First, symptoms of smut
Maize smut is a local infestation disease with a long infection time and can infect corn at seedling stage to maturity stage. At the onset of seedling stage, small nodules are formed on the base of the stem near the ground or on the back of the leaves, and blackish aneurysms in the base of the stem expand more. When severe, the seedlings may die. Plant diseases are most seriously affected by the ear, and when the disease occurs, the upper half or individual grains of the ear produce nodular bacillary dysentery. In severe cases, the whole ear forms malformed bacillary dysentery, which is white at first, later grayed, and later formed white gray. To the dark gray film, after the film ruptured, black-gray powder (ie, teliospores) was emitted, and the teliospores germinated immediately and reinfected. Maize smut disease in Hebei Province is dominated by adult plant diseases, with less incidence at the seedling stage.
Second, the incidence of the law
The bacterium used winter spores to overwinter in the soil and the sick. Became the first year's first dip source, composting mixed with diseased bodies is also one of the primary sources of infusion. In case of drought before and after corn tasseling, it can not be timely irrigated, often causing corn physiological drought, reduced turgor pressure, weaker disease resistance, which is conducive to the spread of germs and disease. The high temperature and humidity in the field are prone to condensation, and after the storm, it causes a lot of damage and can cause serious illness. Continuous cropping and high-fertility planting are often severe.
Third, prevention and control methods:
1. Planting resistant varieties
Planting disease-resistant varieties is the most cost-effective method of prevention and control, and it is also a problem that smut control must solve. Seed management and promotion units should strictly control seed quality and prevent the promotion of cultivars with poor smut resistance in our province. At the same time, in light of the characteristics of smut, the variety distribution work should be done well. In areas where smut infection is serious, actively promote disease-resistant varieties and eliminate susceptible varieties as soon as possible. As a breeding unit, the identification of anti-aridenic materials and varieties should be strengthened.
2, according to local conditions, a reasonable rotation
Rotation is an effective measure to reduce the amount of bacteria in the field. From the standpoint of the incidence of smut, the incidence of continuous cropping is severe, and the incidence of crop rotation is significantly lighter. Therefore, the actual situation is based on rational crop rotation and avoids continuous cropping for many years. According to the characteristics of pathogens surviving in the soil for more than two years, a three-year rotation cycle can be used. Variety rotation can also play a preventive role, avoiding planting the same species for many years in the same plot.
3, seed treatment
Seed-borne seeds are the main source of infestation of smut, especially long-distance transmission. Seed dressing or seed dressing can not only inhibit the pathogenic bacteria that the seeds carry, but also have some preventive and control effects on the germination of the seeds. At present, there are many kinds of coating agents and seed dressing agents used in production and application. It is necessary to choose agents with strong absorption and long residual effect to be used for seed dressing. Generally, 25% triadimefon EC may be used for 1000 ml, 25 kg seeds may be mixed, or 0.2 In the case of seed dressing with a copper sulfate solution, 50% thiophanate-methyl may be used to seed the seeds at 0.3% of the seed amount to reduce the hazard.
4, strengthen field management
Timely sowing, appropriate depth and depth of sowing, promote seedlings early, reduce the chance of infection. Closely plant the plant, cultivate strong seedlings, and enhance the resistance of the variety. Strengthen the management of fertilizer and water, pay attention to the application of nitrogen, phosphorus and potassium to avoid partial application of nitrogen fertilizer. Irrigation should be timely, especially before and after tasseling, to ensure water supply. Timely control of corn borer, minimizing insect damage and farm machinery damage. When a diseased plant is present in the field, it is removed in a timely manner in the early stage, taken away from the field, and bacillary dysentery is removed early and later to reduce the source of re-infestation bacteria in the year and the source of bacteria in the following year.
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