First Report of <i>Verticillium dahliae</i> Causing Wilt in Pumpkin in Trinidad
Notice bibliographique
Résumé
Pumpkin (Cucurbita pepo L.) is an economically important crop in Trinidad. Production supplies local and export markets in Barbados, Antigua and Barbuda, Canada, the United States, and the United Kingdom. However, there has been a marked decline in pumpkin export over the last 3 years. Field infections and development of disease in transit have been identified as major factors in decreased export. Between November 2006 and December 2007 (day/night temperatures of 32 to 34°C and 25 to 27°C, respectively), symptoms of vascular wilt were observed in at least 17 pumpkin fields. Symptoms included discoloration (yellowing with subsequent browning) of the older leaves and stems followed by wilting, girdling, and dieback of vines prior to fruit maturity. Necrotic leaves remained attached to the stems. A light brown vascular discoloration in the absence of a sticky exudate was observed in the stems. Onset of symptoms was most apparent at the late flowering to early fruit development stage. All C. pepo lines appeared equally affected by the disease. Yield losses (reduction of fresh weight and proportion of immature fruits at harvest time) as a result of this disease were estimated at 30 to 80%. Accurate diagnosis and pathogen identification were based on symptomology, colony morphology on potato dextrose agar (PDA) and semiselective media (including presence of microsclerotia), pathogenicity tests, and molecular characterization of the rDNA region. Pathogenicity tests with five isolates (randomly selected but geographically distinct) were conducted on healthy pumpkin plants at the two-true-leaf stage. A spore suspension of 2.1 × 106 conidia/ml was used to inoculate eight seedlings grown in sterile potting mix (1). Plants inoculated with sterile distilled water served as negative controls. Plants inoculated with the spore suspension developed a vascular wilt and general decline 35 days postinoculation. The pathogen was reisolated from all inoculated pumpkin seedlings. Pathogenicity tests were repeated once. Colony morphology consistently conformed to established criteria for Verticillium dahliae (Kleb.) (2). PCR amplification with universal primers ITS4 and ITS5 (3) was carried out on fungal DNA extracted from pure cultures. Sequence comparison of amplicons of approximately 600 bp long (GenBank Accession No. EF377335) was carried out using MEGABLAST search ( www.ncbi.nlm.nih.gov/blast/ ) for highly similar sequences and Lasergene v7.2 (DNASTAR Inc. Madison, WI) software. Alignment data revealed the highest and most significant homology to Verticillium dahliae (GenBank Accession No. DQ282123) at 98.2%. V. dahliae has a wide host range and causes vascular wilt in a large number of economically important crops (2). Control strategies are complicated by the ability of the microsclerotia produced by V. dahliae to survive for more than a decade in soil despite the absence of a host (4). To my knowledge, this is the first report of Verticillium wilt affecting pumpkin in Trinidad. References: (1) S. T. Koike et al. Plant Dis. 78:1116, 1994. (2) G. F. Pegg. Phytopathol. Mediterr. 23:176, 1984. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990. (4) S. Wilhelm. Phytopathology. 45:180, 1955.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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 | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 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 ».