Integrated control of white spot disease of mustard

Mustard is an annual or biennial herb of Cruciferae and Brassica. It is a famous specialty vegetable in China. It is native to China and is commonly cultivated all over the country, mostly distributed in the provinces south of the Yangtze River. Mustard like cold, cool and moist, avoid heat, drought, slightly resistant to frost. The average temperature suitable for seed germination was 25 ℃. The average temperature for leaf growth of mustard is 15 ℃, and the temperature for edible organ growth is 8-15 ℃. But stem mustard and heart mustard require lower temperature for the formation of edible organs, and leaf mustard generally requires less temperature.

Species distribution of mustard

Except for cold and arid areas, there is no distribution boundary of mustard in China. It extends to coastal provinces in the east, Xinjiang Uygur Autonomous region in the west, Sanya City in Hainan Province in the south and Mohe City in Heilongjiang Province in the north. Mustard is cultivated from the middle and lower reaches of the Yangtze River to the Qinghai-Tibet Plateau.

Growth habits of mustard

Budding, bolting, flowering and fruiting need to go through the conditions of low temperature vernalization and long sunshine. Autumn sowing is dominant in the north and south of China, the Yangtze River Basin, southwest and South China are harvested in winter or the next spring, and the north is harvested before frost. Leaf mustard eaten by young plants can be sown in spring or summer in the south. During the growing period, it is easy to bolt when exposed to long sunshine, which affects the growth of edible organs.

Integrated control of white spot disease of mustard

The disease mainly harms cruciferous vegetables such as mustard, Chinese cabbage, cabbage, cabbage and radish. The occurrence is common in China, and serious in North and Northeast China.

Symptoms of white spot disease of mustard:

The main damage to leaves. At the beginning of the disease, there are tiny grayish brown tiny round spots on the leaf surface, and then gradually expand into round, irregular or round disease spots, the center becomes gray-white, there are 1-2 inconspicuous wheel lines, and there are pale or yellowish green halos around the edge, about 6-18 mm in diameter. In the later stage, the disease spots merged with each other to form irregular large disease spots. When damp, the back of the disease spot produces a light gray mildew. In the later stage, the lesion became white and translucent and ruptured and perforated. Generally, the outer leaf occurs first and spreads upward.

The conditions for the occurrence of white spot disease of mustard:

The disease is a fungal disease. The pathogen overwinters on the soil surface with the residue of the diseased plant, and it can also overwinter on the seed or seed plant. The following spring spread with the wind and rain. The temperature range of white spot disease was 5-28 ℃, and the optimum temperature was 11-23 ℃. The air relative humidity suitable for the disease is more than 60%. It is easy to occur in the weather of low temperature, large temperature difference between day and night, dew in the field, foggy and rainy weather. In addition, continuous cropping, low-lying terrain and too much watering. Factors such as early sowing can also cause the epidemic of the disease. There are also some differences in disease resistance among different varieties.

Integrated control methods of mustard:

Resistant varieties were selected for ① varieties.

② rotation and non-cruciferous crop rotation for 2-3 years.

Disease-free seed plants were selected for ③ seed treatment to prevent seed from carrying bacteria. The infected seeds can be soaked in 50 ℃ warm soup, or the seeds can be treated at 70 ℃ for 2-3 days to kill the germs on the seeds.

④ field management is suitable for late sowing to avoid the environmental conditions of the disease, increase the application of organic fertilizer, cooperate with phosphorus and potassium fertilizer, supplement trace element fertilizer, remove the diseased plants in the field in time and reduce the source of the disease.

⑤ medicament can be used to prevent and cure the disease at the beginning of the disease, 15% azinamide 300x liquid, 50% Mizujing 500x liquid, 40% polysulfide 600x liquid, 40% mixed thiophanate 600x solution, 50% carbendazim 800x solution, Dasheng Mashi 45 400,600x liquid. One of the above drugs, or alternately, once every 15 days, spray 2-3 times.