Edamame disease downy mildew is very common, what are the symptoms of downy mildew in edamame?

Generally damage the leaves, the disease jump is generally on the upper leaves, the initial outline of the lesions is not obvious, light yellow, and then turn black, the back of the leaf is densely covered with a light purple mold layer, when the humidity is high, the more serious the disease. In case of continuous rainy weather, 45 chlorothalonil smoke removal agent 250 grams of smoke control can be used per mu, divided into 5 6 piles in the greenhouse in the evening, smoked overnight after being lit with a dark fire, ventilated the next morning, once every 8 10 days, there are many reasons for the disease of edamame, which may be the poor disease resistance of the variety, unreasonable fertilization, the soil is not suitable for planting edamame, environmental factors, weak plants, very dark light, etc.

There are four common pests and diseases in edamame, one is downy mildew, the second is gray mold, the third is gray spot, and the fourth is sclerotinia sclerotinia. Soybean mosaic disease is mainly caused by soybean mosaic virus, peanut streak virus, soybean dwarf virus, tobacco necrosis virus, alfalfa mosaic virus and other viral infections, sometimes alone, sometimes mixed infection.

Downy mildew, in which the fungus overwinters on diseased carcasses or seeds with oospores. In the second year, when conditions are ripe, oospores germinate to produce sporangia, which release zoospores, which are spread by rainwater sputtering, invade from the embryo, and infect the system. In the process of growing edamame, many chemical fertilizers and watering are under the control of farmers, such as powdery mildew, which generally occurs at the pod-setting stage, and there will be a white powdery object in the early stage, and then the powdery object will become a spot.

In the growth process of edamame, the implementation of many chemical fertilizers and the amount of watering are to be controlled by farmers, like powdery mildew generally occurs in the pod-setting stage, there will be white powdery objects in the initial stage, and then the powdery objects become spots, generally harming the leaves, the lesions generally appear on the upper leaves, the initial outline of the lesions is not obvious, light yellow, and then become black, and the back of the leaves is densely covered with a light purple mold layer, and the higher the humidity, the more serious the disease.

The leaves will turn yellow, and there will be various small yellow spots on the leaves, gray mold will appear, and there will also be symptoms of wilting.

After edamame and downy mildew, the entire leaf and leaf cake will turn white. And if the fruit has already been produced, the inside of the fruit will also rot. Severely affects yields.

The leaves will turn from green to yellow, and insects will gradually grow on the leaves, which will slowly cover the entire leaf until the entire plant is dead.

Common diseases during edamame cultivation are downy mildew, powdery mildew, aphids, rust, this lesion, etc., which are often seen.

Downy mildew, aphids, powdery mildew, red spiders, rust, anthracnose, these are serious pests and diseases.

Pod blight, downy mildew, rust, powdery mildew, anthracnose, these diseases are also relatively serious, we must pay attention to.

Powdery mildew, downy mildew, anthracnose, rust, and disease spots all appear when edamame is grown, and there are many distinct characteristics.

The first point is that there will be a lot of black dots on the edamame, which is very scary, so you should pay attention, the second point is that you will find that there will be a lot of bugs on the edamame, and there must be a virus at this time, and the third point is that the edamame does not grow very well, and there is also the phenomenon of yellow leaves, which should be paid attention to at this time.

Edamame downy mildew is characterized by small yellow spots on the leaves and sporangia on the dorsal backs of the leaves.

The disease is mainly manifested on edamame leaves, and there will be a lot of mold on the infected leaves.

Answer]: The causative agent of soybean downy mildew is downy mildew in Northeast China, which belongs to the phylum Oomycetes. Downy mildew is common in soybean producing areas, and it occurs more often in cold areas.

It mainly harms seedlings or adult leaves, pods and beans. The seedlings grown from diseased seeds can be systematically diseased, and there are no symptoms in the cotyledons, and there are greenish patches from the base of the first pair of true leaves, which expand along the main vein and lateral veins, causing the whole leaf to turn green. Later, the leaves of the whole plant can be visible.

