What are the rules of maize dwarf mosaic disease?

The virus mainly overwinters on the host of perennial gramineous weeds in the field and is the main primary infection source. When the conditions are suitable, aphids get viruses from host plants with viruses in winter and migrate to corn to feed and spread the viruses. Infected plants become the center of the virus source in the field, and spread the virus to the whole field with the feeding activities of aphids, and spread the harm to corn and weeds in spring and summer. After corn harvest, aphids spread the virus to weeds for the winter.

The occurrence and prevalence of the disease are related to the disease resistance of varieties, the virus-carrying rate of seeds, the source base of overwintering viruses, the number of aphids and climatic conditions.

The difference of disease resistance between maize inbred lines and varieties to MDMV may be related to the aphid resistance among varieties and the disease resistance mechanism of maize itself. Maize seeds can spread MDMV, and the higher the virus-carrying rate of seeds, the higher the field incidence. The virus-carrying rate of Yedan 2 seed can reach 3.09%, and the virus-carrying rate of Mo 17 inbred line can reach 2.35%. Generally, overwintering weeds have many hosts, high virus source base, high density of aphids, high probability of virus transmission in spring, heavy disease in spring corn and heavy disease in summer corn.

The incidence of summer maize is also directly affected by viruses on field host plants and weeds, especially at the seedling stage of summer maize, which is the peak of aphid migration in wheat fields. The number of virus sources on various host plants has increased, so summer corn is more seriously affected than spring corn.

Climatic conditions mainly affect the population number of aphids and the activities of virus-transmitting aphids. Generally, during the migration period of aphids, there are many times of rainfall, heavy rainfall and low temperature, which are unfavorable to the reproduction and migration of aphids. At the same time, the growth and development of maize is robust, the disease resistance of plants is enhanced, and the occurrence of diseases is light. On the contrary, long drought without rain, dry and hot weather, rapid reproduction of aphids and frequent migration activities are conducive to the occurrence of diseases. When the body temperature is above 28℃, the symptoms are relieved or hidden. The symptoms below 16℃ are not obvious or asymptomatic.

In addition, the disease of early sowing corn in spring and summer is lighter, and the disease of late sowing corn is heavier. The plots with fertile soil and strong water retention are slightly ill; Sandy soil and barren land with poor water holding capacity are seriously ill; Diseases with few weeds managed well in the field are light, and diseases with extensive management are heavy; The disease of interplanting field is lighter than that of monoculture field.