First Published Report of Rust on White Alder Caused by <i>Melampsoridium hiratsukanum</i> in the United States
Bibliographic record
Abstract
White alder (Alnus rhombifolia) is a fast-growing tree native to the western United States and is planted frequently in landscapes. In September 2010, mature leaves of white alder with small, orange-yellow pustules were collected in a commercial nursery in Santa Cruz County, CA. Approximately 25 white alder trees were affected. Collected leaves were sent to the California Department of Food and Agriculture Plant Pest Diagnostics Laboratory. Young uredinial pustules were bullate, with urediniospores emerging from a single pore in the pustule. Spiny cells lined the ostiole. With age, pustules broke open to release more spores. Urediniospores were obovate to oval and measured from 14 to 20 × 27 to 41 μm (17.1 × 32.2 μm average, n = 62). Spores were uniformly echinulate and contained a nearly hyaline cell wall measuring from 1 to 2 μm (1.5 μm average) in thickness. A portion of the 28S ribosomal subunit (GenBank Accession No. KC313888) and the internal transcribed spacer regions (KC313889) were amplified and sequenced from DNA extracted from urediniospores using primers LR6 and rust2inv (1) and ITS1-F and ITS4-B (2), respectively. Our ITS sequence had 99% identity to GenBank accession EF564164, Melampsoridium hiratsukanum. In September 2011, white alder leaves with similar symptoms were collected from a commercial nursery in Santa Barbara County, CA. The spore morphology matched the white alder sample previously collected in Santa Cruz County, CA, in 2010. At that time, pathogenicity assays were conducted on three 1-year-old, 61-cm white alder trees planted in 3.8-liter pots. Six detached leaves with visible rust pustules were rubbed gently onto both the apical and distal side of moistened leaves of the healthy alders. Each infected leaf was used to inoculate a total of 6 to 10 healthy leaves by rubbing two leaves per tree before moving to the next tree. Leaves on three additional white alder trees were rubbed with healthy leaves as controls. Trees were incubated in a dew chamber for 3 days in darkness at 24°C, then placed in a growth chamber at 22°C with a 12-h photoperiod. Twelve days after inoculation, small lesions were visible on a few of the leaf undersides of each inoculated tree. Not all inoculated leaves developed pustules. No lesions developed on the control trees. M. hiratsukanum has been reported in Canada, Europe, and eastern Asia (3). There are no published reports of this rust in the United States, but there is an unpublished specimen from white alder in the USDA Systematic Mycology Herbarium (BPI 028048) collected from California in 1931, which was identified as M. hiratsukanum by G. B. Cummins using morphological criteria. We are unaware if older specimens of this rust exist because we were unable to search other herbaria in the United States. To the best of our knowledge, this rust has been present in California since 1931, but has only recently been found causing disease in nursery plants. There have been no reports of the serious foliar disease symptoms on trees in California wild lands as have been reported in Europe, presumably due to dry summer and fall seasons in white alder's natural habitat. References: (1) M. C. Aime. Mycoscience 47:112, 2006. (2) M. Gardes and T. D. Bruns. Mol. Ecol. 2:113, 1993. (3) J. Hatula et al. Mycologia 101:622, 2009.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".