Symptoms and prevention methods of corn rough disease [Map]
Corn rough disease is a corn virus disease caused by corn rough virus. The corn rough virus belongs to the plant reovirus group. It is a double-stranded RNA spherical virus with a double-layered capsid. Persistent mode of dissemination, corn rough disease is an important disease in the northern corn production area in China, let's take a look at the symptoms and prevention methods of corn rough disease!
The hazard symptoms of corn rough-reducing disease The mitochondria of corn are globular, with a passivation temperature of 800C, and can survive for 37 days at 20°C. The virus is transmitted by insects, and the main poisoning insect is gray planthopper, which is a persistent drug. The incubation period is 15-20 days. It can also infect wheat (causing blue dwarf disease), oats, millet, sorghum, valerian, etc.
1. Symptoms: Corn can be infected during the whole growth period, with the most serious damage in the seedling stage, 5 to 6 leaves can be manifested, and a transparent oil-immersed chlorotic dotted line is formed on both sides of the heart leaf and the midrib. Gradually spread the entire blade.
The diseased seedlings are thick green, the leaves are stiff, the width is short and thick, the heart leaves can not be unfolded normally, the growth of the diseased plants is slow, and the waxy white ridges are formed on the back veins of the dwarfed leaves, and the leaves are sharp and stiff with the hand touch. The leaves are dark green, the internodes are short and the top leaves are clustered like Clivia. The leaf veins of the leaf back, leaf sheath and eucalyptus leaves have waxy white strip-like protrusions of various thicknesses, which have obvious roughness.
In the 9th to 10th leaf stage, the dwarfing phenomenon of the diseased plant is more obvious. The upper internodes are short and swollen, the top leaves are clustered, and the height of the diseased plants is less than half of that of the healthy plants. Most of them cannot be sturdy and the individual tassels can be extracted, but There are very few branches and no pollen. The ear is abnormal, the filament is very small, the plant is seriously dwarfed, the tassel is degenerated, the ear is deformed, and it is not strong when severe.
2. Hazard: Since 1993, the occurrence of corn rough disease has increased significantly, causing great losses to the city's corn production. When it occurred in 1996, the rate of diseased plants in general ward was 40%, with an average reduction of 10% to 30%.
2007-2009 has occurred in the Huanghuai area for three consecutive years. How to control the damage of corn virus disease, especially corn rough disease (MRDV), has become a very practical issue. Therefore, in recent years, we conducted a systematic investigation on corn rough disease. The study found that 85.16% of the corn plants in the diseased plants were basically produced or discontinued, and the plant height was only 1/2 of that of the healthy plants, and there was no ear or ear without grain; 98.44% of the plants had a loss rate of grain weight. above 50.
3, characteristics: North China, the crude virus in winter wheat and other weed host winter. It can also be wintered in the body of poisoned insects. After the second year of corn was unearthed, the virus was transmitted to the corn seedlings or sorghum, millet and weeds by means of poisonous insects.
Maize is susceptible to disease before the 5-leaf stage, and the resistance is enhanced after the 10-leaf stage, even if it is affected by infection. If the corn emerges to the 5th and 10th stages, if it meets the peak of the migratory insects, the incidence is serious. Therefore, the corn sowing date is closely related to the incidence of the disease. For example, the corn planted in the middle of May in Hebei Province is in the first generation. The adult cockroach is in serious condition. The field management is extensive, there are many weeds, many gray locusts, and the incidence is heavy.
Prevention and cure method of corn rough disease
1. Agricultural control methods
In the prevention and control of corn rough disease, we must adhere to the comprehensive prevention and control policy focusing on agricultural prevention and control, supplemented by chemical control, the core of which is to control the source of poison, reduce the source of insects, and avoid the hazard:
1 Strengthen monitoring and forecasting: In the disease-prone areas, we will focus on the fixed-point, regular investigation of the rate and severity of crude disease and disease in wheat, field weeds and corn, and investigate the density and toxicity rate of Laodelphax striatellus. Before the end of autumn and late spring and corn planting, according to the wintering base and poisoning rate of the gray planthopper, the disease plant rate of wheat and weeds, combined with the corn planting mode, timely and accurate forecasting and forecasting of the occurrence trend of corn rough disease Prevention and treatment.
