What are the symptoms of corn dwarf mosaic disease,

Corn dwarf mosaic disease occurs in all maize producing areas in China, and the disease is caused by maize dwarf mosaic virus (MDMV), which not only harms maize, but also infects crops and weeds such as sorghum and millet. Dwarf mosaic disease of maize can occur in the whole growth period of maize, and the damage at seedling stage is more serious. At the beginning of the susceptible plant, there are many oval, faded green dots or markings between the leaf veins at the base of the heart leaf, which are arranged into intermittent and different length points along the leaf veins, and the disease develops further, and a wide faded green stripe is formed on the leaves, especially on the new leaves, the leaf color turns yellow, the tissue becomes hard, and the texture is brittle and easy to break.

Some start from the tip and edge of the leaf, appear purple-red streaks, and finally dry up. The diseased plants are yellow and thin, grow slowly, and most of them cannot be headed and die. Although a few diseased plants can be headed, the panicles are small, the seeds are few, and the seedlings are thin.

The root system is perishable.

In early spring, after the overwintering aphids are revived, they feed on the young leaves of the newly grown poisonous weeds and obtain the virus, and the poisonous winged aphids will spread the virus to the corn when they migrate, harming spring and summer corn, causing the epidemic of the disease. After the summer corn is harvested, the aphids return to the weeds to overwinter. From June to July, if the weather is dry, it is not conducive to the growth and development of corn, but is conducive to the reproduction and migration of aphids, and the disease is serious.

Late sowing of spring maize and early sowing of summer maize were serious.

Prevention and control methods: agricultural measures: first, select disease-resistant inbred lines and plant disease-resistant hybrids; second, spring corn is sown early at an appropriate time, which can avoid diseases and increase yield; the third is to strengthen field management and increase the disease resistance of corn itself; Fourth, remove diseased seedlings and diseased plants in time to reduce the source of reinfection.

Chemical control: First, in early spring, eliminate the aphids on the surrounding weeds in time, and spray 3 days of acetamiprid, or cyhalothrin 1500 times, or 2 avermectin 300 times, or 25 Acteta 5000 times when the aphids are at the peak of migration; The second is to spray "Tianda 2116" and pesticides related to virus prevention in a timely manner. Seedlings were sprayed at the 3-4 leaf stage with 1500 times Tianda Yufeng (or 1500 times Shengzhifeng) liquid 600 times "Tianda 2116" special type of medicine solution for strong seedlings, and 600 times at 6-8 leaves sprayed with 1500 times of Tianda Yufeng liquid medicine for grain, and the control effect was good.

Occurrence and prevention of maize roughage disease.

In recent years, with the adjustment of planting structure and the influence of climatic factors, the occurrence of maize roughness disease has become more and more serious, and it has become one of the important diseases affecting maize production. At present, spring-sown corn is about to be sown, and in order to effectively control the occurrence of corn roughness disease, it is hoped that the vast number of farmers will make preparations for prevention and control as soon as possible.

1. Symptoms: Corn roughness disease is a devastating viral disease transmitted by gray planthoppers. Corn can be susceptible to the disease after emergence, and symptoms only appear when there are 6-7 leaves.

The diseased plants are dwarfed, the internodes are shortened, the leaf color is dark green, the whole plant or the top is clustered, most of them can not be headed, and the plants with late onset can also be headed, but the fruit ears are less deformed.

2. Pathogenesis:

1. The amount of poison source. A variety of grasses and weeds are the host plants for maize roughage disease. Corn fields with more weeds and extensive management are more likely to develop the disease than those with fine management and few weeds.

2. Corn sowing date. Early spring sowing (early and mid-April) and wheat stubble and maize (sown after mid-June) had few diseased fields, and the disease was mild. Sowing around mid-May is severe. The main reason is that from mid-May to early June, the first generation of adult planthoppers is at its peak.

At this time, there are few tender green plants in the field, which can cause concentrated damage to gray planthoppers.

3. Corn leaf age. From the seedling stage to the 7-leaf stage, the sensitive leaf age of maize rougher shrinkage disease is the sensitive leaf age, and the safe leaf age stage is after the 10-leaf stage.

4. Meteorological conditions. high temperatures in autumn and winter, and dry climate in spring; There are many overwintering hosts, low overwintering mortality and large insect population. It is conducive to the occurrence of coarser disease.

3. Prevention and control methods:

At present, there are no varieties with high resistance or immune coarse shrinkage in production, and the principle of "prevention first, appropriate and early treatment" should be emphasized in the prevention and control.

1. Improve the growth environment of corn. Pomineous weeds are the source of corn rough shrinkage disease, and weeds in the field and ground should be eradicated in time to destroy the suitable habitat of gray planthopper.

2. Pre-sowing agent seed dressing. Before sowing, the effective gram of imidacloprid per mu and the kilogram of corn seeds mixed can effectively control the planthopper; Or add 100 ml of 50% phosphine emulsifiable concentrate to kilograms of water, mix 50 kilograms of corn seeds, pile up for 4-6 hours, dry and sow seeds.

