Control of downy mildew of mustard disease

Mustard (Brassica juncea) is an annual or biennial herb of Brassica in Cruciferae. It is a famous vegetable native to China. It is a commonly used vegetable cultivated all over the country, mostly distributed in the provinces south of the Yangtze River. The main and lateral roots of mustard are distributed in a soil layer of about 30 cm. The stem is a short shrinking stem, and the leaves are in the shape of oval, oval, obovoid, lanceolate, etc., with green, dark green, light green, yellow-green, green lines or purplish red. It is rarely cultivated in Europe and the United States and originated in Asia.

Morphological characteristics of mustard

Mustard (original variety) annual herbs, 30-150 cm tall, often glabrous, sometimes young stems and leaves prickly, powdery, spicy; stems erect, branched. Basal leaves broadly ovate to Obovate, 15-35 cm long, tip rounded-obtuse, base cuneate, pinnatifid, with 2-3 pairs of lobes, or indehiscent, margin notched or dentate, petiole 3-9 cm long, with lobules; lower stem leaves smaller, margin notched or dentate, sometimes obtusely serrate, not clasping. Upper leaves of stem narrowly lanceolate, 2.5-5 cm long and 4-9 mm wide, margin inconspicuously sparsely dentate or entire.

Racemes terminal, elongated after anthesis; flowers yellow, 7-10 mm in diam.; pedicels 4-9 mm long; sepals yellowish, oblong-elliptic, 4-5 mm long, erect; petals Obovate, 8-10 mm long, 4-5 mm long. Siliques linear, 3-5.5 cm long and 2-3.5 mm wide, petals with 1 prominent midrib; beak 6-12 mm long; fruiting pedicel 5-15 mm long. Seeds globose, ca. 1 mm in diam., purple-brown. The flowering period is from March to May and the fruiting period is from May to June.

Control of downy mildew of mustard disease

What is downy mildew?

Downy mildew is to be called "baking disease", "horse running dry" and so on. It mainly harms cruciferous vegetables such as mustard, Chinese cabbage, cabbage, cabbage and radish. It is common in all parts of the country, and the harm is very serious. Mustard disease downy mildew symptoms:

It mainly harms leaves, followed by stems, pedicels and seed pods. The disease starts from the outer leaf, the leaf front appears light green to light yellow spots, after expansion, it is yellowish brown, and becomes a polygonal class due to the limitation of leaf veins. White mildew occurs on the back of the lesion when it is wet. In severe cases, a large number of outer leaves withered and died. Seed plant disease, stems, pedicels, flower organs, seed pods are growing white mold, deformities. The seed pods are yellowish, with black-brown long stripes, small and curved, and less fruiting. Incidence conditions of downy mildew of mustard disease:

The disease is a fungal disease. The pathogen overwintered in the soil with the residue of the diseased plant, and it could also overwinter on the mother plant. The following year, the infection was spread by wind and rain. The disease occurred rapidly at 16-20 ℃, and the epidemic was serious when it was rainy, dewy and lack of sunshine. In addition, when continuous cropping, continuous cropping, low-lying land, poor ventilation, excessive density, malnutrition and weak growth, the disease is serious. When the virus disease in the field is serious, downy mildew is also serious. There were also differences in disease resistance among different varieties. Prevention and control of downy mildew of mustard disease:

① varieties were selected with disease resistance.

Before disinfecting and sowing ② seeds, use 50% thiram of 0.3% of seed weight, or 25% trichlorothalonil, or 75% chlorothalonil, to eliminate germs on the seed surface.

③ reasonable rotation, suitable sowing and cruciferous crop rotation every other year, neighboring cropping also avoid cruciferous crops to reduce the source of infection. The sowing date of autumn and winter cultivation should be postponed to avoid high temperature and rainy season.

In ④ field management, diseased seedlings and weak seedlings were removed in time at seedling stage, and after harvest, the fields were cleaned and the soil was deeply ploughed to reduce the source of disease. Apply sufficient organic fertilizer, increase phosphorus and potassium fertilizer, timely watering and topdressing during the growing period to ensure the robust growth of plants and enhance disease resistance.

⑤ agents can be used in the initial stage of disease prevention and treatment with 40% ethanophosphate aluminum 300x solution, 25% Ruidu 800x solution, 64% poisonous alum M8 500x solution, 72.2% Pulike 600-1000 fold solution, Dasheng Mmur45 400600-600x solution. One of the above drugs may be used alternately, once every 7-10 days, and sprayed 3-4 times.