What are the diseases and pests of rapeseed seedlings? How to prevent and control rapeseed seedling pests

Rapeseed is a common vegetable in life. It is deeply loved by people because of its rich nutrition and its effects of widening the intestines, detoxifying and reducing swelling. However, many people encounter problems with diseases and pests when growing rapeseed. So what are the diseases and pests of rapeseed seedlings? How to prevent and control rapeseed seedling pests? The following editor will explain them one by one, hoping to help everyone.

What diseases and pests are there in the rapeseed seedling stage?

1. Rapeseed Sclerotinia

The disease mainly harms the stems, but also leaves, flowers and pods. The lesions on the stems are light brown at first, slightly sunken, and then turn grayish white. When the humidity is high, the diseased part becomes soft and rotten, and white floccules (mycelium of the pathogen) grow on the surface. The cortex of the pathogen rots, and the main stem becomes hollow, with large black sclerotia inside, which look like rat droppings. Sometimes sclerotia also grow on the stems. The disease begins to occur during the flowering period of rapeseed and continues to harm until the maturity period.

2. Downy mildew of rapeseed

This disease can occur throughout the entire growth period of rapeseed, causing leaf withering and inflorescence deformity. The disease can damage leaves, stems, flowers and fruit. The disease symptoms are the initial appearance of light yellow, inconspicuous lesions on the front of the leaves, which are polygonal, and white frosty mold grows on the diseased parts on the back of the leaves. This causes a decrease in the yield and quality of rapeseed.

3. Rapeseed mosaic disease

The characteristic symptom of rapeseed mosaic disease is that after infection, the young leaves will have visible veins. All or part of the veins will be light yellow (slightly transparent when viewed in light), followed by mosaic symptoms (i.e. alternating yellow-green and dark green). A few leaves will be deformed, the plant will be dwarfed, and the number of unfilled grains will increase. In severe cases, the whole plant will shrink and become deformed, and water-soaked, brown to dark brown dead streaks will often appear on the stems. Severely infected plants will often die early due to bending caused by the disease.

How to prevent and control rapeseed seedling pests

1. Spraying foliar fertilizer during drought can alleviate the impact of drought. Rapeseed plants grow slowly due to drought. Spraying foliar fertilizer can effectively supplement the insufficient fertilizer absorption by the roots, promote rapeseed growth, and increase the cold resistance of the plants.

2. After the drought ends, apply five to ten kilograms of urea (per mu) in time to allow the rapeseed to quickly resume growth.

3. For fields planted later, the number of seedlings should be controlled and the density of rapeseed in the field should be increased. More than 20,000 seedlings should be left per mu to give full play to the group advantage of rapeseed, which can effectively reduce yield losses.

4. Prevent pests in time. In high temperature and drought, aphids grow faster and have a greater impact on the growth of rapeseed plants. It is recommended to use low-toxic and high-efficiency pesticides such as imidacloprid, add water according to the package instructions, and spray once or twice before 10 am or after 5 pm, avoiding the high temperature period at noon, which can effectively control the damage of aphids.

How high can rapeseed be cut to the tip?

Rapeseed is the main source of edible vegetable oil in China and is grown in many places in China. Rapeseed topping is mainly to make the plant grow more new branches, which can increase yield and wind resistance. Rapeseed should be watered and fertilized frequently after transplanting to ensure the plant grows healthily. Generally, branches with flower bags will appear in more than two months, and at this time, you can top it according to the number of flowers. However, the more branches, the better. Too many branches are not good, and it cannot guarantee that the rapeseed harvested at that time will be full. When the rapeseed is not full enough, it will directly affect the oil yield.