Control Techniques for Snake Eye Disease in Strawberry Cultivation

As autumn arrives, temperatures drop, rainfall increases, and light is insufficient, snake eye disease begins to occur frequently in some strawberry-producing areas. In some fields, the incidence rate reaches over 50%, seriously affecting strawberry growth. The main occurrence and control techniques are introduced as follows:

1. Disease symptoms: It mainly damages leaves. It usually starts on the lower old leaves and gradually develops upward. In the early stage of the disease, many nearly round, purplish-red small spots of varying sizes appear on the leaves, resembling snake eyes. Later, the central spots turn grayish-white to grayish-brown and form large spots, sometimes with purplish-red concentric rings. When humidity is high, a white powdery mold layer forms on the surface of the lesions, namely the pathogen's conidiophores and conidia. In the later stage, many small black dots, namely the pathogen's ascocarps, can be produced on the lesions. When severe, the lesions are densely distributed on the leaves, and within a short time the affected leaves necrose and dry up. 2. Disease characteristics: This disease is especially likely to occur in fields where strawberries have been planted for many years. The pathogen develops at 7-25°C, with 18-22°C being most suitable. There are slight differences in disease severity among varieties. It generally occurs at the seedling stage and mainly damages leaves and petioles. In the early stage, it closely resembles snake eyes. When severe, several lesions merge into one large lesion until the leaves completely die. 3. Control methods. 1. First, comprehensive control methods must be adopted, because the pathogen overwinters as mycelium with diseased residues. Therefore, strawberries should not be continuously planted in the same field as much as possible. Generally, the planting site should be rotated every 2-3 years, and prevention should be carried out before disease occurs. 2. Lower the groundwater level; the field must have good drainage and ventilation, which can effectively reduce disease occurrence. Early prevention and early control can achieve twice the result with half the effort and can greatly reduce the cost of pesticide control. 3. Strictly remove diseased seedlings when transplanting. Before transplanting, soak the seedlings in a solution of the appropriate pesticide, and plant them after they dry. In the early stage of disease, promptly remove diseased leaves and take them out of the field for proper disposal to prevent diseased leaves from repeatedly infecting healthy plants. 4. Use pesticides for control in the early stage of disease. Currently effective pesticides include the broad-spectrum therapeutic fungicide 25% Kairun emulsifiable concentrate, which can treat and eradicate the disease, generally used twice; 60% Baitai water-dispersible granules at 1500 times can also be mixed with carbendazim or thiophanate-methyl for control. The key to disease control lies in prevention. 60% Baitai water-dispersible granules can be used for prevention starting at the seedling stage, once every 7-10 days, and can effectively control the occurrence of multiple diseases. Mancozeb, thiophanate-methyl, or carbendazim can also be sprayed at the seedling stage for control. If one packet (2 grams) of Shuofeng-481 natural brassin is added to the pesticide solution in each backpack manual sprayer, it can quickly promote plant growth and recovery from the effects of the disease on the plants. In the early stage of disease, spray 30% Ludeobao suspension at 400 times, 14% copper ammonia complex aqueous solution at 300 times, 77% Keshade wettable powder at 500 times, 75% chlorothalonil powder at 500 times, or 70% mancozeb wettable powder at 350 times. Spray once every 10 days, for a total of 2-3 times. Stop using pesticides 3 days before harvest.