Before and after the flowering period, there is a lot of rain or high humidity, and the back of the lesion is imitating a gray mold layer, and the diseased leaves turn yellow and brown and dry up. The external symptoms of pod infection are not obvious, but the yellow mold layer often appears in the pod, that is, the mycelium and oospores of the fungus, and the affected bean grains are white and dull, and a layer of yellow-white powdery mold layer is attached to the surface.

The sporangia germinate to form a bud tube, which invades from the host stomata or between cells, and spreads between cells to absorb host nutrients by the sucker. The oospores attached to the seeds are the main source of primary infection, and the oospores can germinate with the germination of soybean, form sporangia and zoospores, invade the host hypocotyl, enter the growth point, and spread to the whole plant to become the diseased seedlings of systemic infection. The diseased seedlings have become the source of re-infection.

Prevention and control methods. Breeding of disease-resistant varieties: According to the dominant varieties of local pathogens, select and promote disease-resistant varieties, such as Zaofeng No. 5 and Baihua File in Jilin.

Seed treatment: Seed dressing with Chlormyces reviscosa, or Grammycolin, Formecis and Dixon. Removal of diseased seedlings:

The symptoms of diseased seedlings are obvious and easy to identify, and the diseased seedlings can be pulled out by combining cultivating and weeding to reduce the source of infection. Spraying agents: When the epidemic conditions of the disease appear, spray and control with enoylmorpholine, aluminum ethidronate, carbendazim, antibacterial special and so on as soon as possible.

Symptoms: After the leaf is damaged, the leaf surface produces yellowing dots at the beginning, gradually turns gray-brown, when wet, the back of the leaf produces gray mold, and when it is serious, the leaf withers and falls off, and the whole plant dies. After the pod is damaged, a gray-white mold layer is formed on the surface of the seeds inside the pod, and the symptoms outside the pod are not obvious.

1. Select disease-resistant varieties and implement crop rotation for more than 2 years. 2. Reasonable dense planting, timely removal of diseased residues, deep soil turning, and reduction of pathogen sources. 3. Before sowing, soybean seeds should be mixed with 50 fumei double wettable powder with seed weight, or with 70 dixone, 80 acetphosphine aluminum or 35 rhizopus mildew with seed weight.

4. Spray pesticides for prevention and control in the early stage of the disease.

The onset is yellow-brown spots on the leaves. It mainly damages seedlings or adult leaves, pods and bean grains. Seedlings grown from diseased seeds can cause systemic disease, showing greenish patches from the base of the first pair of true leaves, expanding along the main and lateral veins, causing the whole leaf to turn green.

Fertilizer and water management and pest control can be strengthened.

It is mainly manifested on the leaves and branches, the leaves will turn yellow, and the branches and leaves will wither; It can be prevented with drugs, sprayed with 80% antibiotics, seeds should be treated before sowing, soaked in salt water before sowing.

When soybean downy mildew damages the leaves (from the seedlings can be harmed), there will be some small patches, in the case of seedlings, the color is relatively light (similar to greening), which will expand with the main vein and side veins, and in severe cases, the whole leaf will fade green.

If you are infected with downy mildew at the adult stage, at the beginning, there will be small spots that fade green, and then turn into small patches, from the outside, similar to the macula, and in the later stage, the color changes from yellowish brown, and the back of the leaf can be turned over, and a mold layer can be found to appear, and the color is gray.

1. Crop rotation planting.

Crop rotation is a good way to prevent downy mildew, especially a field planted with soybeans all year round, the occurrence of downy mildew will become more and more serious, and after 3 years of rotation planting with other crops, the downy mildew situation will be greatly improved.

2. Disease-resistant seeds.

Buying seeds with strong disease resistance can also effectively prevent the occurrence of downy mildew, and under the same conditions, seeds with strong disease resistance have its unique advantages.

3. Field management.

The field management mentioned here includes many aspects, such as reasonable dense planting, not too dense planting; Flood irrigation is prohibited to prevent excessive humidity in the field; Fertilizer should be plentiful but not excessive; Pay attention to the prevention of weeds in the field, etc., that is, our normal field management should be in place.

