- Little can be done by cultural means to prevent infections when conditions are suitable. Plants may sometimes 'grow through' the problem, with new leaves being unaffected when growing conditions change so that they are less conducive for the diseases
- If the attack is very unsightly, consider trimming to remove affected leaves and encourage new growth. However, avoid heavy pruning as this will stress the plants and may aggravate the problem
- Feeding may be helpful, although laurel is usually robust enough not to require it
The fungicides tebuconazole (Provanto Fungus Fighter Concentrate), tebuconazole with trifloxystrobin (Provanto Fungus Fighter Plus, Toprose Fungus Control & Protect), and triticonazole (Scotts Fungus Clear Ultra and Scotts Fungus Clear Ultra Gun) are approved for the control of powdery mildews on ornamental plants. Tebuconazole with trifloxystrobin also carries a recommendation for control of 'leaf spots' of ornamentals, and may have some activity against the fungal leaf spot diseases of laurels. It is unlikely to have activity against bacterial leaf spot.
The following products contain a combination of both insecticide and fungicide, enabling the control of both insect pests and disease: myclobutanil containing cypermethrin (Westland Resolva Rose 3 in 1, Doff Rose Shield Bug & Fungus Killer, Scotts Roseclear Ultra Gun 2, Vitax Rosegarde) 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.
SB Plant Invigorator, Resolva Natural Power Bug and Mildew Control, RHS Bug and Mildew Control, Ecofective Bug & Mildew Control and the Ecofective ‘Defender’ range contain a blend of surfactants and nutrients and can be used on any edible or ornamental plants, with no harvest interval. They have a physical mode of action and may be used against powdery mildews, as well as a range of pests such as whiteflies, aphids, spider mites, mealybugs, scale insects and psyllids.
Inclusion of a product does not indicate a recommendation or endorsement by RHS Gardening Advice. 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