What attacks poplar and aspen: pests and diseases the sources name
A register of the canker fungus, the leaf rusts, the stem rot, the bacterial canker and the longhorned beetle that Canadian and British sources tie to poplar and aspen: which trees each page names, where each is recorded, the season each source mentions, and where the full profile is.
Checked against the sources at the bottom of this page on October 9, 2026. Rules, fees and pay change: the source has the last word.
This page reports what the named sources say. It is not a diagnosis of any tree and does not say what should be done with one. Each row names its source, all read on October 9, 2026. Where this site has a full profile, the row links it, and the regulated status tables are on the linked pages and are not repeated here. Poplars and aspen are covered species by species in tree species in the agency records, including balsam poplar, eastern cottonwood and black cottonwood, and the European aspen is on the aspen page.
The register
| Agent | What the sources record |
|---|---|
| Cytospora canker, Cytospora chrysosperma. Full profile | Kind: Fungus; Natural Resources Canada calls it a weak and opportunistic pathogen Hosts: Natural Resources Canada says the main hosts in Canada are poplar and willow, with reports on maple, alder, birch, dogwood, hawthorn, apple, cherry, plum and others, and over two hundred host species worldwide. It says the disease does not occur on healthy, vigorous branches or trunks, and its presence indicates underlying stress such as drought, repeated defoliation, frost or sun damage. Where and status: Found worldwide. Natural Resources Canada lists reports from seven provinces: Alberta, British Columbia, Manitoba, Nova Scotia, Ontario, Quebec and Saskatchewan. No regulated status is given. Season: Natural Resources Canada says the callus a tree forms at the canker edge each growing season is overcome by the fungus while the tree is dormant in winter, which makes concentric target rings. Spore tendrils are pushed out during periods of high humidity. |
| Aspen leaf rusts, Melampsora species, and stem rot, Phellinus tremulae | Kind: Rust fungi and a decay fungus Hosts: Forest Research says aspen can be attacked by leaf rusts that can result in serious defoliation, and that older and larger trees can be killed by the stem rot. Where and status: Britain, in the species entry. No regulated status is given. Season: No season given on the page read. |
| Bacterial canker of aspen | Kind: Bacterial disease Hosts: Forest Research says it can seriously damage certain clones of aspen. It names no bacterium on the page read. Where and status: Britain, in the species entry. No regulated status is given. Season: No season given on the page read. |
| Asian longhorned beetle, Anoplophora glabripennis. Full profile | Kind: Wood-boring beetle Hosts: The Canadian Food Inspection Agency says poplar, birch and willow are occasionally affected, with maple the group most likely to be affected. Forest Research lists poplar (Populus) among known hosts. Where and status: The Canadian agency says it was eradicated from Mississauga and Toronto in 2020. Forest Research lists it as not present in the United Kingdom and notifiable. Season: No season given on the pages read for poplar. |
How the sources describe the effects
Natural Resources Canada says Cytospora canker can cause significant losses in stool beds, which are tight rows of coppiced trees cultivated to produce shoots for cuttings, and in new plantations planted with those cuttings. There the symptom is called black stem, from the blackening of inner tissues seen through thin bark. On established trees it describes spreading bark necrosis, localised lesions or perennial target cankers, with the early stage on smooth aspen bark showing as orange or brown. Forest Research ties the aspen rusts to defoliation and the stem rot to death of older trees, and says certain clones can be seriously damaged by bacterial canker. The Canadian Food Inspection Agency calls the Asian longhorned beetle highly destructive, with larvae that can kill trees directly or indirectly by enabling other pests and diseases.
Profiles on this site
The full profiles linked in the table are Cytospora canker and Asian longhorned beetle. The leaf rusts, stem rot and bacterial canker have only the rows above, because the page read gives too few separate facts for a page each. A second register with the same beetle is on the maple page.
Who the sources say to report to
The Canadian Food Inspection Agency asks that Asian longhorned beetle or signs of it be reported to the agency immediately. Forest Research lists the beetle as notifiable in the United Kingdom, where suspected cases go through TreeAlert. The pages read for the canker, rusts and stem rot name no report line. The reporting offices for each country are on the report a pest in Canada and report a pest in the United Kingdom pages.
Sources
- Natural Resources Canada, Cytospora canker fact sheet (revision 2024), read October 9, 2026
- Forest Research, tree species database entry for aspen (ASP), adapted under the Open Government Licence v3.0, read October 9, 2026
- Canadian Food Inspection Agency, Asian longhorned beetle page (modified September 4, 2025), read October 9, 2026
- Forest Research, Asian longhorn beetle (Anoplophora glabripennis) page, adapted under the Open Government Licence v3.0, read October 9, 2026