Maize rough dwarf disease is a viral disease caused by the corn roughage virus. In recent years, the disease has shown a clear upward trend in some areas of our province, which has become an important disease in corn production and poses a serious threat to corn production. First, the onset of symptoms In the early stages of the development of corn rough dwarf disease, transparent dotted spots appeared on both sides of the midrib of the base of the heart, and then gradually spread to the entire leaf. The leaf veins, leaf sheaths, and temporal lobes of the diseased plants have waxy white sticks on the veins, and there is a noticeable rough and uneven feeling by hand. The leaves are short and wide, thick and stiff and stiff, with dark green leaves and clusters of top leaves. The growth of diseased plants was inhibited, internode swelling and shortening, and severe dwarfing. The root system is small and short, less than half of the strong strain, and it is easy to pull up from the soil. The mildly diseased plants have poorly developed tassels, less loose powder, shorter ears, less filaments, and less strong seeds. Severely diseased tassels cannot be extracted or can be extracted but with few branches, no pollen, and false or abnormal grains. Second, the pathogen and the spread of corn rough dwarf disease pathogen is the corn roughage virus. Its host range is very broad, mainly monocotyledonous grasses, which can infect corn, wheat, rice, sorghum, millet, barley and other crops, as well as grasses such as crabgrass, barnyardgrass and teff. The virus is mainly transmitted by the planthopper in a persistent manner. Once it is poisoned, it will be poisoned. The virus can live over winter wheat, perennial grasses and virus mediators. In the spring, the first adult of Laodelphax striatellus feeds on wintering hosts and gradually migrates from wheat to corn, forming a migration peak during wheat harvest. The second, third and fourth generations of Laodelphax striatellus were mainly on corn and field weeds. As maize matured, it was moved to alfalfa. After the emergence of autumn wheat, the 4th generation of Laodelphax striatellus was transferred to wheat field and transmitted to wheat. Overwintering, forming an annual cycle of infestation. Third, the incidence of conditions, toxicants, mediators, corn susceptible varieties are three necessary conditions for the occurrence of the disease. When the source of poisons accumulates to a certain extent and there are enough mediators and susceptible varieties, it may cause the disease to become epidemic. The growth and propagation of mediators, the number of populations and climatic factors, and the host plants are closely related. Whether the variety is susceptible to planting varieties is also related to environmental conditions and developmental stages. 1, the amount of toxic source. Perennial grass crops and weeds are the host plants of the corn roughage virus, so in the production, corn fields with extensive management and weeds are more severe than those with fine management and less weeds. In the case of severe crops with severe clusters of wheat dwarfs, the incidence of heavy crops was heavy. This is due to the presence of maize rough dwarf virus in wheat bush dwarf disease strains, and they are all caused by the poisoning of SBPH. 2, corn cultivation mode. The degree of susceptibility to disease in different growth stages of maize varies greatly. The earlier the disease is felt, the heavier the condition is. There are less spring corn in our province, most of the summer corns are wheat intercropping, and the symbiotic period of wheat and corn is longer. This cultivation mode is beneficial to the disease. The emergence of corn to the 7-leaf stage is a sensitive growth period for the disease. Most of the wheat crops were sown in late May. The sensitive growth period coincided with the first generation of adult migratory locusts, which is the peak period of transmission. At this time, the corn sown after harvesting had not yet emerged, and escaped the peak of transmission and infection. The average spring maize and wheat corn are heavy, and the summer live corn corn is light; while the wheat corn and summer corn are sown early and lightly sown late. 3, corn varieties disease resistance. At present, most of the varieties planted are highly susceptible or susceptible to viral diseases, with few resistant varieties and fewer highly resistant varieties. Therefore, once the number of viral mediators increases, it will promote the epidemic. Fourth, comprehensive prevention technology for the prevention and treatment of the disease should adhere to the main prevention and control of agriculture, chemical control, supplemented by comprehensive prevention and control strategies. The core is to control the source of the poison and to suppress the source of the insects, so that the corn will avoid the dangerous period of the susceptible period of the crude contracting virus to avoid the transmission of poisonous adults of S. macrophylla. 1. Selection of resistant varieties, suitable sowing Although there are currently no resistant varieties in the main cultivars, there is a difference in resistance between cultivars. According to the local conditions, we can use varieties with relatively good resistance, such as Nongda 108 and Dandan 21, etc. We can compress 478 series and 107 series hybrids such as Xiyu No. 3, Dandan No. 13 and Dandan No. 2 etc. Variety. At the same time, reasonable layout should be taken to avoid large-scale planting of a single source-resistant variety. According to the law of disease, corn is most susceptible to the seedling stage. The sowing date should be adjusted as far as possible so that the seedling stage of corn seedlings avoids the peak of the transmission of SBPH. For the summer corn, wheat seedlings should be interplanted as much as possible, even if interplanting, the symbiotic period of wheat and corn should not be more than 7 days. Vigorously promote the sticking of live broadcast or harvesting of wheat after harvesting. 2. Remove weeds, control poisonous sources, remove diseased plants, strengthen field management, remove corn field and weeds in time, and destroy suitable habitats for SBPH. Combining seedlings with seedlings, timely removal of diseased plants in the field, brought out of the field burned or buried. Rational fertilization and watering, strengthen field management, promote robust growth of corn, shorten the period of disease, reduce the chance of transmission, and enhance the resistance of corn to disease resistance. 3. Chemical control eliminates transmission of virus mediators Laodelphax striatellus is an effective method to prevent and treat this disease. 1 Chemical dressing or coating. Insecticides or coating agents used for dressing or coating, can effectively control the seedling stage of planthoppers, reduce the spread of disease; 2 spraying insecticide at seedling stage. Before and after corn sowing and during the seedling stage, controlling spraying of corn plants in the corn field and nearby weeds has a certain effect on reducing disease. 10% imidacloprid can be used, spraying should be uniform and thoughtful to ensure control effect. In the early stage of corn rough disease, 20% of virus A wettable powder or 1.5% of diseased planting spirit can also be used for prevention and treatment, and the effect is also ideal.
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