First Report of Pineapple Black Rot Caused by <i>Ceratocystis paradoxa</i> on <i>Ananas comosus</i> in French Guiana
Bibliographic record
Abstract
Ceratocystis paradoxa (Dade) C. Moreau is a polyphagous wound parasite causing black rot post-harvest disease in pineapple. This fungus is responsible for high losses of fruit destined for the fresh market and is a common problem in many countries (2). C. paradoxa is officially listed as a quarantine pathogen for French Guiana. In November 2013, the Plant Protection Service of French Guiana observed damage in crops of Ananas comosus var. perolera located in Corossony (4°19'10.8″ N, 52°10'17.1″ W) and Wayabo (5°01'02.3″ N, 52°36'18.7″ W) (eastern and middle part of the country). The three plants collected at each location showed a soft base rot of the stem and of young leaves, and developed a foul smell. Plant tissues were collected from the edge of the lesions, chopped in small pieces, and plated on malt extract agar supplemented with 100 ppm chloramphenicol. The plates were incubated at 25°C with a 12-h photoperiod. After 5 days, a fungal colony, first white and downy, then becoming black and velvety after 10 days, was transferred on potato dextrose agar (PDA) and incubated in the same conditions. After 7 days, the colonies produced phialides releasing cylindrical or doliform conidia that were unicellular, colorless to pale brown, in long chains (3.09 to 20.17 × 3.1 to 5.57 μm, n = 20) and oval, pyriform, brown chlamydospores (8.02 to 21.32 × 4.20 to 9.76 μm, n = 20), occurring in long chains or singly with a vertical slit, usually not very visible. Furthermore, the colonies emitted a fruity odor. On the basis of these morphological characteristics, the fungus was identified as the anamorph of C. paradoxa (Thielaviopsis paradoxa (De Seynes) Höhn.) (1). The species designation was confirmed by sequencing the ITS region of the rDNA followed by comparison with reference sequences available in GenBank. Fungal material was collected from PDA culture by scraping the mycelium with a sterile needle and transferring into 2-ml microtubes. Fungal total DNA was then extracted and the ITS region was amplified by PCR using the ITS1-ITS4 primer pair. Nucleotide sequence was determined and deposited in GenBank (KJ667047). BLAST analysis showed 100% identity with C. paradoxa. The pathogenicity of the fungus was confirmed by inoculating two pineapples with mycelium from the C. paradoxa isolate grown on PDA. The peel of fruits and the base of the crowns were wounded with a sterile scalpel blade, each at five locations. Mycelial plugs (avg. 4 mm diameter) were placed on the wounds. Inoculation sites were wrapped with Parafilm to prevent dehydration and to hold the mycelial plugs in position. Negative controls received five sterile PDA plugs. The samples were incubated at 25°C in a moist chamber with a 12-h photoperiod. Eight days after inoculation, negative controls remained symptomless, whereas characteristic soft, watery, and black rot lesions developed on the base of all the crowns that were inoculated with C. paradoxa. The pathogen was successfully re-isolated from symptomatic tissues, fulfilling Koch's postulate. To our knowledge, this is the first report of C. paradoxa on A. comosus in French Guiana, and quarantine measures have been enforced to prevent the spread of this pathogen that might also cause severe losses on other susceptible plant species that are important for the local market (e.g., banana, coconut, sugar cane). Pineapple has become a major crop in French Guiana, and is now subjected to a more intensive monitoring, which may explains why this disease was discovered recently. References: (1) T. R. Nag Raj and W. B. Kendrick. A Monograph of Chalara and Allied Genera. Wilfrid Laurier University Press, Waterloo, Ontario, 1975. (2) R. C. Ploetz et al., eds. Compendium of Tropical Fruit Diseases. American Phytopathological Society, St. Paul, MN, 1994.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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 source (direct Gemma or distilled Codex), 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".