EPPO Alert List – Litylenchus crenatae mccannii and beech leaf disease
A new disease of beech trees (Fagus spp.) called 'Beech leaf disease' (BLD) has increasingly been observed in forest areas in Eastern USA and Canada (EPPO RS
EPPO region: Absent.
North America: Canada (Ontario), USA (Connecticut, Maine, Massachusetts, Michigan, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Virginia, West Virginia).
On which plants
BLD mainly affects F. grandifolia (American beech). However, it was also observed in 2016 on F. sylvatica (European beech) and F. orientalis (Oriental beech) in a tree collection (Holden Forests and Gardens in Geauga county, Ohio), as well as in 2017 on F. sylvatica in commercial nursery stock (Lake county, Ohio). F. engleriana (Chinese beech) is considered to be a potential host.
Early symptoms of BLD include dark-green striped bands between lateral veins of leaves and reduced leaf size. Banded areas usually become leathery-like, and leaf curling is also observed. As symptoms progress, aborted buds, reduced leaf production, and premature leaf drop lead to an overall reduction in canopy cover, ultimately resulting in death of sapling-sized trees within 2-5 years and of large trees within 6 years. In areas where the disease is established, the proportion of symptomatic trees can reach more than 90%. However, it is noted that some variability in susceptibility has been observed among beech trees.
Pictures of symptoms observed can be viewed on the Internet: http://forestry.ohiodnr.gov/portals/forestry/pdfs/BLDAlert.pdf
If L. crenatae mccannii is the main cause of BLD, plants for planting and cut foliage could be potential pathways for long distance transport. However, how the nematode spreads among forest trees is currently unknown. In particular, it is not known whether the nematode can survive in other plant parts or in the soil during winter after beech leaves have fallen.
Plants for planting, cut branches of Fagus spp. from countries where the disease occurs?
Fagus spp. are widely planted in the EPPO region for forestry and amenity purposes. In particular, F. sylvatica is an important deciduous forest tree in Western and Central Europe (e.g. used for wood production). Many aspects remain to be clarified, in particular, it is still unclear whether L. crenatae mccannii plays a role in BLD or if the disease is associated with a complex of pathogens (e.g. fungi, bacteria, viruses or phytoplasmas). If L. crenatae mccannii is asociated with BLD, its biology and epidemiology also need to be further studied to better assess its potential risk. However, considering, the rapidity of spread and the severity of damage (i.e. tree decline and mortality) observed on Fagus species in North America, it was felt that the attention of NPPOs should be drawn to this emerging disease and the potential risks it may present to the forestry and ornamental sectors of the EPPO region.
Burke DJ, Hoke AJ, Koch J (2020) The emergence of beech leaf disease in Ohio: probing the plant microbiome in the search of the cause. Forest Pathology, e12580. https://doi.org/10.1111/efp.12579
Carta LK, Handoo ZA, Li S, Kantor M, Bauchan G, McCann D, Gabriel CK, Yu Q, Reed S, Koch J, Martin D, Burke DJ (2020) Beech leaf disease symptoms caused by newly recognized nematode subspecies Litylenchus crenatae mccannii (Anguinata) described from Fagus grandifolia in North America. Forest Pathology, e12580. https://doi.org/10.1111/efp.12580
Ewing CJ, Hausman CE, Pogacnik J, Slot J, Bonello P (2018) Beech leaf disease: an emerging forest epidemic. Forest Pathology e12488. DOI: 10.1111/efp.12488
- Center for Invasive Species Prevention (2018-05-17) Invasive Species. Update on Beech Leaf Disease, a threat lacking adequate funding and official action. http://www.nivemnic.us/update-on-beech-leaf-disease-a-threat-lacking-adequate-funding-and-official-action/
- Central Pennsylvania Forestry (2018-03-08) Look for Beech Leaf Disease. http://centralpaforest.blogspot.com/2018/03/look-for-beech-leaf-disease.html
- Don’t move firewood. Beech leaf disease. https://www.dontmovefirewood.org/pest_pathogen/beech-leaf-disease/
- Government of Massachusetts. Mass.gov (undated) Beech Leaf Disease in Massachusetts. https://www.mass.gov/guides/beech-leaf-disease-in-massachusetts
- Government of Michigan. Michigan.gov (2022-07) Invasive species: beech leaf disease. https://www.michigan.gov/invasives/id-report/disease/beech-leaf-disease and Invasive beech leaf disease found in Michigan. https://www.michigan.gov/invasives/news/2022/07/05/invasive-beech-leaf-disease-found-in-michigan
- Government of Rhode Island. RI.gov. Press Release (2020-07-13) DEM asks public to be aware of Beech Leaf Disease. https://www.ri.gov/press/view/38824
- Government of Rhode Island. RI.gov. Press Release (2023-06-22) Beech leaf disease is widespread in Rhode Island: DEM no longer requests reports. https://dem.ri.gov/press-releases/beech-leaf-disease-widespread-rhode-island-dem-no-longer-requests-reports
- Lake Metroparks. Beech leaf disease. A new problem to our forests by J. Pogacnik (2018-08-14). https://www.lakemetroparks.com/along-the-trail/august-2018/beech-leaf-disease
- Maine Department of Agriculture, Conservation & Forestry (2021-06-07) Beech leaf disease added to Maine’s invasive species list. https://www.maine.gov/dacf/mfs/news-article.html?id=4882869
- Ohio Department of Natural Resources Forestry Division (2018-08-20) ODNR urges Ohioans to report Beech Leaf Disease. http://forestry.ohiodnr.gov/news/post/odnr-urges-ohioans-to-report-beech-leaf-disease
- USDA. We need your help. Look for signs of Beech Leaf Disease. http://files.constantcontact.com/3eb6bf61101/a51df273-005c-4330-88eb-e4ea5294ea0d.pdf
- USDA National Invasive Species Information Center. What’s New. https://www.invasivespeciesinfo.gov/whats-new
Kantor M, Handoo Z, Carta L, Li S (2021) First report of beech leaf disease, caused by Litylenchus crenatae mccannii, on American beech (Fagus grandifolia) in Virginia. Plant Disease (first view). https://doi.org/10.1094/PDIS-08-21-1713-PDN
Kanzaki N, Ichihara Y, Aikawa T, Ekino T, Masuya H (2019) Litylenchus crenatae n. sp. (Tylenchomorpha: Anguinidae), a leaf gall nematode parasitizing Fagus crenata Blume. Nematology 21(1), 5-22. DOI: https://doi.org/10.1163/15685411-00003190
Marra RE, LaMondia J (2020) First report of beech leaf disease, caused by the foliar nematode, Litylenchus crenatae mccannii, on American beech (Fagus grandifolia) in Connecticut. Plant Disease (early view). https://doi.org/10.1094/PDIS-02-20-0442-PDN
Martin DK, Volk D (2021-01) Pest Alert. Beech Leaf Disease. USDA, Forest Service. Eastern Region State and Private Forestry (R9–PR–001–21), 2 pp. http://www.dontmovefirewood.org/wp-content/uploads/2019/02/Beech-Leaf-Disease-Pest-Alert.pdf
Pogacnik J, Macy T (2016-07) Forest Health Pest Alert. Beech Leaf Disease. http://forestry.ohiodnr.gov/portals/forestry/pdfs/BLDAlert.pdf
Reed SE, Greifenhagen S, Yu Q, Hoke A, Burke DJ, Carta LK, Handoo ZA, Kantor MR, Koch J (2020) Foliar nematode, Litylenchus crenatae ssp. mccannii, population dynamics in leaves and buds of beech leaf disease-affected trees in Canada and the US. Forest Pathology 50, e12599.