Early blight mainly affects leaves and can also invade tubers. At the initial onset, some sporadic brown spots appeared on the leaves, and the lesions gradually enlarged, showing an irregular shape with concentric circles. There is a narrow fading ring around the lesion. When the disease is severe, the leaves of the plant gradually dry out from the bottom to the top, and only a few leaves on the top remain green.
The route of transmission and the law of onset: The disease is caused by the infection of the fungus Aspergillus spp., and the pathogens overwinter with the diseased tissue in the soil, and can also overwinter on the lesions of the potato block. Conidia can survive for a long time, spread by wind and rain, and repeatedly infect during the growth of the host. High temperature is beneficial to the infection of early blight; the old leaves of degraded and debilitated plants are prone to disease; the plots with thin and lack of fertilizer are seriously affected.
Control method 1. Seed selection: Select early-maturing and disease-tolerant varieties, soak seeds with new high-fat film, soak them and dry them after drying. It can keep warm, moisturize and swell, improve the germination rate of seeds and make the seedlings strong. Repel underground pests and isolate viral infections. 2. Site selection: Choose to plant in a place with fertile soil and high ground. 3. Fertilization: Add organic fertilizer, increase phosphorus and potassium fertilizer, and improve the disease resistance of plants. 4. Chemical control: In the early stage of the disease, spray with a targeted biocide with 500 times liquid new high-fat film, spray once every 7 to 10 days, and spray continuously for 2 to 3 times.
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