First Report of Halo Blight on Hop (<i>Humulus lupulus</i>) Caused by <i>Diaporthe humulicola</i> in Minnesota
Notice bibliographique
Résumé
Halo blight, caused by Diaporthe humulicola, is an emerging issue in hop production in the Upper Midwestern and Eastern North America. Reports of halo blight thus far have included Connecticut, Michigan, New York, and Quebec (Allan-Perkins et al.; Hatlen et al. 2022; Higgins et al. 2021; Sharma et al. 2022). In August 2020, brownish-gray necrotic foliar lesions and damaged cones were observed in an experimental hopyard consisting of a breeding population of hop plants grown at the University of Minnesota - Southern Research and Outreach Center in Waseca, MN. The foliar lesions consisted of necrotic concentric circles with some possessing chlorotic halos. Damage to the cones often appeared as reddish brown as bands around cone midsections, scattered on bracts and bracteoles, and in severe cases near entire cones. Disease incidence within the experimental hopyard was observed on >50% of hop plants. No pycnidia were observed on leaves or cones following collection of samples. A total of eleven samples were obtained from diseased leaves or cones. Symptomatic plant tissue was surface-sterilized and sections excised from the leading edge of lesions were plated onto potato dextrose agar (PDA). Fungal growth was hyphal tipped and incubated at 22° C under a 12-h photoperiod for a period of 21 days (Hatlen et al 2022). Culture characteristics on PDA included raised white to light gray mycelium with irregular pycnidia distribution over the surface. DNA was extracted from mycelia using the MagMAX Plant DNA Isolation Kit (Applied Biosystems, Foster City, CA). A representative isolate (M4N) was selected for DNA amplification and bi-directional Sanger sequencing using the following primers ITS1/ITS4 (ITS) for the internal transcribed spacer, CYLH3F/H3-1b for histone 3 (HIS), and Ef1728f/EF1-986R for translation elongation factor 1-α (TEF) (Carbone and Kohn 1999; Glass and Donaldson 1995; White et al. 1990). Following amplification and sequencing, reads were trimmed and assembled using Geneious Prime (Biomatters, New Zealand). BLASTn analysis revealed that the ITS (GenBank Accession OQ144379), HIS (GenBank Accession OQ256246), and TEF (GenBank Accession OQ256245) were 99 - 100% identical to D. humulicola sequences (MN152927, MN180213, MN180207) infecting hop in other US regions (Allan-Perkins et al. 2019; Hatlen et al. 2022). To complete Koch's postulates, two sets each of six 3-month old plants of the hop cv. 'Chinook' were inoculated with either 50 mL of conidial suspension (6 x 105 conidia/mL) derived from pycnidia harvested from 28-day old cultures or with water as a negative control. Following inoculation, plants were then grown in a greenhouse at 100% relative humidity at 22°C with a 14-h photoperiod. Light brown lesions with concentric circles appeared on the adaxial side of the leaf after 3 weeks but were not observed on mock-inoculated plants. We subsequently re-isolated D. humulicola from 100% of infected leaves which was identified based upon colony and conidial morphology using descriptions from Higgins et al. (2021). alpha-conidia (n = 20) averaged 10.96 µm ± 1.12 in length and 5.11 µm ± 0.67 in width, were unicellular and hyaline. No beta-conidia were observed, consistent with previous reports of this pathogen. No disease symptoms appeared on mock-inoculated plants, and D. humulicola was not recovered from mock-inoculated plants. There is significant concern regarding the increasing prevalence of D. humulicola as an emerging pathogen affecting hop production across the Midwestern and Great Lakes region of North America. Future research is needed to determine differences in hop varietal susceptibility and fungicide efficacy for management of this disease.
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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 ».