Arbutus are evergreen trees or shrubs, some of which also produce attractive red fruits. They can sometimes be affected by fungal leaf spot diseases, which may spoil their appearance and, in severe cases, lead to leaf loss and twig dieback.
What are Arbutus leaf spots?
Leaf spots on arbutus are usually caused by one of two fungi. Elsinoë mattiroloanum is the more common and damaging, may be found on twigs as well as leaves, and can lead to leaf loss and twig dieback. Attacks by Ruptoseptoria unedonis are usually confined to the leaves.
Symptoms
You may see the following symptoms:
Elsinoë mattiroloanum
- Small purple leaf spots, often enlarging to form prominent purple ring spots (an outer purple ring with a green or yellow centre)
- Purple, slightly raised, lesions on twigs
- Leaves may turn yellow and fall prematurely
- Twigs may die back
Ruptoseptoria unedonis
- Small, brown to purple leaf spots, circular to more irregular in shape
- Larger spots develop a whitish centre
Control
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.
Non-chemical control
- Remove and destroy affected leaves, or twigs with dieback, together with fallen leaves at the base of the plant
- Encourage the production of
vigorous, healthy growth by feeding, mulching to conserve moisture and watering of plants during periods of extended drough
Chemical control
The fungicide tebuconazole with trifloxystrobin (Provanto Fungus Fighter Plus, Toprose Fungus Control & Protect) has a recommendation for the control of leaf spots on ornamental plants. Additionally, the fungicides tebuconazole (Provanto Fungus Fighter Concentrate) and triticonazole (Fungus Clear Ultra) are labelled for the control of other diseases on ornamental plants, and could therefore be used legally on arbutus (at the owner’s risk) to try and control the leaf spotting.
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.
There is no specific information available as to the efficacy of these products against arbutus leaf spots, however. It would be prudent to apply a small amount of the chosen fungicide first, at a solution suggested on the packet for other problems, to ensure that the product will not cause plant damage.
GOOD LUCK
——————————————————————————-
CLEAN AGRICULTURE VIETNAM VTNN CO., LTD
Address: Nguyen Trai Street, Residential Area 4, Hiep Tam 2 Quarter, Dinh Quan Town, Dinh Quan District, Dong Nai Province, Vietnam
Chuyên Thuốc bvtv _ hạt giống_ dụng cụ nông nghiệp
📲📲Hỗ Tư vấn kỹ thuật tại vườn📲📲
✅Hotline: 0919.817.033
✅Link web: https://vietnamnongnghiepsach.com.vn/
✅Link youtube 1: https://www.youtube.com/c/TrịBệnhChoCâyTrồng
✅Link youtube 2: https://www.youtube.com/c/KiếnThứcNôngNghiệp
✅Link Zalo: https://zalo.me/0919.817.033
✅Link Lazada: https://www.lazada.vn/shop/viet-nam-agricultural-supermarket
——————————————————————————————————-
