The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.
- 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.
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 (Provanto Fungus Fighter Concentrate), tebuconazole with trifloxystrobin (Provanto Fungus Fighter Plus, Toprose Fungus Control & Protect), and triticonazole (Fungus Clear Ultra) are labelled for the control 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 (Resolva Rose 3 in 1, Rose Shield Bug & Fungus Killer, Roseclear Ultra Gun 2, Rosegarde) and triticonazole containing acetamiprid (Roseclear Ultra, 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.
Inclusion of a product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener.
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