What causes corn spot? How to treat it?

Symptoms, causes and prevention methods of corn large spot disease.

Corn large spot disease, also known as coal streak disease, is one of the important diseases of corn, corn large spot disease is mainly to damage leaves, and in severe cases, it is also harmful to leaf sheaths and bracts. Generally, it starts at the bottom of the leaf and gradually expands upward, but it often starts from the middle and upper leaves. The main symptom is dark brown on the edge of the lesion, ** light brown or black-gray larger lesion, and severe lesions fuse together, causing the whole leaf to die.

Control measures: 1. Choose varieties resistant to large spot disease. When purchasing seeds, attention should be paid to selecting excellent varieties with strong disease resistance, high germination rate, high yield and convergence.

In particular, the dosage of pesticides and insect pests is different for each crop. Different pesticides and herbicides will be poured into the occurrence of corn leaf disease. Corn leaf spot basically occurs in the late growth stage of maize.

As long as the early prevention work is done well. In the later stage of corn, the water moisture is uniform, and the large spot disease of corn leaves will not occur, and the disease is the most serious before and after heading. The appropriate temperature for the onset of the disease is 26 32, but the key condition for the onset of the disease is that there is more rainfall and more rainy days in summer.

In the case of low terrain, high plant density, partial application of nitrogen fertilizer, delicate growth, early sowing, etc., the disease is severe, and the application of organic fertilizer, phosphate fertilizer, potassium fertilizer, and intercropping is implemented, and the disease is mild.

Through wide and narrow row planting, the ventilation and light transmission between plants can be increased, the field humidity can be reduced, and the conditions unfavorable for the infection and morbidity of pathogens can be created. The intercropping of maize with dwarf crops can also effectively regulate the field microclimate, create better growth conditions for plants, and reduce the occurrence of diseases. Agricultural control measures:

Plantar fertilizer was applied, phosphorus and potassium fertilizer were applied to improve plant disease resistance; Intercropping with other crops to improve the ventilation conditions of corn fields and reduce the infiltration of pathogenic bacteria.

The plot with poor soil is heavier than the fertile plot, the planting density is too dense than the normal plant spacing, the plot with poor ventilation is heavier than the well-ventilated plot, and the continuous cropping is heavier than the rotation plot.

50% carbendazim wettable powder can be used to spray corn plants with water at a ratio of 1:500, and corn large spot disease can be cured by spraying for three cycles in a row; Or spray corn plants with 75% bacterium wettable powder at a ratio of 1:400 with water, and spray 3-4 times in a row.

Enhance the disease resistance of corn, and it is necessary to inject some pesticides in advance, and at the same time, it is also necessary to carry out high-temperature fermentation treatment to avoid the peak period of insect infestation.

Intensify cultivation, select excellent varieties, and use professional pesticides to eliminate this pest and disease.

Corn should be protected by pesticides to prevent spot disease during the flowering period, so as not to cause an uncontrollable situation in the later stage.

Pesticides to prevent pests and diseases should be sprayed, and phosphorus and potassium fertilizers should also be used, so that weeding can be done well, and it is also excellent.

Corn leaf spot is a common leaf disease in corn-producing regions around the world. The disease in the summer maize area in China is more serious than that in the spring maize area, which can cause huge losses in the epidemic years.

1) Symptomatic maize will cause great losses from seedling stage to adult stage, especially at the tasseling stage and grain filling stage. The lesions are mainly concentrated on the leaves, generally starting from the lower leaves and gradually spreading upwards. At first the spots have water stains, then they turn yellowish-brown or reddish-brown with darker edges.

The lesion is oval, nearly round or oblong, and the size is 10 15 mm 3 4 mm. Sometimes, 2 or 3 concentric helices are visible within the lesion. (2) Infection route and pathogenesis.

The pathogenic bacteria overwinter in the form of hyphae or conidia in the body of diseased remnants, and produce a large number of conidia in the following month when the temperature is relatively suitable, and spread them through air currents or rainwater. After the spring maize is harvested, the conidia left on the diseased residues in the field can continue to spread to the summer maize field. Therefore, in areas where spring maize and summer maize are mixed, the incidence of summer maize is always more severe than that of spring maize.

From July to August, temperatures above 25 in North China are the most suitable for the epidemic of the disease. There are many rainy days, heavy rainfall, and high humidity, and small spot disease will occur severely. (3) select disease-resistant varieties as control methods; strengthen cultivation management, promote robust growth, and improve plant disease resistance; clean the countryside, concentrate on incinerating the sick and disabled, and reduce the source of disease; At the initial stage of the disease, spray 500 times of 50% carbendazim wettable powder, 500 times of 65% mancozeb wettable powder, 500 times of 70% thiophanate-methyl wettable powder, 800 times of 75% chlorothalonil wettable powder or 100-120 times of aqueous solution of agricultural resistance 120, and spray once every 7 days continuously from the end of the heart lobe to the tasseling stage.

Control methods: The prevention and control of corn large spot disease should be mainly based on planting disease-resistant varieties.