2 Choose the right variety: According to the local conditions, select the varieties with relatively good resistance, and pay attention to the reasonable layout to avoid large-scale planting of single resistant varieties. In the 1970s, Yu Nong 704 had certain resistance to the disease, 50, Ludan 053, Nongda 108, etc., and could replace the susceptible varieties such as Shendan 7, Qidan 53, and Shandan 22 in production.
It is particularly important to plant these varieties of resistant (resistant) diseases in areas where the susceptible varieties have been planted for many years and are seriously endangered. In Qufu City, the maize hybrids Ludan 50 and Luyuandan 14 are better resistant to rough disease.
3 Adjusting the sowing date of corn: According to the law of occurrence of corn rough disease, in the re-emergence area of ​​disease, the sowing date should be adjusted to make the corn most susceptible to disease during the growth period to avoid the emergence period of the gray planthopper and reduce the incidence rate. Spring sowing corn should be properly planted early, generally in late April in early May, corn in the wheat field is appropriately postponed, generally 5 days before the wheat harvest, try to shorten the symbiotic period of wheat and corn, and do the appropriate late sowing.
The corn planting mode in Qufu City mainly includes three types of wheat, corn, corn and late corn. The most serious disease is wheat, followed by corn, and corn for later. Spring sowing corn should be planted before the middle of April; summer sowing corn should be suitable in early June.
4 timely removal of weeds: roadside, field weeds are not only the source base of farmland weeds in the coming year, but also the wintering summer host of the corn-toothed disease transmission mediator. For the weeds remaining in the wheat field, the herb can be sprayed and then sprayed, and the herbicidal effect can reach about 95%. The advantage of choosing soil treatment is that the seedling corn does not coexist with weeds, which reduces the activity space of the gray planthopper, which is not conducive to the transmission of the gray planthopper.
5 Strengthen field management: Combine the seedlings, remove the diseased plants in the field, concentrate on deep burial or burning, and reduce the source of infection of rough disease. Rational fertilization, watering, strengthen field management, promote corn growth, shorten the period of susceptibility, reduce the chance of drug transmission, and enhance the resistance of maize to disease resistance.
6 Elimination of virus provenance: Maize rough disease virus mainly winters in wheat, grass weeds and Laodelphax striatellus. Therefore, it is necessary to control the wheat bush dwarf disease and remove the weeds on the edge of the field, the ground and the ditch. To reduce the base number of the gray locusts, the specific method is to spray with 25% of chlorpyrifos 50g/mu after the wheat is greened.
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 trace 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. Chemical control methods
1 Chemical dressing: coating and seed dressing of corn seeds with systemic insecticide can effectively control the gray planthopper in seedling stage and reduce the spread of rough disease. When planting, seed dressing with 2% seed coating agent can effectively prevent the damage of the gray planthopper, and at the same time, it is beneficial to cultivate strong seedlings and improve the disease resistance of corn. After sowing, the pre-emergence soil treatment agent such as 40% acetaminophen hydrogel suspension, 50% Dua mixture, etc., 550-575 ml/mu per mu, and soil sealing treatment of 30 kg of water are used.
2 spraying pesticides: in the field of corn seedlings with rough disease, it is necessary to remove the diseased plants in time, and according to the prediction of the situation of the gray locusts, use 25% of chlorpyrifos 50g/mu in time, and around the 5th leaf stage of corn. Spray once every 5 days, even 2 to 3 times, while spraying with 40% virus A500 times solution or 5.5% plant disease 800 times solution to prevent viral diseases.
For individual plots with poor soil treatment of herbicides before the seedlings, 20% of the herbicides can be sprayed between the rows of corn, 550 ml per mu, 30 kg of water, be careful not to spray on corn plants. On the top, the gram is quick-killing on weeds. After 52 hours of spraying, the weeds can all die, which can reduce the activity space of the gray planthopper. The field can spray 45% of the water, but in the corn line. Try not to use it to avoid phytotoxicity to corn.
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.
This article URL: Symptoms and prevention methods of corn rough disease [Map]
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