Scientific control methods of rape root swelling disease

Rape, also known as rape, sowthistle, Latin name: Brassica campestris L. Cruciferae, Brassica plants, rape tender stems and leaves, native to China, its stem color dark green, such as Chinese cabbage, belongs to the cruciferous cabbage variety, the flowers are yellow. In agronomy, a number of species with oily seeds in plants are collectively referred to as rape. At present, the main cultivation types of rapeseed are Brassica napus (Brassica rapa (campestris) L.), mustard (Brassica juncea L.) and Brassica napus (Brassica napus L.). Mainly distributed in Anhui, Henan, Sichuan and other places. Rape is rich in nutrition, in which vitamin C content is very high. Rape generally grows in places where the climate is relatively humid, such as southern China. Rapeseed also has many uses, such as rape flowers can be eaten when they are not in bud; rape flowers are also a beautiful scenic spot when they are in full bloom (Hanzhong City, Shaanxi Province, China); after the flowers have withered, rapeseed can extract oil.

Classification of rapeseed varieties

Rapeseed cultivated in China can be divided into three types: Chinese cabbage type, mustard type and cabbage type.

Cabbage type

Rape is divided into small rape in northern China and Chinese cabbage in southern China. Small rape in northern China, small plant type, few branches, thin stem, undeveloped basal leaves, creeping growth, leaf-shaped oval, obvious piano-shaped lobes, and many spiny hairs. Qinghai-derived rape is covered with a thin layer of wax powder. Southern Chinese cabbage looks very much like ordinary pakchoi. Compared with the northern rape, the plant type is larger, the stem is stronger, the mesophyll tissue is loose, the basal leaf is developed, the petiole is wide, and most of them do not have wax powder. Suzhou Tibetan cuisine and Xinghua rape belong to this type. The petals of Brassica campestris are medium size, overlap each other, the growth period is short, and the number of somatic chromosomes is 10.

Mustard type

The plant type is tall, the branch is slender and the position is high, the basal leaf has obvious petiole, leaf surface wrinkles, with prickly hairs and wax powder. The flower is small, the petal is smooth, does not overlap, has the spicy taste, the somatic chromosome number is 18. Both fine-leaf rape and large-leaf rape belong to this type. Most of the rapeseed planted in Anshun, Guizhou are mustard type.

Cabbage type

The plant is of medium size, the leaves are thick and waxy, the leaf margin is deeply engraved, the upper part of the stem is sessile, the flowers are larger, the petals overlap, the seeds are larger, and there is no spicy taste. The chromosome number of somatic cells is 19. Victory rape, Oro rape and European rape all belong to this type.

Scientific control methods of rape root swelling disease

Harmful symptoms of rape root swelling disease

The symptoms of rape root swelling disease appear in the root, these "tumors" are spindle-shaped or irregular deformities, mainly on the main root, less on the lateral root. In the initial stage, the surface of the "tumor" is smooth and white, and then the color will gradually turn brown, the surface is rough, and cracks will appear over a long period of time. These cracked "tumors" are easily infected by other bacteria and rot and stink. In the early stage of the disease, at noon, due to the high temperature, the transpiration of rape increased and lost a lot of water, and at this time, because the root was damaged by the "tumor", the ability of absorbing water and fertilizer had been reduced, so in the case of lack of water, the aboveground part of the diseased plant is prone to wilting; when the temperature is low in the morning and evening, the transpiration of rape is small and water loss is less, so it will not wilt. As the disease continues to deteriorate, the diseased plant will wilt completely and even die.

Scientific control methods of rape root swelling disease

1. Prevention. For the prevention and control of rape root swelling disease, we should start with cultivation and management, put an end to or reduce the number of bacteria in rape field from the source, and create an environment conducive to rape growth but not conducive to pathogen growth.

Methods: rape seeds were not transferred from disease areas, and other non-cruciferous crops, preferably with rice rotation, were rotated for 4 to 5 years in seriously diseased fields, which could effectively reduce the disease. build drainage facilities in rape fields, deep ditches and narrow beds, clear ditches and prevent stains, and reduce soil moisture; avoid planting rape in low-lying waterlogged plots or acidic soil; fly ash compound fertilizer can be used to improve soil. Select the field without this disease to raise seedlings to prevent the spread of germs. The diseased and residual plants should be burned or composted after harvest. Note: compost must be ripened before it can be used in rape fields. Take the above measures, can reduce a lot of incidence of disease, but not no longer.

2. Governance. When a small number of root swelling plants appear in the field, the diseased plants need to be pulled out in time, and quicklime is scattered in the disease hole to disinfect the soil. If there are more diseased plants, the root can also be irrigated with 50% carbendazim wettable powder 500 times solution, 250 ml per plant, or 40% pentachloronitrobenzene powder 500 times solution, 400 ml per plant, which can also effectively control the disease.