Strengthen cultivation management, supplemented by necessary pesticides for prevention and control. The prevention and control measures of cultivation management measures mainly include: timely removal of diseased plant residues in the field after corn harvest; Wheat ridge planting, early sowing at the appropriate time to avoid diseases; In the early stage of the disease, timely removal of 1 3 diseased leaves at the base of the corn stem can reduce and delay the disease damage. After the corn is harvested, it should be ploughed in time, the straw should be treated centrally, and the fertilizer used as a compost fertilizer should be fermented at high temperature; Crop rotation for more than 1 year, etc.

<> corn large spot disease mainly harms the leaves of corn, and the diseased leaves will show fusiform lesions. The lesion is preceded by water-stained bluish-gray spots that then expand along the veins to the ends to form large spots with dark brown edges, light brown or bluish-gray edges. In the early stage of the disease, drugs such as 500-800 times of 70% methyl tobuzin wettable powder and 500 times of carbendazim wettable powder can be used for spray prevention and control.

1. Symptoms and prevention methods of corn large spot disease

1. Corn large spot disease mainly harms the leaves of corn. Generally, the disease starts from the bottom of the leaves, and most of the lesions on the affected leaves are fusiform. The lesions appear before they appear with water-stained bluish-gray spots, which then expand along the veins to the ends to form large spots with dark brown edges, light brown or bluish-gray at the edges.

The lesions are about 5-10 cm long and about 10-15 cm wide, and a black mold layer will be produced on the lesions on the back of the leaves in the later stage.

2. In the early stage of corn disease, 500-800 times of 70% methyl tobuzin wettable powder, 500 times of 50% carbendazim wettable powder, 600 times of 50% thiophanate-methyl wettable powder, and 500-800 times of 50% antibacterial special wettable powder can be sprayed for spray control, sprayed once every 10 days, and continuously prevented 2-3 times.

3. For plots with more serious diseases, crop rotation can be implemented and reasonable dense planting can be carried out. In ordinary times, we must pay attention to the management of water and fertilizer, increase the application of phosphorus and potassium fertilizers, and do a good job in cultivating and weeding. During the corn growth period, the bottom 2-3 leaves can be removed to prevent the formation of pathogens.

2. How is corn large spot disease caused?

1. Corn large spot disease is mainly caused by Helminospora magatum. The shape of Helminospora machiola is pale blue-brown, fusiform or long fusiform, straight or slightly curved, slightly pointed at both ends, and consists of 4-7 septums.

2. The hyphae and conidia of corn large spot disease can be overwintered in vitro and in vivo. Sometimes, the seeds can also carry a small amount of pathogens, which can become the source of infection in the second year, and the pathogens will invade the corn plant under suitable temperature and humidity conditions.

3. The temperature is 20-25 and the relative humidity is above 90%, which is conducive to the development of diseases. Temperatures above 25 or below 15 and relative humidity less than 60% will inhibit the development of diseases. During the period from jointing to heading of corn, we must pay attention to timely prevention and control.

In the process of preventing and controlling corn large spot disease, it is necessary to choose varieties with good disease resistance for planting, and also need to renovate and dry the soil before planting to eliminate the pathogens in the soil.

1. Description of symptoms

After the occurrence of large spot disease in corn, blue-gray spots will appear on the bottom leaves, and over time, the spots will continue to expand, and then infect the whole plant, causing the corn to rot and die. At the same time, when wet, you will find a large amount of black mold distributed above the spots.

2. Disease-resistant varieties

In the prevention and control of corn large spot disease, it is necessary to select varieties with strong disease resistance for planting. Before planting, the seeds can also be soaked in warm water to eliminate the germs on the seeds, or the seeds can be soaked in potassium permanganate or carbendazim solution to improve their disease and insect resistance.

3. Soil preparation and fertilization

Most of the pathogens of large spot disease will breed from the soil and infect corn plants, so the soil needs to be treated in the process of control. Before planting, the soil can be turned deep and exposed to the sun to dry to destroy bacteria in the soil, or quicklime can be mixed into the soil to help the corn grow better.

4. Regular inspections

In the process of daily management, it is necessary to regularly inspect the corn plants, once it is found that there are spots on the bottom leaves, it needs to be destroyed in time to avoid infecting other healthy plants, and at the same time, when watering the corn, only need to keep the soil slightly wet, and not make the soil waterlogged.

Corn leaf blight is a common disease of corn cultivation in Northeast China. It has the characteristics of wide distribution, rapid development, heavy harm, difficult control and filial piety. Every year, the yield of corn will drop significantly, and even 50-60% or even no harvest.

So how to effectively prevent and control? Let's find out.

Symptoms of corn leaf spot.

Corn leaf spot, also known as leaf blight, stripe spot and leaf blight, mainly affects corn leaves, leaf sheaths and covered leaves. Leaf disease will appear as small water-gray spots, which then quickly spread to the sides along the veins to form large brown spots. In severe cases, the disease will continue, the leaves will turn yellow and wilt, and the seedlings will die, resulting in large radiation, reduced yield or even failure.

Conditions under which corn leaf spot occurs.

