What causes black spots on watermelon?

Watermelon anthracnose can occur throughout the growth period, but it is the most severe in the middle and late stages of plant growth, resulting in leaf litter and fruit rot. At the onset of the disease, round brown lesions appear on the cotyledons, which develop to the base of the young stem to become black-brown, shrunken, or even folded. At the onset of the adult stage, water-soaked round yellowish spots appear on the leaves, which then turn brown, with purple-brown edges and light brown in the middle, with concentric ring patterns.

After the lesions expand and fuse with each other, it is easy to cause leaf perforation and drying. On the unripe fruit, the initial lesion is water-immersed, light green round spot, the ripe fruit begins to be a protruding lesion, and the later stage expands into a brown depression, and many small black spots are arranged in a ring, and when wet, a pink slime is born, which is mostly deformed or blackened and rotten. It is easy to develop the disease in the case of high temperature and high humidity, it is recommended to pay attention to ventilation at ordinary times, and can be prevented with the agent azoxystrobin or pyraclostrobin or mancozeb or propanzol zinc when the disease occurs, and the best effect after the onset of the disease is prochloraz, prochlorazine manganese salt, difenoconazole, ningnanmycin tebuconazole, bromocyan, pyroxystrobin, benzylmethotrobin, benzopyramidole oxystrobin, benzylmethamide cyanide, etc., prochloraz and azole seedlings are used with caution at the seedling stage, which is easy to inhibit growth, Personally, I recommend cyanide or benzazoxystrobin or tinamycin tebuconazole (pay attention to the dosage).

Watermelon black spot disease mainly damages leaves, but can also infect fruits. Leaf infection, primary water-soaked small spots, distributed between leaf margins or leaf veins, then expanded to round to nearly round dark brown, slightly raised edges, obvious at the junction of disease and health, lesions with little obvious wheel stripes, when the disease is severe, the lesions quickly fuse into large lesions, resulting in leaf wilting, but the diseased stems and vines do not die, different from watermelon vine blight and wilt. The fruit is infected, and the surface of the fruit is initially water-ulcerated dark spots, which then expand into depression spots, causing fruit rot.

When the humidity is high, the disease grows a sparse black mold layer, which is the fruiting body of the pathogen.

Symptoms] mainly damage the leaves, at the beginning of the leaves appear dark green nearly round lesions, slightly water-stained, and later develop into yellow-brown to gray-white amorphous necrotic spots, the edge color is darker, the size of the lesions is different, when the air is humid, the lesions produce gray-brown mold, when the disease is serious, the leaves are densely covered with lesions, and the leaves are necrotic and dry in a short period of time. It belongs to the subphylum Semi-Epiphylum Fungi.

Occurrence rule] High temperature and high humidity are conducive to the onset of the disease. The growing season of watermelon is rainy, the temperature is higher, or the rainy days are more likely to cause more serious diseases.

What causes black spots on watermelon? Anthrax is treated with prochloraz manganese salt, benzobromidonitrile, pythium, anthrax fomei, bromonitrile, pyroxystrobin, pyraclostrobin spray.

Generally speaking, it is black spot or leaf spot. The temperature changes dramatically, with high and low temperatures and humidity.

Hello, watermelon anthracnose, mainly affects leaves, but can also harm stems, petioles and fruits. Round or semicircular brown or black-brown lesions appear on the edge of the seedlings' affected cotyledons, and there are often black-brown halos on the periphery, and small black spots or light red sticky matter are often scattered on the lesions.

Prevention and cure. Implement crop rotation, rational fertilization, reduce the amount of nitrogen fertilizer, and increase the application of potassium fertilizer and organic fertilizer.

The ground is fully covered with mulch film and ventilation should be strengthened to reduce the indoor air humidity to below 70%.

Reasonable dense planting, scientific pruning, to prevent excessive density, in order to reduce the indoor microclimate humidity.

Scientific use of bactericidal pesticides.

There is no picture and no truth.

It is said that the only black thing that can appear in a watermelon is watermelon seeds.

If it's not watermelon seeds, then the watermelon is broken and can only be thrown away.

Watermelon has black spots mainly caused by anthracnose, continuous rainy weather or poor drainage of the planting site, in order to prevent disease, you can first put the watermelon seeds into the carbendazim solution after mixing with water for 1 hour, remove and wash before sowing, in the later stage of watermelon breeding, pay attention to thin fertilizer and apply more, the temperature can be kept at 18-32 degrees.

Watermelon has black spots mainly caused by anthracnose, mainly harmful to leaves, fruits, continuous rainy weather will cause anthracnose, if the watermelon planting site is not well ventilated, poor drainage, too much nitrogen fertilizer, will also cause anthracnose.

Disinfection of watermelon seeds can effectively prevent anthracnose, first soak the seeds in warm water at 55 degrees for 10 minutes, then put the seeds into the carbendazim solution mixed with water, soak for 1 hour, rinse with water after fishing, and promote germination and sowing.

Watermelon in the early growth stage is mainly to absorb the base fertilizer in the soil, but in its flowering and fruiting period, it is necessary to apply a thin organic fertilizer every 15-30 days to ensure that the thin fertilizer is applied more, in order to make the watermelon grow more vigorous, water the watermelon every 10 days, and stop one week before harvest.

Watermelon likes temperature, the most suitable growth temperature is 18-32 degrees, low temperature will affect its normal growth, and watermelon seeds must be above 15 degrees in the environment to germinate, in addition, the temperature difference between day and night is best kept at about 10 degrees, which is conducive to the accumulation of sugar in watermelon.

It's broken.

