In recent years, vegetable fields, especially protective field nematode diseases have become increasingly serious, such as cucumbers, tomatoes, bitter gourd, carrots, beans, spinach, etc. will occur, due to the strong concealment of nematode disease, control difficulties, leading to farmers to reduce production and income losses, serious losses .
The main causes of nematode disease increasing year by year in vegetable fields are as follows: Firstly, one or two kinds of vegetables are grown for a long time, and the number of pathogenic nematodes continuously accumulates; second, nematodes are more harmful to the roots of vegetables; the aboveground parts show slow growth; the plants are yellowish and thin, and they are often considered as insufficient fertilizer and water. The problem was that there was no inspection and control of nematode diseases. Third, even if nematodes were found, the commonly used insecticides did not play a significant role in nematodes. In addition, greenhouse vegetable fields provide safe winter conditions for nematodes, which are also important conditions for the occurrence of nematodes.
1 symptoms
Vegetable root-knot nematode disease mainly damages the roots of plants. After the damage, a large number of root-knot neoplasias are formed in the roots, and the roots are atrophic. The root-transporting tissues are severely damaged or deformed, water and nutrients cannot be transported normally, and growth on the ground is hindered and growth is retarded. Debilitating, the plants are short, and the leaves are light in color, showing water deficiency, lack of fertilizer, and small old seedlings. Later, it became brown and the whole root was swollen and rough and irregular.
2 pathogens
The pathogen of vegetable root-knot nematode disease is mainly the southern root-knot nematode. The insect is male and female, the female adult is pear-shaped, the tip of the head, the abdomen is swollen, milky white, and visible to the naked eye. The parasite lives mainly in the host, resulting in the occurrence of pathological changes in the host tissue. For tumors, most of the worms are in root knots; male adults are linear, slender, slightly rounded at the tail, colorless and transparent, visible to the naked eye, and they mainly live in the soil near the roots, eggs are kidney-shaped or oval, after hatching. Larvae enter the soil.
3 the incidence of the law
The root-knot nematode lives in 5-10 cm soil layers, and adults or eggs live in the diseased root body or larvae in the soil. In the following year, overwintering larvae or larvae hatched from overwintering eggs invade plants from the roots, causing initial infection in the field. Tomatoes or cucumbers usually have root nodules at the early flowering stage. The flowering stage is the most, and the seedling stage is asymptomatic. Symptoms of leafy vegetables appear one month after transplanting. Diseased soil, diseased plants, or propagation of roots and tubers with nematodes, and diseased plant roots and stubbles are the major sources of pathogens and transmission routes. The environment generally suitable for the growth of vegetables is also suitable for the survival of nematodes. The development of nematodes is suitable for 15-30°C, soil moisture content is about 40%, and one growth cycle is 30-60 days. When the average temperature is 26C-30°C, a growth period is 21 days. Protected areas with heat sources can be affected all year round, and vegetables cultivated in the open season are peaking from June to August. Nematodes are aerobic, with high ground, loose soil, high water content, low salinity, neutral sandy loam, suitable for nematode activity, and heavy onset; soil is too moist and heavy, soil compaction, is not conducive to root knot nematode activity, The incidence is lighter. The soil is fertile, the seedlings are robust, and if the water and fertilizer are suitable, the disease is light; the land with long drought, no rain or uneven watering, and high soil moisture is favorable for disease. Long-term flooding of the onset of the plot can inhibit soil root-knot nematode activity.
4Temperature, gargle, farming system and the incidence of root-knot nematode
The low temperature in spring, late onset, slow and light, about 30 days after the colonization of vegetables, only sporadic onset; the high temperature in the fall, early onset, rapid, and heavy, can be lld after colonization. Spring worms are mainly affected by greenhouse diseases, which are mainly caused by high temperature in nursery greenhouses. In winter and spring, cucumbers and tomatoes are grown in greenhouses with high temperatures, and they are also affected. The greenhouse temperature of celery and pakchoi is relatively low: The summer and autumn greenhouses and greenhouses can all be diseased and heavy. The longer the continuous cropping period of the continuous cropping sites, the heavier the harm caused by nematodes.
5 Relationship between vegetable types and incidence
The occurrence of nematode disease is closely related to the types of vegetables. The degree of disease damage is roughly divided into three categories:
(1) Vegetables that are highly susceptible to onset are tomatoes, cucumbers, eggplants, celery, wax gourds, bitter gourds, melons, loofah, lettuce, and lettuce.
(2) Moderately sensitive vegetables include spinach, beans, carrots, fennel, cabbage, Chinese cabbage, and Chinese cabbage.
(3) Comparison of vegetables resistant to root-knot nematodes: peppers, sweet peppers, onions, garlic, leeks, etc.
Relationship between 6 nematode diseases and lack of fertilizer
Seen from the ground, nematode disease and malnutrition are indeed not easy to distinguish, and all show yellowing, leanness, and dwarfing, and the fruit cannot mature. Diagnoses must be rooted to observe. Most of the nematodes in vegetable fields in the north are root-knot nematodes, which cause tumors to grow on the roots of diseased plants, small grains like millet, large mung beans, round, spindly, or irregularly shaped, and they will rot later. Long tapeworm or other pathogens, but the first plant to infect the nematode.
7 Nematode Control Methods
The prevention and treatment of nematode diseases is difficult. Nematodes can tolerate many insecticides. Many of the effective pesticides in the past were banned from use because they are highly toxic to humans and animals or cause severe environmental pollution, such as carbofuran, methylisoprenophosphate, and g Phosphorus etc.
7.1 Agriculture and Physical Control
7.1.1 Implement strict quarantine of seedlings of plants to strengthen field sanitation, that is, to prevent the nematodes from passing through seed, seedlings, or soil manures to deliver concentrated deep-buried corpses.
7.1.2 High-temperature stuffy sheds use more than 55% of high temperature to kill nematodes, that is, after the land is ploughed, the chopped wheat straw is sprinkled with lime water and plowed for about 30cm. Then, the mulch is covered with water after irrigating and the greenhouse is sealed. More than 15d can kill nematodes. Plowing in winter before the north, without shelter in the winter, the use of low temperature to kill nematodes.
7.1.3 The implementation of a paddy-wheel rotation for onions, leeks, and pepper rotations, rotation for 1-2 years can also kill nematodes.
7.2 Chemical Control
Mu with 200 ml of “wireless†or “Line Cleaner†new biological agents diluted with water and flushed, can fully kill soil nematodes. Or use wireless fast-acting sustained-release granules 15009 or 20009 to mix or apply soil, which can not only form a stable and long-lasting protection ring around the roots, but also kill the nematodes and eggs around the roots to prevent the later infestation of soil nematodes.
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