Cabbage Black Spot Control Technology

In recent years, cabbage black spot disease has been on the rise in Guangdong vegetable areas. Autumn and winter seasons occur in Chinese cabbage, cabbage, Shanghai green, black leaf white and other varieties, to the turn of winter and spring, overcast and rainy days, warm and humid when the outbreaks often occur, seriously affecting the yield and quality.

Cabbage black spot mainly damages leaves, petioles and cotyledons. The early stage of disease in the leaves is an almost round, chlorotic small spot, which gradually enlarges to a brown spot with a diameter of 5-10 mm. There are obvious concentric ring patterns, with light green to dark brown edges, and some spots with yellow halos. Humidity When it is large, it produces dark brown moldy layer, and the diseased part is perforated under high temperature and high humidity conditions. In severe cases, lesions converge into large plaques, causing half-leaf or whole leaves to die, and the entire plant leaves dry from the outside to the inside. The lesions on the petioles and stems are spindle-shaped and dark brown in shape.

The disease is caused by the fungus Streptomyces sp. The mycelia are hidden in the seeds and field diseases. When conditions are suitable, they produce spores and spread. They invade from the stomata or directly through the epidermis. The lesions appear within 3-5 days of incubation, and the conidia spread with wind and rain and agricultural tools. Infection. The bacteria can normally grow and develop at 0-35°C. The optimum temperature is 17-25°C, so it can occur in Guangdong in the anniversary. Rainy weather persists, the weather is warm, the planting is too dense, the watering is too much, the humidity in the field is too large, and the variety disease resistance is poor.

The effective techniques for controlling black spot of cabbage are as follows: Select disease-resistant varieties suitable for the local area as much as possible, rotate with non-cruciferous crops for 2-3 years, deepen the soil for deep preparation, apply organic base fertilizer, and reasonably apply fertilizer in combination with organic trace elements and compound nutrition. Liquid to improve the disease resistance of vegetables, as well as appropriate close planting and appropriate watering. In addition, the following specific measures need to be taken: (1) soaking in warm water at 50°C for 25 minutes before sowing, cooling and then reseeding after cooling; or using 0.4% seed of Baoning (60% wettable powder) or Fome Double (50% wettable powder) can also be used seed dressing 0.3% acetaminophen (50% wettable powder) seed dressing. (2) In the mid-seedling stage (especially when lesions are found), spray the medicine in time. For the selected agents: 500-600 times for Baoning; 600-800 times for Baikoning or chlorothalonil (40% suspension); Calcium Chloride (64% wettable powder) 800 times; Propogon (70% wettable powder) 700-800 times; Pentocaine 1500 times; Green Cape (70% WP) 500 times. Once every 7 days, spray 3-4 times.

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