3. Post-seedling prevention. After corn emerges, 10% imidacloprid wettable powder or 3% acetamiprid emulsifiable concentrate 1000 times liquid spray control is used.

4. Spraying prevention and control in diseased fields. In the early stage of corn rough shrinkage disease, spray 20% virus A 500 times or 1000 times of plant disease emulsion in time, spray once every 7 days, and spray 2 times in a row; An appropriate amount of potassium dihydrogen phosphate can be added at the same time as spraying.

5. Strengthen water and fertilizer management and improve maize disease resistance.

Maize dwarf mosaic disease can be infected throughout the growth period, and the disease is most prevalent from seedling stage to 7-leaf stage. The diseased leaves of the damaged corn faded and lost their green color and were mottled with flowers and leaves, and the seedlings infected in the early stage had rotten rhizomes and died prematurely. The comprehensive measures to prevent and treat the disease mainly include the following:

1.Choose disease-resistant varieties.

Select seeds and disease-resistant varieties from disease-free areas to cultivate strong seedlings.

2.Adjust the corn sowing date.

Early sowing of plastic film is advocated for spring maize, and the sowing is completed before the end of April. Avoid the peak of aphids and the growth period of maize susceptible to disease.

3.Improve disease resistance.

Increasing the application of organic fertilizer, adjusting the amount of nitrogen, phosphorus and potassium fertilizer, increasing the application of zinc, iron and other micro-fertilizers, and doing a good job in formula fertilization can effectively reduce the occurrence of the disease.

4.Remove the source of primary impregnation.

Timely removal of weeds in the ground, field edge and field, especially perennial weeds, in order to reduce the base number of aphid insects, timely eradication of stubble and flat field, destroy the living environment of aphids, and reduce the source of primary infiltration. At the seedling stage, combined with the seedlings, the diseased plants should be uprooted in time, and other crops should be replanted in time for the fields that have been seriously ill to reduce economic losses.

5.Control pests and diseases.

Imidacloprid is used to control aphids on weeds in the field, at the head and edge of the ground at the seedling stage, and at the same time, the mixed spraying of antibiotics such as virus Qing and Chinese fertilizer at the seedling stage can effectively prevent the occurrence of diseases.

Corn dwarf mosaic disease, also known as jade potato sunflower leaf streak disease, yellow-green streak disease, is a disease caused by corn dwarf mosaic virus. Dwarf mosaic disease of maize can occur in the whole growth period of maize, and the disease is serious at the seedling stage. At the beginning of the plant, there are many oval, green dots or markings between the veins at the base of the heart leaf, which are arranged along the veins, and then the leaves turn yellow, and some even dry up directly.

The number of ears of maize, especially the number of ears of commercial sweet corn, will be significantly reduced due to MDMV infection, and the fresh weight of ears will be reduced by more than 30%.

When the spike length is reduced, the diameter is also affected. Diseased ears tend to be not full, and the number of rows and grains per panicle decreases. The 1000-grain weight of diseased maize became smaller, especially the basal grain, and decreased by 26%.

MDMV infection significantly affected the total maize yield, with a 42% decrease per plant for common maize and a 75% drop in maize inbred lines or sweet maize, especially for late sowing. The germination rate of maize seeds on diseased plants decreased by 20%, and the length and width of primary roots produced by seed germination decreased by 20% and respectively.

Maize can be infected during the whole growth period, and the damage at the seedling stage is serious. It is the susceptibility stage before tasseling. At first, there are many oval-shaped green spots or markings between the veins at the base of the heart leaf, arranged in intermittent strips along the veins.

The disease progresses further and broad green streaks are formed on the leaves, especially on the new leaves. Chlorophyll decreases, leaves turn yellow, and tissues become hard, brittle, and easy to break, and some start from the tip and edge of the leaf, showing purple stripes, and finally dry up.

Generally, the green band of the first diseased leaf develops into an inverted "eight" shape along the leaf base, and the upper diseased leaf becomes a mosaic when all the leaves are left. Dwarf maize mosaic disease is one of the major maize diseases in the world and China. It is widely distributed in China and occurs in important corn-growing regions.

However, only in most areas of North China, Southwest China, and Northwest China, the damage is serious, and the general loss is 3-10%. The prevention and control methods of corn dwarf mosaic disease mainly include crop rotation, selection of disease-resistant varieties, deep drying, flat cropping, strengthening cultivation management, agricultural prevention and control, and timely uprooting of diseased plants in the field.

Faded green spots. As the plant grows, it appears as a typical mosaic leaf. The leaves of some varieties show yellowing of interveined mesophyll, and the leaves are striped and passerine-like.

