First report of <i>Verticillium dahliae</i> race 2 in Tunisia
Bibliographic record
Abstract
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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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".