Controlling Laodelphax striatellus to prevent corn rough disease

Controlling Laodelphax striatellus to prevent corn rough disease

Maize rough disease (MRDV) was severely affected in some parts of China in the 1960s and 1970s. In recent years, the northern provinces of Yunnan, Shandong, Shaanxi, Shanxi, Liao, Tianjin and other provinces have exploded. In 1997, there were more than 2.33 million hm2 in the country, which seriously threatened the development of corn production. The reason: First, the corn variety does not resist disease. The second is the interplanting of corn and wheat or the arrangement of cotton, vegetables, etc., and the roughening disease spreads to the cotton fields in the cotton and vegetable areas. Third, the growth period of corn disease is consistent with the high growth period of the gray planthopper, which is an important reason for the current corn planting system to facilitate the prevalence of crude disease. Fourth, warm and dry winters and less rain in spring are favorable weather conditions for the disease.
First, the occurrence of corn rough disease
1. The process of virus infection. The maize rough-reducing virus is mainly transmitted by the gray planthopper in a persistent manner. The virus and its mediator, the host of the plant, are widely distributed, mainly monocotyledonous plants, such as wheat, rice, corn, sorghum, millet, barley and other crops, as well as looking at Mai Niang, dog tail grass,
Weeds such as crabgrass, valerian, and thrush. Corn is not a favorite host of the sphagnum. When there is no suitable host in the field, the locusts use corn as a transitional host for parasitic reproduction. Wheat bush dwarf disease and rice dwarf rice disease are also infested by maize rough-reducing virus, and wheat clump dwarf disease strain is the main initial infection source of maize rough disease.
2. The annual alternation of the gray planthopper and the occurrence of corn rough disease. In the north of the Huaihe River, the gray locusts generally winter on the grass weeds such as wheat fields and wheat maidens in the third and fourth nymphs. They emerged as adults in March and April, and continued to breed on the wintering hosts. From late May to early June, when the wheat harvested, the first generation of adult worms emerged, forming a peak of migration, moving into the spring rice field and the single-season late rice field, and the summer in the rice field continued to be harmful, generally lasting 3 to 4 generations. In the corn area where there is less paddy field, when it is harvested, it is mainly moved into the corn field and grass weeds and is more summer. This is the sensitive period of summer corn disease.
It is often caused by a large outbreak of corn, and the first generation of gray planthoppers is a serious hazard to corn.
After harvesting corn and late rice, they migrate to grass weeds. After the emergence of autumn wheat, the wheat is transferred to the wheat field and poisoned and overwintered to form a disease cycle throughout the year.
3. The disease resistance of corn. The disease resistance of maize seedlings is strong, and it is highly susceptible to disease in 2 leaves and 1 heart. The disease resistance is enhanced after jointing. The disease after 10 leaves generally has little effect on yield. Practice has shown that in the northern corn region, the incidence of spring maize planting after mid-April is heavy, and the later the sowing date, the heavier the disease. Summer corn is ill with wheat hull corn, and the live broadcast is light, and it is heavy in early sowing and light in late sowing.
4. The prevalence of corn rough disease. In the northern corn producing areas of China, the area of ​​wheat is large, rice is also widely planted, and the existence of grass weeds provides a rich source of poison and a good mediator of the virus mediator. surroundings. At the same time, the cultivation of northern corn is mainly based on summer maize, and the use of wheat ridge interplanting and post-harvest no-till seeding is often used. The corn seedling stage often overlaps with the peak of the first generation of the gray planthopper, and the disease resistance of the corn seedling stage is extremely weak, which provides a favorable opportunity for disease infestation. If the winter is warm, the spring is dry, and the summer rain is suitable, it is suitable for the wintering and breeding of the gray planthopper. The first generation of gray planthoppers occurs, which causes a large outbreak of corn rough disease.
Second, the field symptoms:
