From June 15 to July 10, 2004, during the agricultural technical consultation activities, the author received more than 100 farmers who took the corn to the office to consult and asked why the corn grew into lettuce. The corn they saw was short and thick, the internodes were shrunken, the dwarfing plants were less than half of the healthy plants, and the leaves were dark green. They were concentrated in rapeseed pods and early sowing mash, and farmers complained that they were seed problems. According to the author's multi-point investigation, the county's plots account for more than 45% of the summer sown maize, about 867 hectares, and the varieties are Yudan 18, Denghai 9, Denghai 11, Tongji 100, Zhongke. No. 4 is heavy. In Gushan Xiang, Dushan Township, a survey of 2,668 acres of Dandan 18 occurred, and the occurrence of corn stubble was not over 56%. Half of the plots are around 36-40%, and lighter ones are between 13-17. Some of these varieties or late-seeded wheat stubble corn appear to be lighter. So what causes corn to grow like lettuce? First, the reason analysis: After the multi-point investigation and field identification, the phenomenon of distribution of the above-mentioned phenomenon has a wide range (the county has occurred in 18 townships), many varieties (the county's main push varieties in addition to a few varieties are all susceptible), fertility During the period of concentration, it is mainly concentrated damage of rapeseed meal and early wheat, and the basic elimination is the quality of the variety. Experts believe that the main reason for the dwarfing and thickening of corn is that the rapeseed glutinous corn and early seeding buckwheat maize are infected with the RBSDV virus at the seedling stage. The virus-infecting insects are mainly Laodelphax striatellus, which is caused by fly ash. Scorpion spread virus induced corn dwarf disease is not long, has nothing to do with the quality of the species. Second, the influencing factors: Although the exclusion of the species is not the main cause of the disease, but the disease still shows a significant difference in the field, that is linked with some external conditions, specifically: 1, disease-intensive varieties of disease incidence. After a number of investigations, the hybrids selected in the hard grain corn inbred lines promoted by the county have a lighter incidence, and the dentate and silty corn varieties are heavy, such as Zhongke No.4, Denghai 11, and Shandan. The rate of diseased plants, such as 18, was about 23%, while that of Jidan 7 and Nongda 108 was light. 2. Warm winter is the inducement: In 2004, the county was warm and dry in winter, which was 2-3°C higher than the normal temperature in the normal years, and it was dry and rainless in January-March. It was conducive to the overwintering of virus mediators, combined with more summer rainfall, and the temperature was suitable for gray. Fly trout breeds and transmits poisons. 3. The planting system is diverse: the area of ​​protected areas has increased, the multiple cropping index has been increased as a source of poisons, and the virus-mediated mediators have provided more favorable sites for winter, which is conducive to the survival and reproduction of the mediators and transmission of drugs. 4. Related to the development stage of corn: The disease was concentrated during the period of time. The target fields were mostly rapeseed, waxy corn and early sowing, wheat, corn, and corn. The late sowing of corn in spring and wheat was significantly lighter, mainly in the stage of corn growth before the five-leaf stage. The immune system is weak, and the large scale infestation at this stage happens to be the cause of contagion. Third, prevention and control measures. The incidence of corn rough dwarf disease was relatively light in our county. Farmers lacked awareness and the disease was a viral disease. Once the disease became difficult to cure, it advocated prevention. 1. Prevention and control countermeasures: If you choose Jindan No. 7, Nongda 108, Dongdan 60, and Daiyu No. 4 and other varieties, while susceptible varieties such as Dandan 18, Denghai 11, and Tongji 100, do not use rapeseed meal and early sowing. use. 2, seed coating or seed dressing. Laodelphax striatellus is a virus-mediated mediator that causes corn rough dwarf disease. Using seed dressing to apply pesticides with a long residual effect period can effectively kill the virus-borne mediator and reduce the chance of infection. 3, spraying prevention: in the summer sowing of corn after sowing a net to control the sneeze larvae breeding, there is inhibition of the disease. 4, in addition to timely removal of diseased corn field, can reduce the source of poison. After the onset of the disease, 200 ml of bacteriocin was sprayed, 50 kg of water was sprayed, and sprayed once every 5 days. This has obvious control effect on this disease. (Anhui County, Anhui Province, Agricultural Technology Promotion Center, Wang Jiashan, Zhang Qin)
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