Generally, the inside of a good watermelon is very good, the bright red color is very attractive, once it is broken, you will find that the inside color of the watermelon will become a little dark red, some black, which means that the watermelon has been put for a long time and is broken.

Often when we eat watermelon, we may not finish the orange, we will put the watermelon in the refrigerator, in order to facilitate the next time to continue to eat, but here we have to pay attention to one point, that is, when the watermelon is put in the refrigerator, we had better not wrap it with plastic wrap, do not think that the watermelon is not easy to change after using plastic wrap, on the contrary, the plastic wrap on the ear potato actually increases the growth of bacteria.

Trick to tell if the watermelon is broken.

Whether the watermelon is broken or not is actually very easy to distinguish, first of all, the skin of the broken watermelon will become very soft, when you pinch it with a little hard with your hand, you will find that the skin of the good watermelon you can't pinch, the whole contains juice, but the bad watermelon you will find that its skin is very thin and very soft, and there is very little juice in it, just like dehydration.

Secondly, once the watermelon is bad, you will find that when you eat it, you will feel that the taste of the bad watermelon is a sour feeling, the good watermelon is generally sweet and occasionally has a little sourness, but it will not feel anything, and the bad watermelon is different, the bad watermelon you will feel that its taste is not only sour and its juice is very small, very dry and dehydrated.

Watermelon pubic skin disease.

1. Symptoms. At the beginning of the disease, small water-soaked spots appeared on the surface of watermelon fruits, which were not easy to find, and then rapidly developed and expanded, forming irregular water-soaked large lesions. The lesions mostly occur on the upper surface of the fruit, and the later stage is a small crack.

The lesions are obvious on the surface of the fruit, and the flesh of the fruit decays with the development of the disease.

2. Pathogen bacteria.

The scientific name of the pathogen is still controversial, and according to the research of relevant domestic units, it is considered to be a Gram-positive bacillus.

3. Onset conditions.

The pathogen is easy to remain in the soil or the residue of diseased plants, and the disease can occur after watermelon is set on the melon to the fruit ripening stage. The high temperature and high humidity from July to August are conducive to the infection and onset of pathogens. The amount of fertilizer applied in the farm is small, and the proportion of nitrogen, phosphorus, potassium and calcium fertilizer is unbalanced.

Nitrogen overabundance and plant malnutrition can lead to the reduction of plant stress resistance and disease resistance. Heavy stubble is severe. Varieties with pale green peel are the most susceptible, varieties with dark green stripes are disease tolerant, and varieties with dark green or dark green peels are the most tolerant.

Fourth, prevention and control methods.

1. Agricultural prevention and control.

1) Clean up the remains of diseased plants in the field. After harvesting, the diseased residues are burned before land preparation or in the field to reduce the source of infection at the beginning of the following year. Or pull out the central diseased plant immediately after it is found in the field, and burn it or bury it deep away from the melon field.

2) Crop rotation. It is best to implement crop rotation for more than 3-5 years on the plot where watermelon is planted to reduce the chance of parasitism, reproduction and infection of pathogens and reduce the bacterial content in the soil.

3) Choose disease-resistant or disease-resistant varieties. Choose varieties with dark green skin, dark green stripes on melon skin, dark green and black skin, because these varieties have better disease resistance or disease resistance.

4) Reasonable fertilization. Reduce the amount of nitrogen fertilizer, and appropriately increase the amount of phosphorus, potassium and calcium fertilizer to improve and balance the nutrient status, achieve nutrient balance, and improve the stress and disease resistance of plants.

2. Strengthen the plant quarantine of imported varieties and cut off the artificial transmission of pathogens.

It's broken.

Generally, a good watermelon has a good bright red color inside, which is very attractive, once it is broken, you will find that the inside color of the watermelon will become a little dark red, and some are black, which means that the watermelon has been put for a long time and is broken.

Often when we eat watermelon, we may not be able to finish, so we will put the watermelon in the refrigerator to facilitate the next time to continue eating, but we should pay attention to one point in the ear potato, that is, when we put the watermelon in the refrigerator, we had better not use plastic wrap.

Wrap him in a bag and don't think that the watermelon is not easy to change after using plastic wrap, on the contrary, adding plastic wrap actually increases the growth of bacteria.

Trick to tell if the watermelon is broken.

Whether the watermelon is broken or not is actually very easy to identify, first of all, the skin of the broken watermelon will become very soft, when you pinch it with your hand a little harder, you will find that the skin of the good watermelon you can't pinch, the whole contains juice, but the bad watermelon you leak orange will find that its skin is very thin and very soft, and there is very little juice in it, just like dehydration.

Secondly, once the watermelon is bad, you will find that when you eat it, you will feel that the taste of the bad watermelon is a sour feeling, the good watermelon is generally sweet and occasionally has a little sourness, but it will not feel anything, and the bad watermelon is different, the bad watermelon you will feel that its taste is not only sour and its juice is very small, very dry and dehydrated.

The blackening of watermelon leaves is common and may be caused by black spot disease.

Watermelon has brown spot disease leaf loss of green and loss of photosynthesis, which is caused by brown spot disease or anthracnose, and the main reason for the blackening of watermelon leaves is black spot disease. In the early stage of the disease, chlorothalonil, chlorothalontoin or mancozeb can be prevented and controlled, and various agents are used alternately.

In fact, black spots on the leaves of watermelon are symptoms of a variety of diseases, among which the more common is anthrax, anthrax is likely to appear in the whole period of watermelon, black spots are its initial symptoms, with the growth of watermelon, the black spots will slowly become larger, and will affect the quality of the fruit. Raised patches will also appear on the fruit of watermelon, which seriously affects the yield and quality of watermelon and causes great economic losses to melon farmers.