Investigation of emerging diseases of hazelnut cultivars ( <i>Corylus avellana</i> L.) grown in British Columbia, Canada
Bibliographic record
Abstract
Orchards of two- to ten-year-old hazelnut cultivars (Corylus avellana L.) in southwestern British Columbia, Canada, that are resistant to Eastern Filbert Blight were investigated for emerging diseases that had not been reported previously. Eighteen orchards were inspected periodically over three-years and tissues and soil samples from symptomatic trees were analysed for the causal agents. The organisms associated with the symptoms were isolated and identified based on morphological characteristics, followed by PCR and DNA sequencing. The causal agents were confirmed by pathogenicity assessment on detached stem cuttings and in planta. Symptoms related to three major diseases of hazelnut were recognized. Symptoms of ‘flagging’ of stems and ‘dieback’ of branches were associated with two distinct canker diseases. Diaporthe canker caused by Diaporthe eres Nitschke produced elongated, brown to dark brown cankers with tanned yellow margin on stems, and sunken, reddish-brown cankers on tree trunks. Cytospora canker caused by Cytospora rhodophila Sacc. produced elliptical to diamond-shaped, dark brown to reddish-brown cankers that often originated at branching nodes. Diaporthe canker was found to be more prevalent than Cytospora canker. Both cankers often displayed a wedge-shaped browning of internal tissues due to the death of cortex, peridermal and pith tissues. The symptoms of Diaporthe and Cytospora cankers were distinct from the symptoms of eastern filbert blight. Besides the canker diseases, in planta pathogenicity assessment of Pythium dissotocum Drechsler, and Phytophthora taxon hungarica, Phytophthora plurivora T. Jung & T.I. Burgess and Ilyonectria radicicola (Gerlach & L. Nilsson) P. Chaverri & Salgado, isolated from hazelnut trees suspected of root rot, confirmed their ability to cause root rot and chlorosis of leaves on two- and three-year-old hazelnut trees, respectively. The cause for the ‘weeping’ symptoms of oozing sap from tree trunks and scaffold branches was not fully understood and the symptoms could not be attributed to a pathogenic bacterium or fungus. This study confirms that eastern filbert blight-resistant hazelnut cultivars ‘Jefferson’ and ‘Yamhill’ are prone to new diseases that have not been encountered previously in British Columbia.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".