What are the methods for controlling pests and diseases in rapeseed?

Rapeseed, also known as oil cabbage and bitter cabbage, is one of China's important grain and oil crops due to the high oil content of its seeds, and is mainly distributed in Anhui, Henan, Sichuan and other places. However, during the rapeseed growing process, its resistance to pests and diseases is relatively weak, so strengthening pest and disease control in rapeseed is the key to increasing yield. So what pests and diseases affect rapeseed? How should they be controlled? Let's take a look.

1. Sclerotinia rot

Sclerotinia rot can infect rapeseed from emergence to maturity, with the highest incidence during the flowering period, and it causes great harm over a wide range. When it occurs, it damages the stems, flowers and leaves of rapeseed, and light brown lesions appear on the affected parts, turning grayish white as the disease progresses. If field humidity is high, the lesions may also develop rot, and a white mold layer will grow on the rotting areas.

Control method: During the flowering period of rapeseed, carry out intertillage and earthing up 2-3 times, which can promote root growth and also prevent sclerotinia rot. After rain, drain water promptly to reduce field humidity, reasonably control the fertilizer ratio, and spraying carbendazim during the flowering period effectively controls sclerotinia rot.

2. Downy mildew

Downy mildew mainly occurs when long periods of rainy weather and other conditions cause high field humidity, and it mainly damages the leaf parts of rapeseed. When leaves are affected, grayish white or light yellow irregular lesions appear on the upper surface of the leaves. Once lesions appear, multiple lesions will develop and may connect with one another, and in the later stages of the disease, the leaves will die off over large areas.

Control method: The control method for downy mildew is similar to that for sclerotinia rot. Strengthen field management, apply more phosphorus and potassium fertilizer to enhance disease resistance, drain water promptly after rain to prevent the spread of pathogens, and in the early stages of the disease, spray anchormancozeb for control.

3. Aphids

Aphids are one of the main pests harming rapeseed. They are found throughout China's main rapeseed production areas and are more rampant in dry winter environments or in soil lacking moisture. Aphids feed on the tender tissues of rapeseed. In addition to causing damage to leaves, they also leave behind their own secretions, greatly affecting plant growth. Moreover, aphids are also transmitters of various diseases, making them extremely harmful.

Control method: Aphid control should combine physical and chemical methods. First, carry out intertillage properly, and before flowering, carry out intertillage and earthing up, with reasonable close planting to ensure field ventilation. When the number of aphids is large, spray pirimicarb water-dispersible powder for control, once every week for 2-3 consecutive times, with good results.

4. Green caterpillars

Green caterpillars mainly cause damage as larvae, and the degree of feeding varies with growth stage. Third-instar green caterpillars can completely devour a whole plant in a short time, causing great harm. If not controlled in time, the loss to rapeseed is enormous. Somewhat similar to aphids, their droppings also affect rapeseed growth and harm the health of plant growth.

Control method: For green caterpillar control, manual capture can be adopted, and diseased leaves, old leaves and yellow leaves should be removed promptly, which can reduce the breeding and food resources of green caterpillars and reduce their harm.

The above is an introduction to pest and disease control methods for rapeseed. We hope it helps you. For more related knowledge, please stay tuned to us.