symptom
Mainly damages leaves. The lesions are nearly round or shapeless, with a diameter of 1 cm or more, with brown edges, taupe to off-white middle, and obvious concentric ring patterns. There are very dense small black spots on the lesions, that is, the pycnidium of the pathogenic bacteria, and the severe leaves turn yellowish brown or dry. It occurs from December to April of the following year in the south, and from June to July in the north, and often lasts until the end of September. False ring spot of strawberry is similar to that of ring spot, and the lesions sometimes show a yellow halo, and the diseased part is small in brown or dark brown.
Pathogen
Strawberry brown ring spot mainly damages leaves. The lesions are nearly round or shapeless, with a diameter of 1 cm or more, with brown edges, taupe to off-white middle, and obvious concentric ring patterns. There are very dense small black spots on the lesions, that is, the pycnidium of the pathogenic bacteria, and the severe leaves turn yellowish brown or dry. It occurs from December to April of the following year in the south, and from June to July in the north, and often lasts until the end of September. False ring spot of strawberry is similar to that of ring spot, and the lesions sometimes show a yellow halo, and the diseased part is small in brown or dark brown.
Transmission routes and disease conditions
It overwinters in the diseased leaf tissue with mycelium and pycnidia or in the soil left by the diseased debris, and becomes the source of infection at the beginning of the next year. The overwintering pathogen produces conidia in April to May of the following year, which is spread by rainwater splashing for initial infection, and then the diseased part continues to produce conidia for multiple re-infections, so that the disease gradually spreads and expands. The onset begins in late April with an average temperature of 17°C, gradually expands after mid-May, and enters the peak period from late May to June. After late July, the disease is suppressed when encountering high temperature and drought, but if it is warm and humid, especially in season Sunny and rainy times occur repeatedly, and the condition expands again. Disease resistance varies among varieties.
Prevention method
(1) Select disease-resistant varieties according to local conditions.
(2) Remove the diseased leaves on the seedlings before planting, soak the seedlings with 500 times liquid of 50% carbendazim wettable powder for 15-20 minutes, and plant after the liquid is dried.
(3) In the early stage of the disease, the field began to spray 3000 times of 30% diphenoxymethyl propane EC or 600 times of 62.25% Nitrile wettable powder or 500 times of 40% polysulfur suspension concentrate, 50% polysulfide Fu suspension concentrate 500 times liquid, once every 10 days or so, continuous control 2 to 3 times.
