Corn smut is also called Umi. It is an important disease of corn. Mainly harmful to corn tassels and ears, tassels infected, some of the entire inflorescence was destroyed and blackened, and some flower deformation and proliferation, glume increased and prolonged. When the ear is infested, the base is swollen, the tip is pointed and curved upwards, and the filaments are not drawn. The leaves are early yellow, split from one side, all become black powder, and the black powder disappears after the membrane breaks away. . Corn smut is only harmful to females and tassels, so that the diseased plants have no harvest.
In recent years, with the expansion of corn planting area in Horqin District, the number of maize varieties has increased, the resistance has decreased, and the corn fields in Horqin District are all spring irrigation fields, the ground temperature is low, and the source of corn smut in the soil is large. The smut is increasing year by year. According to the survey of the promotion center and grassroots agricultural technicians, the incidence rate of serious plot susceptible varieties is 8-10%, and the incidence of light plots is 2-3%. It is expected that smut will occur moderately in this area in this year, and local susceptible varieties will occur moderately.
Route of transmission and disease conditions:
The pathogens overwinter on soil, manure or seeds, becoming the source of infection at the beginning of the second year. Seed-borne bacteria are the main route for long-distance transmission. The pathogen can survive for 2-3 years in the soil, invading at the seedling stage, and is a systemic infection. When the corn is germinated after sowing, the germs also begin to germinate. From the white tip of the corn to the 4th leaf stage, they can invade, and grow into the flower buds and ears along with the growth of the corn, forming a large amount of black powder and becoming silky black ears. The continuous cropping period of maize is long, and the incidence of early sowing is heavy, the infestation temperature is 15-35 °C, and the suitable infestation temperature is 20-30 °C. Soil moisture content below 15% or above 30% is not conducive to disease.
Different varieties of maize have significant differences in resistance to head smut.
The severity of disease occurrence is closely related to the accumulation of bacterial sources. The incidence of continuous cropping is heavy, and timely removal of diseased plants and deep tumbling can reduce soil bacterial sources and reduce the incidence. The suitable temperature for the germination of chlamydospores is 27-31 ° C, lower than 17 ° C, higher than 32 ° C is not conducive to germination. Early sowing, low soil temperature and serious incidence. Drought at the time of sowing, the quality of sowing is poor, the soil is too thick, and the seedlings are unearthed, and the incidence is heavy.
Control method:
(1) Selecting resistant varieties;
(2) Appropriate late sowing to improve the quality of seeding;
(3) 2-3 days before sowing;
(4), rotation, deep turning;
(5) Coating with a seed coating agent containing diniconazole and tebuconazole.
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