In recent years, due to continuous cropping for many years in the vegetable production base near Chengdu, cruciferous root crops and root-knot nematode disease have become increasingly serious. The yield loss has been as high as 30% or more, and the root canker disease and root knot nematode disease have also promoted soft rot. Bacterial infections lead to poor crop development and wilting or even dead leaves. Symptoms of root club knot disease and root knot nematode disease are similar, and all show root swelling, poor growth on the ground, and the whole plant withered when severe. However, the two pathogens and disease conditions are different, and there are great differences in the prevention and control techniques. They need to be correctly identified and the right medicine should be prescribed. 1 Symptoms 1.1 The occurrence and symptoms of clubroot disease Cruciferous clubroot disease refers to the swelling of the main root or lateral root parenchyma caused by infection of the roots of cruciferous plants by plasmodiophorabrassicae Woron. At the beginning of the disease, the symptoms of the shoot were not obvious, and the growth gradually became sluggish, and the leaf color gradually faded out. Severe disease can cause the death of the whole plant. Clubroot disease occurs in the roots, and the root system is stimulated by pathogens. The cells accelerate the division and some of the cells expand to form tumors. Tumors are generally spindle-shaped, finger-shaped, irregularly deformed, large such as eggs, small as miliary. When the onset of the main root, the tumors are large and few, and when they occur on the lateral roots, they are small and numerous. The surface of the tumor is smooth at the initial stage, and cracks often occur later and are rough. The invasion of other bacteria can cause rotting. Tumors in the roots seriously affect the normal absorption of water and nutrients, so wilting occurs on the ground. However, in the late-sensible plants, the symptoms of the shoots were not obvious. 1.2 Root-knot nematode disease Root-knot nematode disease refers to the infection of root-knot nematodes from the roots of crops and is influenced by growth hormones such as indole acetic acid released by root-knot nematodes. The cells divide malignantly to form nodules or root knots. Mainly occurs in the fibrous roots and lateral roots, the disease Department produced fat swollen tumor-like knots. Cut open the root knot, inside there are many small milky white nematodes. A weak new root can be produced above the root, and when it is re-infected, a root-like tumor is formed. The symptoms of the lightly diseased plants were not obvious in the shoots, the serious diseased plants were short, the leaves were wilting, and they gradually turned yellow and dry. In severe cases, the whole plant died. 2 Transmission pathways and disease conditions 2.1 Club fungus Pathogenic fungi overwinter in soil or seed and can survive in soil for more than 6 years, mainly due to rain, irrigation water, pests, and agricultural operations. Bacteria can be developed at 9-23°C, suitable temperature is 23°C, suitable relative humidity is 70%-98%, and general low-pitched, acidic and calcium-deficient lands are heavy. 2.2 Root-knot Nematode Root-knot Nematodes Eggs and larvae live in the soil with plant diseases. They can be transmitted by seeds, seedlings, soil, flowing water, and packaging materials over long distances. Loose soil, high dry terrain and low salinity are suitable for root-knot nematode activity and have a severe onset. 3 Comprehensive Prevention and Control Techniques 3.1 Rotation of crop rotation can significantly reduce the condition of the disease. Areas where conditions permit can be used for paddy crop rotation, or with anti-resistant vegetables such as green onions, leeks, and peppers. 3.2 Choose seedling-free seedlings to choose uninfested plots as seedbeds, sterilize nursery soils, or use seedless plants such as peat, pond mud, and paddy soil. Sick seedlings in transplanted wards are prohibited. 3.3 Strengthen field management 1 tuberculosis is suitable for growth in partially acidic soils. The pH value of clubroot disease can be reduced by liming lime to increase the pH of the soil; and the cultivation and management can be enhanced. The stagnant water can be discharged in time and the diseased plants can be removed and brought out to burn. Sludge lime around the diseased hole to prevent the spread of fungus. The two knot nematode diseases are suitable for the growth of loose soil, high ground, and low salinity. The water flooding method can be adopted, ie, the summer season, deep-falling the soil, and high-temperature stuffy sheds after irrigation, and 10 to 15 days later. Kill the nematodes. And soil disinfection, that is, every 667 square meters with 10% full-library 5kg, ditch application or acupuncture, planting 3 to 5 days after site preparation. If a diseased plant is found, it should be removed promptly, destroyed centrally or buried deeply. 3.4 Chemical control 1 tuberculosis is treated with 15% Hymexazide 500 times solution or 70% thiophanate-methyl wettable powder 600 times solution rooted once every 7 days for 2 to 3 times. 2 root knot nematode disease can be used at the beginning of the disease 1.8% abamectin cream 2000 times, 50% phoxim EC 1800 times, 90% trichlorfon crystal 800 times or 80% dichlorvos 1000 times irrigate, 0.2-0.3kg per strain. In the growing season of vegetables, it is also possible to use 1% Haze extinction EC 80 times liquid surface spray control.
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