The selection of hail-resistant varieties is the most economical and effective preventive measure;

When planting spring corn, it is best to use plastic film mulching, which can not only make corn emerge early, avoid the peak period of aphid migration and poisoning, but also have the effect of repelling aphids, so that the diseased plants in the field are reduced by about 60% compared with conventional open field cultivation. In addition, the warming and moisture retention effect of plastic film will also advance the growth period of maize, delay the growth of diseased plant rate, and reduce the diseased plant rate by more than 80% compared with that cultivated in open field.

Cultivation measures such as foot fertilizer, reasonable top dressing, timely watering, and weeding can promote the healthy growth of maize, enhance the disease resistance of plants, and reduce the occurrence of diseases.

The whole growth process of the potato is relatively slow, the leaves are yellow, and the rhizome is relatively thin, which are the characteristics of corn dwarf flowers, and some spots appear on the roots and leaves of corn; During the early sowing period, it is necessary to avoid the peak period of pests, strengthen management, clean up weeds in time, improve fertility, strengthen fertilizer and water management, and improve the resistance of corn to improve the resistance of corn in the variety should also choose some virus-resistant high products, strengthen protection during the usual planting period, and choose some, the soil is more fertile, and the area is planted for planting.

The disease of corn leaf flowers will grow many irregular spots in the early stage. In the later stages, as the chlorophyll decreases, the leaves will turn yellow and can easily be broken off at the top of the head. The comprehensive management between corn can be strengthened, and the corn seedlings with symptoms can be pulled out in time, and the rapid growth can also choose to use carefully cultivated excellent seeds Changyan to plant.

Faded green spots. As the plant grows, it takes on a typical mosaic shape. The leaves of some varieties showed inter-vein mesophyll changes, and the leaves were striped. When planting spring corn, the mulch film is covered with rotten qi, which not only makes the corn hungry early, but also covers.

Corn dwarf mosaic disease is also known as corn mosaic streak disease. The overall appearance of the diseased maize plants is yellow, weak, dwarf, and slow growth, which can cause a significant reduction in maize yield when it occurs severely. In terms of prevention and control, it is necessary to actively adopt comprehensive agricultural and chemical control measures.

Domestic corn dwarf mosaic disease is mainly caused by sugarcane mosaic virus infection, which forms yellow-green spots on the heart leaves in the early stage of the disease, and gradually expands into stripes over time until the corn dies.

When the climate is not conducive to the pathogen, it shows faded green stripes, so it is called mosaic stripes. The bracts, leaf sheaths, and male flowers of seriously diseased plants sometimes appear greenish spots, and the plants are dwarf, unable to tassel, late tasseling, or do not set fruit. On sorghum, there are symptoms such as mosaic leaves, red leaves, red stripe spots, dwarfing, dry heart, and local necrosis (color version 5).

After the corn seedlings are unearthed, the virus is transmitted to the corn seedlings through the gray planthopper. Maize is susceptible to disease before the 5-leaf stage, and the disease resistance is enhanced after the 10-leaf stage, and the disease is relatively mild even if it is infected. The maize seedling to the 5-leaf stage met with the peak of the gray planthopper migration, and the disease was serious, so the maize sowing stage had a great impact on the maize disease.

Prevention and control of this disease, do a good job of spraying to prevent and control the disease, in the plant closure period, at the latest when the disease is found when the spray, spray 300% copper oxychloride suspension 600 times, or 77% can kill 800 times the suspension agent. 20% quinacethone wettable powder 1000 times sprayed 2 to 3 times, once every 7 to 15 days, alternately sprayed, the effect is better.

If the autumn and winter of the previous year, the weather is dry, the climate is warm and there is little rain and snow, in the spring of the following year, the temperature rises too early, if the corn is sown too early at this time, then it is conducive to the overwintering and reproduction of pests such as gray planthoppers, and the occurrence of corn stripe disease will cause great hidden dangers, in such an environment, it is particularly conducive to the occurrence and development of the disease. Brown to dark brown stripes or leaf spots are born on corn leaves and leaf sheaths, and in severe cases, the lesions are fused. Some lesions are long strips, causing the leaves to be dark brown and dry.

When the humidity is high, a lot of pus overflows from the diseased area, which becomes a brown skin after drying, and is easy to fall off after being washed by rain.

Prevention and control measures: strengthen fertilizer and water management to improve disease resistance;

For the treatment of aphids and disease prevention, 1000 times of dimethoate emulsion can be used, or 1200 1500 times of dimethoate oxide can be sprayed in the peak migration period of wheat aphid.

Once or twice, it can kill aphid mediators and reduce the harm. If combined with the control of aphids in wheat fields, the effect is better.

For the prevention and control of pests and diseases, insect control and disease prevention, you can choose to use 20% Zhengye imidacloprid 3000-4000 times liquid + new high-lipid membrane to prevent and control poison-spreading pests. For the prevention and control of diseases, it is introduced that virus gram 1000 times liquid + plant cell satisfaction factor spray can be used to improve plant stress resistance, which can make viral DNA fragmentation and apoptosis. Strong immune function, induce interferon and active interleon, inhibit the replication of residual viruses, and promote the ecological growth of plant positive energy.