Corn dwarf mosaic disease occurs in all corn-producing areas in my country. The disease is caused by the maize dwarf mosaic virus (MDMV). In addition to damaging corn, it also infects sorghum, millet and other crops and hybrid crops. Grass. Corn dwarf mosaic disease can occur in the entire growth period of corn, and the damage is more severe in the seedling stage. At the beginning of susceptible plants, many oval, chlorotic dots or spots appear between the veins at the base of the heart leaves, arranged into intermittent stripes of varying lengths along the veins. As the disease progresses, wider chlorotic stripes form on the leaves. It is especially obvious on new leaves. The leaf color turns yellow, the tissue becomes hard, and the texture is brittle and easy to break. In some cases, purple-red stripes appear starting from the leaf tips and edges, and finally dry up. The diseased plants are yellow, weak and thin, grow slowly, and most of them fail to head and die. Although a few diseased plants can heading, the ears are small, the seeds are few and thin. The roots are susceptible to rot.

The initial infection source of corn dwarf mosaic disease comes from perennial grass weeds. In early spring, after overwintering aphids revive, they feed on the newly grown tender leaves of poisonous weeds and obtain the poison. , the virus-carrying winged aphids spread the virus to corn when they migrate, harming spring and summer corn, causing disease epidemics. After the summer corn is harvested, aphids return to weeds to overwinter. From June to July, if the weather is dry, it will not be conducive to the growth and development of corn, but will be conducive to the reproduction and migration of aphids, which will cause severe disease. Late sowing of spring corn and early sowing of summer corn both resulted in severe disease.

Prevention and control methods:

① Agricultural measures: First, select disease-resistant inbred lines and plant disease-resistant hybrids; second, sow spring corn at the appropriate time and early to avoid disease and increase yield; The third is to strengthen field management and increase the disease resistance of corn itself; the fourth is to remove diseased seedlings and plants in a timely manner to reduce sources of reinfection.

②Chemical control: First, promptly eliminate aphids on surrounding weeds in early spring. When aphids migrate to the peak of the wheat milk-ripening stage, promptly spray 3% tiandacetamiprid or 2.5% high-efficiency chlorofluoride Use 1,500 times of cymethrin, or 3,000 times of 2% abamectin, or 5,000 times of 25% Acta for prevention and control; second, spray "Tianda 2116" and related pesticides to prevent viruses in a timely manner. Spray 1500 times of Tianda Yufeng (or 1500 times Shengzhifeng) liquid + 600 times of "Tianda 2116" special liquid for strong seedlings at the 3-4 leaf stage; spray 600 times of "Tianda 2116" special liquid for grain growth at the 6-8 leaf stage. Tianda 2116" liquid + 1500 times Tianda Yufeng liquid has good control effect.