First Report of Beech Leaf Disease Caused by the Foliar Nematode Litylenchus crenatae on American Beech in North Carolina

Beech leaf disease (BLD) is a newly emergent and potentially lethal condition of beech trees (Fagus spp.) in North America, caused by the foliar nematode, Litylenchus crenatae (Lc) (Carta et al. 2020; Wolf and Vieira 2026). Disease spread has been rapid and several times complicated by new infestations found at great distances from known sites (Kantor et al., 2022). The characteristic disease symptoms on the host are readily recognized, which allows for early identification of recently infested trees based on visual indicators. In late summer of 2025, Gangloff, W. (second author) used iNaturalist to observe BLD-suspected symptoms in American beech (F. grandifolia Ehrh.) on the outskirts of Boone, NC (Watauga County). To verify his iNaturalist report, a site visit was conducted in the autumn and found banding symptoms typical of BLD in the retained leaves and leaf litter of the stand, which consisted of mixed American beech and rhododendron shrubs growing on a natural wooded slope. We collected twigs bearing buds adjacent to symptomatic marcescent foliage. Dissection and nematode extraction at the Bartlett Tree Research Laboratories revealed characteristic enlarged, asymmetrical cells at the base of bud scales (Wolf and Vieira, 2024), as well as presence of active Lc nematodes within the buds. DNA was extracted from nematodes and infested plant tissue using the Qiagen Plant Pro Kit and molecular analysis confirmed the identity of Lc. For official confirmation and to validate morphological identification and disease symptomatology, a portion of the sample was sent to the Nematode Assay Section, North Carolina Department of Agriculture & Consumer Services, for sequence analysis. Additional PCR and DNA sequencing on the 18S small subunit ribosomal DNA (GenBank accession number: PZ574936), internal transcribed spacer 1 and 2 (PZ574941) and the 28S large subunit ribosomal DNA (PZ574942) were performed and revealed 100% similarity to sequences of Lc from GenBank (MK292138, MN525397). To capture a full disease cycle, we returned to the site in May of 2026 to observe the beech trees at full leaf expansion. The stand displayed progressed BLD symptom severity, with one mature beech exhibiting nearly 50% canopy thinning, and surrounding beech showing widespread leaf banding and distortion. Several additional groups of naturally occurring American beech in the vicinity (about 300 ft away) were also found to be symptomatic with banding symptoms, demonstrating local spread. To our knowledge, this is the first report of this nematode species in conjunction with F. grandifolia expressing BLD symptoms in North Carolina. This marks a new southernmost confirmation of BLD in North America, information valuable for modeling of climate and disease dynamics. Furthermore, it highlights the risk of long-distance jumps in distribution. This site in Boone, NC is approximately 200 miles south and southwest, respectively, from the two nearest confirmed counties with BLD: Washington Co., OH and Albemarle Co., VA. Lastly, this report demonstrates the valuable contributions of citizen scientists in early detection of invasive plant pathogen spread.