Answer: Hello, soybean downy mildew is a disease caused by downy mildew in Northeast China and occurs on soybeans. It can be diseased during the growth period of soybean, and it is harmful to soybean seedlings, leaves, pods and grains. The most obvious symptom of the disease is downy mildew on the dorsal surface of the leaves.

Ask what to do if there is mycosis on the bean leaves and there are bean worms.

Ask if there will be any problems with the insects raised.

No questions will be asked. Is there any other way?

3. All soybean downy mildew occurs in all soybean producing areas across the country. It is common in Northeast China and North China, and Heilongjiang and Jilin are the most serious. Due to downy mildew, the diseased leaves fall early, and the yield and quality of soybean are reduced. Due to the decrease in oil content of sown diseases, the emergence rate also decreased.

Symptoms: Leaf lesions are yellowish-green, round or irregularly shaped. Under wet conditions, grayish-white mold (i.e., sporangia and sporangia) grows on the back of diseased leaves. There is a gray mold layer inside the affected pods. There is a lumpy grayish-white mold layer on the surface of the diseased particles.

The causative agent Paronospora Manshurica (Naun.)）syd., a fungus of the order Downy Mildew of the subphylum Algae.

The sporangia peduncle is solitary or several clusters protruding from the stomata, colorless, dendritic. The main branches are symmetrical, slightly larger at the base, and the apex is divided into 3 or 4 times 2 branches, curved or slightly bent. The twigs are right-angled or acutely angled, and the tip of the last twig is sharp, and one sporangia grows on it.

The sporangia are oval or obovate, a few spherical, colorless or slightly yellowish, unicellular, mostly without milky protrusions. The oospores are spherical and yellowish-brown.

Pathogenesis. Downy mildew is an oosporous overwintering in seeds, diseased pods and diseased leaves. The following year, it became the first impregnation source. After overwintering, oospores produce zoospores to infect the germ, enter the growth point, and then spread to the true leaf and axillary bud to form a systemic infection.

Later, a large number of sporangia grow on the diseased seedlings and diseased leaves, which spread with wind and rain and then invade the host, spread among the host cells, and then form sporangia and sporangia, so as to carry out multiple infections. After pod-setting, the pathogen invades the pod with hyphae, and oospores stick to the seeds. The rate of seed carrying and the source of bacteria in the field are related to whether the disease can occur.

Where the seed carrying rate is high and the soybean continuous cropping field has many bacterial sources, the disease will occur severely. The occurrence and epidemic of downy mildew are related to the temperature, humidity and rainfall at the time of the onset. The formation of sporangia requires dew on the foliar surface, and the foliar dew condensation time is more than 10 hours, and the sporangia can be formed in large quantities.

As a result, the disease occurs heavily in years with high rainfall and high humidity. The appropriate temperature for sporangia formation is 10 25, and the temperature required for spore formation is low, but the temperature for mycelial growth is higher than that for spore formation. The average temperature in Northeast China and North China in July and August is 20 24, and the temperature difference between day and night is large, which is the rainy season, which is conducive to the epidemic of diseases.

Where there is little rainfall in July and August, the incidence is mild in dry years. There were significant differences in disease resistance among cultivars. Therefore, the large-scale planting of susceptible varieties will create conditions for the epidemic of diseases.

Prevention and control methods. 1) Planting disease-resistant varieties. Jiunong No. 9, Pastor No. 1, Dongnong No. 36, Hefeng No. 25, Henong No. 21, Jilin No. 21, etc.

2) Agricultural control. Crop rotation for more than 2 years in severely diseased areas; After soybean harvest, deep ploughing was carried out to remove the remains of diseased leaves in the field and reduce the source of bacteria. increase the application of phosphorus and potassium fertilizers; Increase the number of tillage, promote the growth of plants, and improve disease resistance.

3) Pharmaceutical prevention and control. Before sowing, the pesticide seed dressing can be carried out, and 35% methyl frost (Rhizopus triacetylphosphate % aluminum triacetate (ethylphosphine aluminum % dixone, etc.), the dosage is the weight of the seeds, and 50% carbendazim and 50% Fumei can be mixed according to the ratio of 3 2, and the amount of seed weight can be dressed.

There is mycosis on the bean leaves, and there are bean insects on the bean leaves.