Black rot mostly damages cruciferous crops, such as cabbage, cabbage, cauliflower, radish, mustard and turnip. Cabbage, cauliflower, and radish are more severely damaged, and the losses are also greater.

symptom

Black rot is a vascular disease caused by bacteria. Its symptom is characterized by causing necrosis of vascular bundles and turning black. The seedlings become ill, and the cotyledons appear water-soaked, gradually die or spread to the true leaves, and continue to develop. Small black spots or thin black stripes appear in the veins of the true leaves. The disease of adult plants usually starts from the lower leaves, mostly from the leaf margins or insect wounds, forming "V"-shaped yellow-brown lesions, forming leaf veins necrosis and blackening, and the bacteria can spread along the leaf vein petiole to the stems and roots, causing the stems , The vascular bundles at the roots turn black, form reticulate veins, and plant leaves die.

pathogen

Caused by Xanthomonas infestation. The suitable growth and development of the bacteria is 25-35 degrees Celsius, the lowest is 5 degrees Celsius, the highest is 38-39 degrees Celsius, and the lethal temperature is 51 degrees Celsius for 10 minutes. Resistant to drying.

Causes

Diseases mostly occur in spring and autumn, with mild disease in spring and severe disease in autumn.

In autumn, the temperature is relatively high and the incidence of rain is severe.

Sowing too early and serious pests are prone to disease.

Improper cultivation methods, uneven borders and stagnant water are prone to disease.

Improper fertilization and watering can also easily catch diseases.

way for spreading

The pathogens are introduced from the stomata of the leaf edge of the cotyledons, and the adult plants are mostly introduced into the vascular bundles from the water holes and wounds of the leaf edge and expand up and down, resulting in systemic infection of the entire plant.

Spread in field rain, pesticides, insects, fertilizers, and agricultural activities.

Inadvertent watering and hoeing have high humidity and spread.

The diseased plants can spread if the fallen leaves are not removed in time.

Cruciferous plants such as vegetables, radishes, and cabbage that have been planted for many years are also easy to spread.

Prevention

(1) Agricultural control

Choose good varieties that are resistant to black rot.

Choose a plot with high terrain and good drainage.

Strive for 2-3 years of crop rotation with non-cruciferous crops.

Treat diseased plants and leaves in time to prevent infection.

If the diseased plants are found, they should be pulled out and burned and buried deeply.

Cultivation in an appropriate period, strengthen management after planting, fertilize and water properly, and improve plant disease resistance.

(2) Drug prevention and treatment

1. 7-1 Seed disinfection: Soak the seeds in warm water of 50 degrees Celsius for 20-30 minutes, or wash the seeds with 50% ammonium ammonium for 15 minutes, or dress the seeds with 0.4% thiram, wash and dry before sowing.

2. At the initial stage of the disease, 1:1; 200 Bordeaux liquid spray.

3. Streptomycin sulfate or chloramphenicol 50-100ppm spray for 7-10 days/time, spray continuously for 3-4 times (reproduced)