A study of Aphanomyces euteiches Drechs. root rot of field pea (Pisum sativum L.) in Manitoba
Notice bibliographique
Résumé
Aphanomyces euteiches Drechs. is an important yield reducing pathogen of field pea (Pisum sativum L.) in Manitoba. Currently, disease control is achieved through crop rotation or avoidance of fields with high inoculum pressure. The purpose of this study was to determine A. euteiches incidence, pathogenicity and host-range, as well as the effect that fungicidal and biological seed treatments have on pathogen control. A survey of commercial field peas was conducted in 1999 and 2000 to determine the incidence of A. euteiches in Manitoba. Aphanomyces euteiches was isolated from 9 of 44 fields surveyed. The Aphanomyces isolates originated from fields within a 400 km range extending from Morden to Russell, Manitoba. Growth cabinet experiments were carried out in 2000 and 2001, to determine if certain environmental conditions and hosts were favourable to the pathogen. Using the pea variety Carneval, seven A. euteiches isolates (15,22,24,25,26,27 and 41) were studied at four growing temperatures (16,20,24, and 28o C) and three seedling ages (1,2, and 3 weeks). Measurement to determine the extent of disease development included disease severity and root and shoot dry weights. Disease development was favourable at all four temperature regimes tested. Seedling age had no consistent effect on disease development. Disease severity between the seven A. euteiches isolates were significantly different (p=0.05), suggesting that pathogenic variability exists between the isolates of A. euteiches. To determine each isolates host-range, all seven isolates were tested against four pea varieties (AC Tamor, Carneval, Marjoret, and Trapper), eight lentil varieties (CDC Glamis, CDC Robin, Crimson, Eston, French, Indianhead, Laird, and Richlea), two chickpea varieties (CDC Desiray and CDC Yuma), six bean varieties (AC Clack Diamond, CDC Pintium, AC Scarlet, Envoy, Navigator, and Pintoba), one Alfalfa variety (OAC Minto) and one soybean variety (Alta). All seven isolates were virulent on the four pea varieties tested and avirulent on the soybean, chickpea and bean varieties tested. Lentil and alfalfa were the only hosts to with both susceptible and resistant lines to the seven isolates. Field experiments to determine the effect of seed applied fungicides and biological agents on pathogen control were conducted in 1999 and 2000 at sites in and near Morden and in Winnipeg, Manitoba. A natural source of inoculum was relied upon at each location. The thirteen fungicide and biological seed treatments tested included seven fungicides (Aliette, Apron, Crown, Ridomil, Ronilan, Thiram, and Vitaflo-280) and two biological agents (ACM941 and AR101). Three combination treatments were also tested, consisting of both a fungicide and a biological agent (ACM941+Aliette, ACM941+Apron and ACM941+Vitaflo-280). Emergence, disease severity, root and shoot dry weights and yield were measured to determine the effect each treatment had on Aphanomyces root rot. Emergence was significant (p=0.05) at each field site, although the overall effect that individual treatments had on emergence varied between sites. Average disease severity and yield ranged from 0.3 to 3.9 and 467g to 1227g between sites, respectively. These differences may have resulted from variable environmental conditions (temperature, moisture and soil type) between sites and years, and/or the relative aggressiveness of the A. euteiches isolates present. An increase in inoculum pressure, resulting from growing the same crop in consecutive years could also explain the increase in disease severity. These results suggest that A. euteiches is more extensively spread in Manitoba than previously believed and that the isolates present are pathogenically variable. The importance of crop rotation as a method of controlling this disease is also evident since pea, lentil and alfalfa were obvious hosts and none of the thirteen seed treatments tested significantly controlled A. euteiches root rot of field pea.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| 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 | 0,001 | 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) | 0,001 | 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 source (Gemma direct ou Codex distillé), 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 ».