What attacks willow: pests and diseases the sources name

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 table is on the linked page and is not repeated here. The register is short because the sources read give separate facts for only three agents. Other tree registers are on the poplar and aspen page and the maple page.

The register

Agent	What the sources record
Watermark disease, Brenneria salicis (earlier name Erwinia salicis)	Kind: Bacterial disease Hosts: The University of East Anglia abstract says it affects six species of tree willow, with white willow (Salix alba) and some of its varieties particularly susceptible, and that it causes severe losses in the cricket bat willow (S. alba var. caerulea) and in several Dutch white willow clones. The Woodland Trust says white willow and crack willow are susceptible, and that over time affected branches die back and red leaves develop in the crown. It says the tree can die. The Woodland Trust describes the cricket bat willow as a hybrid of white willow and crack willow whose strong wood suits cricket bats. Where and status: The University of East Anglia abstract says the disease was first reported in 1924. No regulated status is given on the pages read. How it lives in the tree: The abstract says that unusually for a bacterial disease the bacterium lives only in the water-carrying wood (xylem), which becomes discoloured. A study in the Czech journal Plant Protection Science found the bacterium in the wood of healthy willows as well as diseased ones, with its concentration rising and falling with the season, high when water stagnates in the wood in winter and drawn out towards the leaves by the sap stream in active trees. The authors concluded that disease risk cannot be assessed by testing for the bacterium.
Cytospora canker, Cytospora chrysosperma. Full profile	Kind: Weak and opportunistic fungus Hosts: Natural Resources Canada says the main hosts in Canada are poplar and willow, and that the disease does not occur on healthy, vigorous branches or trunks. Where and status: Found worldwide. No regulated status is given.
Asian longhorned beetle, Anoplophora glabripennis. Full profile	Kind: Wood-boring beetle Hosts: The Canadian Food Inspection Agency calls it a highly destructive wood-boring pest of maples and other hardwoods including poplar, birch and willow. Where and status: The Canadian agency says the beetle can kill trees directly or indirectly by enabling other pests and diseases, and asks for reports of it.

What the sources say about the tree

The Woodland Trust says white willow is the largest willow, with mature trees up to 25 m, and that like most willows it grows in wet ground such as river and stream sides. It records caterpillars of the puss moth, willow ermine, eyed hawk-moth and red underwing feeding on white willow leaves, and catkins as an early source of nectar and pollen. It does not call these a threat to the tree.

Who the sources say to report to

The Canadian Food Inspection Agency asks that Asian longhorned beetle or signs of it be reported. The offices for each country are on the report a pest in Canada and report a pest in the United Kingdom pages. The pages read for watermark disease and Cytospora canker name no report line.

What attacks willow: pests and diseases the sources name

The register

What the sources say about the tree

Who the sources say to report to

Sources