The occurrence of corn leaf spot is not only related to the degree of susceptibility of maize varieties, but also closely related to local climatic conditions. The temperature is 20-25 degrees and the relative humidity is greater than 90%. During the period from jointing to heading, the disease progresses rapidly and spreads easily.

The more severe the disease, the lower the nitrogen application rate from booting stage to heading stage, and the higher the density of low-lying land.

Prevention and control measures for corn leaf spot.

1. Screen out resistant varieties. At present, there are many varieties of maize seeds, and the disease resistance varies greatly among varieties.

2. Strengthen agricultural regulation and control. The base fertilizer should be mixed with organic biological fertilizer and boron, magnesium, zinc, silicon sulfate and other medium and trace elements, and the seedling stage 6-8 leaves should be sprayed with light carbon fertilizer to strengthen the plant and prevent diseases.

3. Take medicine for prevention. Selecting the appropriate agent for pre-disease and disease prevention is an effective measure to prevent and control corn leaf blight.

4. Prevent in advance. In mid-June, 250g of corn per plant, 400 500kg of water, and 2 sprays in 10 15 days can effectively control corn leaf blight.

5. The first stage of the disease. In the early stage of the disease, spraying once every 5 7 days, spraying twice in a row, 500 grams of corn fungus per hectare, and watering 500 600 kg can prevent and control corn leaf blight and make corn grow healthily.

The above is an introduction to corn leaf spot, in order to effectively ensure the yield and quality of corn, all kinds of pests and diseases must be strictly controlled, and corn leaf spot is no exception.

Corn small disease, corn large spot disease, also known as stripe spot, leaf spot, leaf blight, coal streak disease, etc. Onset, mainly harms leaf sheaths, leaves, and leaves. The leaves of the affected plants appeared water-stained blue-gray lesions, which expanded to both sides, forming dark brown edges and large blue-gray spots in the middle.

Generally 20-25 degrees, high humidity, high density is easy to susceptible. For prevention and control, carbendazim, thiophanate-methyl, chlorothalonil, mancozeb, etc. can be sprayed alternately in the early stage of the disease, and the interval is re-sprayed once or twice a week. The above suggestions are for reference only, I hope they will be useful to you.

Corn spot disease is a common disease of corn planting in Northeast China, which has the characteristics of wide distribution, rapid development, serious damage and difficult control, which will cause a significant reduction in corn yield every year, and seriously reduce the yield by 50 to 60% or even no harvest.

So how to effectively prevent and control? Let's take a look.

1. Symptoms of corn large spot disease.

Corn large spot disease, also known as leaf class disease, stripe spot disease, leaf blight, mainly harms corn leaves, leaf sheaths and leaves, leaf disease will show water-stained gray spots, and then rapidly expand to both sides along the leaf veins, forming brown spots, severe disease in a piece, leaves turn yellow and die, into a piece of dead seedlings, resulting in a large radiance reduction in yield, or even no harvest.

Second, the conditions for the occurrence of corn large spot disease.

In addition to the degree of susceptibility of maize varieties, the prevalence of maize spots is also closely related to local climatic conditions.

The temperature is 20 25 and the relative humidity is more than 90%, which is conducive to the development of diseases.

During the period from jointing to ear emergence, the temperature is suitable, and there are continuous rainy days, the disease develops rapidly, and it is easy to epidemic.

The more severe the disease of maize, the more severe the disease was due to insufficient nitrogen fertilizer and excessive density of low-lying land at the booting to heading stage.

3. Prevention and control measures for corn large spot disease.

1. Choose disease-resistant varieties of stuffy jujube.

At present, there are many varieties of corn seeds, and the disease resistance of corn varieties varies greatly, so it is necessary to select corn varieties with strong resistance to lay a good foundation for disease prevention.

2. Strengthen agricultural prevention and control.

The bottom base fertilizer should be mixed with organic biological fertilizer and trace elements, such as boron, magnesium, zinc, silicon, etc., and the seedling stage 6 8 leaves should be sprayed with light carbon fertilizer once, so as to strengthen the plant and prevent disease.

3. Pesticide prevention and control.

Not afraid of serious spot disease, afraid of the wrong symptom, selection of the right agent, pre-disease prevention, disease treatment, is an effective measure to prevent and control corn spot disease.

4. Prevent in advance.

Before the onset of the disease in mid-June, 250 grams of corn were grammed, 400 500 kg of water was added, and sprayed again in 10 15 days, spraying twice in a row, which can effectively prevent corn large spot disease.

5. Disease period**.

Timely observation, in the early stage of the disease, add 500 600 kg of water to 500 600 kg of corn fungus, spray once every 5 7 days, spray twice, and have the prevention and control of corn spot disease in Mazhou, so that corn grows robustly.

The above is the introduction of corn large spot disease, in order to effectively ensure the yield and quality of corn, all kinds of pests and diseases should be strictly controlled, corn large spot is no exception, do you have anything to add about corn large spot disease?

That's all for the content of corn spot disease, welcome to read other agricultural content on cucumber network.

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