First report of <i>Verticillium dahliae</i> race 2 in Tunisia
Notice bibliographique
Résumé
Vascular wilt diseases have recently become a serious problem on tomato (Lycopersicon esculentum) throughout the Tunisian Sahel. Since 2002, plants of cv. Colibri with symptoms characteristic of Verticillium infection (wilting, yellowing, stunting and dark brown vascular discoloration) have been seen in many greenhouses in the Chott Mariem region. Isolates from diseased plants were identified as Verticillium dahliae on the basis of microsclerotium production (Hawksworth & Talboys, 1970). Cultivar Colibri carries a single dominant gene (Ve) conferring resistance to race 1 of V. dahliae (Schaible et al., 1951). This resistance has been effective for over 20 years. Wilt caused by V. dahliae has also been confirmed in several other resistant cultivars (e.g. Amel, Cenkara, Rio Grande). Fifty-one Tunisian isolates were tested to determine their race, with Canadian and Israeli race 1 and 2 isolates (one each) included as controls. Conidial suspensions of 107 conidia mL−1 were used to inoculate plants of the cvs Ventura and Sun 6200 (susceptible to both races), and Rio Grande, Colibri and Naya (resistant to race 1), at the two-leaf stage by root dipping. Seedlings were replanted into a sterile 2:1 mixture of peat/perlite (v/v) and maintained in a growth chamber at 23 ± 3°C. Equal numbers of plants of each cultivar were dipped into water as controls. The experimental design was a completely randomized type with ten replicates (pots). Tests were conducted twice. Susceptible plants developed typical symptoms of wilt as above, starting two to three weeks after inoculation, followed by plant death. Race 1 isolates gave either no or only very mild symptoms in the resistant cultivars. Control plants showed no symptoms. In cultivars where infection occurred, most plants developed typical symptoms. V. dahliae was recovered by in vitro isolation and incubation from all plants with symptoms. Based on the differential reactions of the five cultivars, 10 isolates were classified as race 1 and 41 as race 2. The appearance of V. dahliae race 2 in tomatoes in Tunisia poses a major threat to this crop, particularly in protected cultivation where no rotations are used and the absence of soil disinfection favours the build-up of soil-borne inoculum. Race 2 has been reported from southern Europe, North and South America and North and South Africa (Pegg & Brady, 2002), but this is the first report from Tunisia. The authors would like to thank Aymen Youssef for his excellent technical assistance.
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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.
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| Catégorie | Codex | Gemma |
|---|---|---|
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| 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.
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