The diseased strain of corn is seriously dwarfed, only l/2-1/3 of the height of the healthy plant, and it can develop after emergence. However, symptoms appear only at 5-6 leaves. The disease first appears transparent dotted spots on both sides of the midrib of the heart leaf, and then gradually spreads to the whole leaf, and produces waxy white protrusions on the leaf veins of the leaf back, and the leaves are dark green. The width is short, hard and brittle, and it is opposite to the raw shape. Sometimes the sheath and the leaves of the ear are covered with waxy white streaks. The roots of the diseased plants are not developed and are easy to pull out. Although the light is sturdy, but the half is wrapped in the bell mouth, the tassel is aborted or stunted, the filament is not developed, the fruit is less, and the seriously ill plant is more dead or not harvested. In addition to harming corn and sweet corn, the disease can also harm barley, wheat, oats, sorghum, millet, etc. The symptoms are similar.
Third, the prevention of corn rough disease The occurrence of corn rough disease is completely caused by the infection of the poisonous gray planthopper, so eliminating or avoiding the spread of gray planthopper is an important way to prevent the occurrence of corn rough disease. Therefore, the following measures can be taken to prevent it.
1. Remove weeds in the field. The maize rough disease virus mainly winters in wheat, grass weeds and Laodelphax striatellus. Therefore, we must do a good job in the prevention and control of wheat bush dwarf disease, remove the weeds on the edge of the field, the ground and the ditch, and at the same time reduce the number of the fly locusts. The specific method: after the wheat is green, use 25% of the scorpion 50g/mu , 50% monocrotophos 5000 times liquid spray. When spraying, the weeds around the wheat field should also be sprayed, which can significantly reduce the density of the insects. If necessary, 20% gram of traceable water or 45% of the water agent 550 ml/mu, 30 kg of water, Spray on the fields at the edge of the field to kill weeds in the fields and destroy the living environment of the gray planthoppers.
2. Control wheat field fly ash and reduce the transmission of poisonous media. Winter wheat in the wheat field, eliminating the winter nymphs of the gray locusts, using the herbicides such as DuPont superstars to control the weeds in the wheat field, and combining the wheat in the early spring with the joint treatment of wheat to prevent and cure the wintering adults; after the wheat heading, combined with disease prevention and control, the first generation of gray planthoppers.
3. Adjust the corn sowing date. In order to avoid the peak of the flyover and facilitate chemical control, summer sowing corn should be concentrated in the end of May and early June, and the intercropping should be about 7 days before the wheat harvest. After the good wheat, the live broadcast or smashing seeding; spring corn Sowing should be carried out in advance in early April to avoid the peak period of overwintering adults.
4. Corn field management. (1) Seed dressing with phorate and carbofuran seed dressing; or seed dressing with 0.2% to 0.3% of seed amount with phorate; or use 3% carbofuran granules with caves, 1.5 parts per 667m2 ~2kg, the efficacy of the Laodelphax striatellus can last for more than 30 days. (2) Before and after corn planting and seedling stage, spray insecticides on corn fields and nearby weeds to control the brown planthopper. Commonly used agents are: 80% dichlorvos EC, 40% omethoate EC, 40% monocrodo emulsifiable concentrate, 50% phoxim EC, 50% methamidophos EC; special agent: 2% rice bran net Wettable powder, 50% balsa emulsifiable concentrate. Virus A, Phytophthora (3) seedling stage, should promptly remove the diseased plant, bring out the field to burn out, properly delay the seedling time, and use 1.5% phytopathogenic 800~1000 times before the corn 3 leaf stage, 20 % virus A500 times spray can effectively reduce the occurrence of diseases. (4) Adding organic fertilizer; N, P, K, and micro-fertilizers are reasonably matched; timely cultivating loose soil; when corn grows to 5-6 leaves, spraying foliar treasure, spraying Shibao, plant power, etc. Promote the robust growth of corn, improve the disease resistance of the plant itself and the disease resistance after the disease, and control the damage caused by the occurrence of rough disease.
Corn rough disease is devastating. Once it happens, it is difficult to cure. It is unrealistic to spray a certain agent on a diseased plant to restore it to normal. But as long as the combination of agricultural control and chemical control is achieved, the ring is tight. If you buckle, you will be able to control the spread of its hazards.

Linyi County Agricultural Bureau Plant Protection Station
Linyi County Agricultural Bureau Seed Management Station Linyi County Fonongmen Seed Industry Service Center
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