Soil improvement: symptoms and control of cabbage clubroot
Symptoms and control of cabbage clubroot
Nantong Shizhuang Chemical Co., Ltd. - Zhao Hongming
Plant disease: cabbage clubroot disease is caused by brassica campestris. After the plant is infected by Chinese cabbage root swelling fungus, its soil roots and underground stems will form tissue swelling tumors. In the case of slight impact, the appearance symptoms of the aboveground parts of Chinese cabbage are not obvious. In severe cases, the absorption of nutrients and water transportation of Chinese cabbage are interrupted, and the aboveground parts wilt due to malnutrition, showing varying degrees of yellowing. If the seedlings are young, some of them will droop, leading to premature death.
Chinese cabbage clubroot disease is a worldwide soil borne disease, which is widely distributed and causes losses of 10-15% worldwide every year. Some research data show that under the condition of being attacked by the cabbage root swelling disease, the yield of cabbage is usually reduced by about 20%, and in serious cases, the yield is reduced by up to 75%, or even no income, which can have a serious impact on the development of the cabbage industry.
Comprehensive utilization of high level rotation, adjustment of soil pH value, addition of calcium, boron and effective chemicals can effectively control cabbage clubroot. Although the use of resistant varieties has a certain timeliness, it can be more effectively controlled by combining with artificial means. At the same time, the use of harmful chemicals and high concentration compound fertilizers should be reduced as much as possible, which, on the other hand, ensures the balance of soil properties and ecosystems.
Symptoms: Irregular tumors of different sizes are formed on the main root or lateral root. The tumor surface is smooth at the initial stage, cracked and rough at the later stage. It is also easy to be infected with other bacteria and rotted. The main root grows slowly.
Pathogen: The pathogen lives in the soil for a long time and infects cabbage and other cruciferous plants through the soil. When preparing seeds, soil particles with bacteria attached to the seeds can cause seed infection. The development temperature of pathogenic bacteria is 9 - 30 ℃, and the optimum temperature is 20 - 24 ℃. The optimum temperature for spore germination tube and disease progress is 18~25 ℃. Acidic soil is conducive to the propagation of bacteria, while alkaline soil with pH above 7.2 is difficult to reproduce.
Occurrence rule: diseases caused by fungi. The pathogen goes through winter and summer with the diseased root in the soil, invades the host from the young root or wound, and spreads by rain, irrigation water and farm tools. In drought years, there are few diseases. The acid soil is seriously affected. The plots planted with cruciferae, the plots under the diseased fields and the plots with unmatured diseased manure are seriously affected.
Prevention and control measures: Longxin Mianlong is the first choice to thoroughly fumigate and disinfect the soil, with the dosage of 20-25kg per mu.
matters needing attention:
(1) Rotation with non cruciferous vegetables for more than 5 years. The seeds are selected from disease resistant varieties.
(2) Remove the diseased plants and carry them out of the field to burn or bury them deeply.
(3) Adjust soil pH,
(4) Strengthen management: timely watering and topdressing, intertillage and weeding during the growth period of Chinese cabbage to improve the disease resistance of the plant, and timely spraying Zhuangguanling can make the plant stem thick, leaves thick, leaves bright and tender, plants lush, and natural taste strong. At the same time, it can improve disease resistance, reduce the use of pesticides and fertilizers, and reduce residual toxicity.
(5) It often occurs in acid soil, land with high groundwater level and continuous cropping of cruciferous vegetables. When the temperature and ground temperature are 18~25 ℃, the disease is most suitable. Therefore, the cabbages sown or planted in August September were the most seriously affected. The late growth stage of spring sown Chinese cabbage is the disease occurrence period, so the damage is not serious. When cultivating Chinese cabbage in the diseased field, the plot that has not cultivated cruciferous crops for at least 5-6 years should be selected. The sowing date should be delayed as far as possible, and the seedbed and planting land should be disinfected. Strengthen drainage between fields and cultivate in high border.