Pathogenesis and preventive methods of tomato early blight

(1) Incidence of disease

Tomatoes with early blight have angular tomato ringworm disease. Hazardous time is long and occurs early. It is a common hazard. When the onset is severe, the leaves are withered and the yield is reduced.

Early blight attacks leaves, stems, and fruits. The leaves were damaged, and the water was immersed in small brown spots. After expansion, they were round or oval in shape, with a diameter of 1-3 cm. The lesions were dark brown in the edges, brown in the center, and concentric rings. The lesions in the later stages were sometimes broken. Black mould grows on the spot when wet. The lesions on the stalks occurred mostly at the branches, and were gray-brown, oval-shaped, slightly sunken, with rims or inconspicuous, and severe fragments. The onset of fruit is mostly brownish or dark brown on the shoulders, slightly sunken, with concentric ringworm lesions and brown moldy tops.

The pathogenic bacteria was Tomato early blight bacteria. The pathogenic bacteria mainly used hyphae and conidiophores and conidia with the diseased bodies to overwinter in the field. The pathogens survived for more than one year, and the pathogens on the seeds survived the disease for two years. The bacteria invade from the stomata or wound and can also penetrate directly from the epidermis. Under suitable conditions, 2-3 lesions are formed. In the 3-4 days, a large number of gowns are generated in the diseased part and reinfested by wind, water, and insects.

The bacteria can infect at 1-15 degrees, relative humidity more than 80%, 20-23 degrees, the condition develops rapidly, and develops faster when it is above 25 degrees.

(2) Control methods

The disease-free seeds were selected and soaked in 50-degree hot water for 30 minutes. The non-sorrel crops were rotated for more than 3 years to control the humidity, and the phosphorus and potassium fertilizers were applied to increase the resistance of the plants and enhance the resistance to diseases. .

The diseased leaves and fruit were found to be removed in time, 80% mancozeb WP was used 500 times, polothane WP 500 times, or 50% thiophanate-methyl WP 800-1000 times. Or 40% bacteriochlorin 40% sterilization Dan (1:1) 1000 times alternately spraying cloth.

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