Control of black rot of green cauliflower after waterlogged cotyledons

Green cauliflower is a new variety introduced from abroad, and its unique flavor, nutrition and color are favored by people. With the expansion of planting area, the occurrence of black rot is generally serious, and it has become an important disease in planting green cauliflower.

Black rot of green cauliflower

First, symptoms:

The disease can occur from seedling to adult stage. When the seedlings are sick, the cotyledons are waterlogged, and then die quickly or vine to the true leaves. When the disease occurs in the adult stage, it mainly harms the leaves, first from the edge of the leaves, forming V-shaped withered spots that expand inward. The disease spot is yellowish brown and the edge is yellowish. The roots were damaged, the vascular bundles blackened, the internal dry rot, and even the whole green cauliflower wilted and died.

Second, the regularity of the disease:

Black rot is caused by bacteria of the genus Xanthomonas. The pathogen overwinters in seeds, plants and diseased bodies in the soil, and insects and agricultural operations can also spread. Infected seeds are the main source and can be transmitted over a long distance. After sowing the seeds with bacteria, after the seedlings were unearthed, the bacteria invaded from the water pores at the edge of the cotyledons of the seedlings and gradually expanded to the vascular bundles, causing the disease of the whole plant. The pathogens in the soil could be transmitted to the leaves through Rain Water and irrigation water, invading from stomata and water pores, causing the disease, first infecting a small number of parenchyma cells, and then rapidly invading the vascular bundles, causing systematic infection.

High temperature and humidity is conducive to the disease, the temperature is 5 ℃ ~ 39 ℃, the appropriate temperature is 25 ℃ ~ 30 ℃, the relative humidity is more than 95%, especially leaf condensation, leaf edge spitting water, conducive to the invasion of bacteria. Early sowing, low-lying terrain, heavy soil, too much watering, continuous cropping with cruciferous vegetables, application of immature fertilizer, pests are serious disease in the seriously damaged land.

3. Comprehensive prevention and control measures:

Seed selection and seed treatment: select disease-free plants to keep seeds, soak in 50 ℃ warm water for 20 minutes before sowing, or soak in agricultural streptomycin 1000 times solution for 2 hours. During live broadcast, 50% Fumishuang can be used to mix seeds according to the seed weight of 0.4%.

Strengthen field management: rotation of seriously diseased plots. Timely sowing, adequate manure application, timely drainage after rain, avoiding excessive drought and waterlogging, and timely removal of diseased leaves, complete removal of diseased bodies during harvest, and reduction of primary infection sources in the field.

Chemical control: in the early stage of the disease of green cauliflower, timely use of agricultural streptomycin 200 mg / kg; or neoptomycin 100 mg / kg; or 60% Chlorothalonil wettable powder 600 times solution; or 1purpura 200 times 240 times Bordeaux solution, or 77% can kill 500 times wettable powder solution. The above agents are used alternately and have good control effect.