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Poplar Bacterial Canker


Poplar Bacterial Canker

Usually appear in

All Year

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Caused By:-     The Bacteria Xanthomonas populi


Most poplar cankers are caused by fungi. Poplars are attacked by several different types of canker. Poplar Bacterial Canker is caused by the bacteria Xanthomonas populi, but another bacteria Pseudomonas syringae pv. syringae may also attack poplars. Initial symptom is small cracks in bark of one-year-old shoots, which ooze a dense creamy slime in spring. Cankers may expand to girdle smaller shoots which wilt and die. On larger stems, irregular-shaped lesions break through the bark. Infected leaves may blacken. Most plant pathogens are unable to penetrate bark directly but will quickly colonise wounded tissue.
Pseudomonas and Xanthomonas can only be distinguished with certainty by lab analysis and is spread by infected tools, sap feeding insects or contact through water splashes.
Fungal pores are produced in fruiting bodies on old cankers. The spores can be produced all year round and are wind-dispersed over relatively large distances. Picture by UK Forestry Commission Archive,
See these other Cankers Apple and Pear, Bacterial, Bleeding, Canker, Cytospora, European, Horse Chestnut Bleeding, Mulberry, Parsnip, Pear and Apple, Phomopsis, Rose Stem and Dieback, Willow Black.


Good husbandry and cleaning pruning tools between use and pruning out cankers as soon as they appear is the best way to protect trees as fungicides and bactericides are usually ineffective. Old cankers also spread the disease to other trees.

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