Willow anthracnose, scab and canker

Three important diseases of willows in the UK are anthracnose, scab and black canker. They harm the trees and can make them unsightly.

Willow anthracnose, scab and canker

Quick facts

Common name Willow anthracnose, scab and black canker
Scientific name Drepanopeziza sphaerioides, Venturia saliciperda and Glomerella miyabeana
Plants affected Salix
Main causes Fungus
Timing Spring to Summer

What is willow anthracnose, scab and canker?

Three fungal pathogens cause dark leaf blotches and shoot dieback of willow in the UK:

  1. Drepanopeziza sphaerioides (willow anthracnose) – affecting leaves and stems
  2. Venturia saliciperda (willow scab) – affecting leaves and stems
  3. Glomerella miyabeana (willow black canker) – affecting stems only



  • Blackish spots appear on the leaves, whose development may be distorted, and irregular black raised lesions occur on the young stems. Weeping willow is very susceptible to this disease 
  • Leaves and stems are shed, leading to a sparse crown


  • Irregular black spots appear on new season's growth, causing black, shrivelled shoots

Black canker:

  • Symptoms are as for scab, but appear later in the season and spread to older growth where sunken cankers appear on the stem


Non-chemical control:

  • Raking up and destroying fallen leaves from anthracnose-infected trees will only be of limited value, because it is lesions remaining on the tree which are the most important source of infection
  • On young trees prune out infected shoots promptly. Damage done by bark infection is proportionately more severe when the stems are small

Resistance: Salix × sepulcralis var. sepulcralis and S. 'Erythroflexuosa' are resistant to anthracnose and other willow species are hardly affected. Salix alba var. caerulea, S. pentandra and S. purpurea are resistant to one or both of scab and black canker.

Chemical control:

There are no chemical controls specifically available for these diseases and it would not be practicable to spray mature trees in any case.

However, the fungicides tebuconazole (Bayer Fungus Fighter Concentrate), tebuconazole with trifloxystrobin (Bayer Fungus Fighter Plus), and triticonazole (Scotts Fungus Clear Ultra and Scotts Fungus Clear Ultra Gun) are labelled for the control of a number of other diseases on ornamental plants, and may give some control of anthracnose, black canker and scab on young, establishing trees.

The following products contain a combination of both insecticide and fungicide, enabling the control of both insect pests and disease: myclobutanil containing cypermethrin (Bayer MultiRose 2, Doff Rose Shield, Vitax Rosegarde, Westland Rose Rescue); tebuconazole containing deltamethrin (Bayer Multirose Concentrate 2), and triticonazole containing acetamiprid (Scotts Roseclear Ultra and Scotts Roseclear Ultra Gun). When a proprietary product contains an insecticide as well as a fungicide it would be preferable to use an alternative product if pests are not a problem on the plants treated.


Fungicides for gardeners (Adobe Acrobat pdf document outlining fungicides available to gardeners)


Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: storing and disposing safely


The fungi which cause these diseases produce spores on the affected tissues. They are spread in water and the diseases are therefore worst in wet weather. Severe attacks of anthracnose on the very susceptible and commonly planted weeping willow (Salix × sepulcralis var. chrysostoma) can leave the tree almost leafless, but the disease is of little consequence on other willows.

Anthracnose differs from scab and black canker by the fact that anthracnose-infected tissues are shed, whereas the shoots killed by the last two diseases remain on the tree. However, not all anthracnose-infected shoots are shed, and those that remain on the tree form the most important source of infection in following years, since the spores they produce are very readily dispersed around the tree in rainwater.

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