et al. Plant Dis. 85:1030, 2001.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».