First Report of <i>Erysiphe palczewskii</i> Powdery Mildew of Siberian Pea Tree (<i>Caragana arborescens</i>) in Wisconsin and Quebec
Notice bibliographique
Résumé
Shoots affected by powdery mildew were collected from Siberian pea trees in July 2009 on the University of Wisconsin-Madison campus and on the campus of Université Laval, Quebec City, Quebec. This exotic shrub or small tree is infrequently planted in Wisconsin and three shrubs in a group that were affected are the only examples known on the UW-Madison campus. In Quebec City, Siberian pea tree is more commonly used as an ornamental, often in hedges (as is the case of the affected plants on the Université Laval campus). In both locations, <10% of foliage was visibly affected, but incidence was greater on shoots closer to the ground than on higher shoots. White-to-grayish mycelium was present on leaves and young stems and sometimes completely covered both upper and lower leaf surfaces. Dark brown-to-black chasmothecia were numerous on leaf blades, petioles, and young stems, but were most abundant on lower surfaces of leaves. Morphology of chasmothecia, including appendages with distinctive terminal dichotomous branching, (1) was consistent with descriptions and illustrations of the fungus Erysiphe palczewskii Jacz. (synonym Microsphaera palczewskii) (1-4) thought to be native to Asia, but also known as an invader of Europe where it occurs on the same host. For a sample from Université Laval, mean diameter of chasmothecia was 113 μm, mean appendage length was 185 μm, and barrel-shaped conidia that lacked fibrosin bodies averaged 30 × 14 μm. Asci contained oval, yellow ascospores with mean dimensions of 20 × 12 μm. DNA was extracted from chasmothecia, and nuclear rDNA sequences (633 nucleotides) of the Wisconsin (GenBank Accession No. GQ497277) and Quebec (GenBank Accession No. GQ497276) specimens differed by only one nucleotide. The sequences that were obtained most closely matched GenBank sequences for Oidium spp. (98%) and Erysiphe spp. (97%). Further observations indicated that the same pathogen affected Siberian pea trees planted as ornamentals at several locations separated by ≥15 km in the metropolitan Quebec area. This report extends the eastern known limit of E. palczewskii in the United States, previously known from collections in Alaska (2), Washington (4), Idaho (4), North Dakota (3), and Minnesota (3). To our knowledge, this is the first report of this disease in Canada, and it indicates that the distribution of E. palczewskii is transcontinental. Specimens from Madison, WI and Quebec, QC have been deposited in the U.S. National Fungus Collections (BPI 879152) and the Rene Pomerleau Herbarium of the Canadian Forest Service Laurentian Forestry Centre (QFB-22601). References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) D. A. Glawe and G. A. Laursen. Online publication. doi:10:1094/PHP-2005-1017-01-BR. Plant Health Progress, 2005. (3) D. A. Glawe et al. Online publication. doi:10.1094/PHP-2006-0117-01-BR. Plant Health Progress, 2006. (4) C. Nischwitz and G. Newcombe. Plant Dis. 87:451, 2003.
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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 ».