What causes small brown spots on the leaves of planted tomatoes?

The tomatoes planted by everyone are very prone to this situation under the conditions of ultra-low temperature, high and low temperature, and gradually produce the situation that the growers will generally see some small melasma and small vitiligo on the reverse side of the leaves of the tomato plant. This condition affects the normal development of leaf stems, mosaic stems and fruits of tomato plants. This type of pest and disease is commonly known as brown spot disease or spot disease, and it is very common to appear in tomato growing land.

Most of the causes of this disease are caused by long-term continuous cropping and low temperature frost damage.

In the early stage of the disease, the leaves are covered with small annular or irregularly shaped spots that expand along the petioles. The low-temperature frost lesions are spread along the leaf edge to the leaf axis, and the leaf color gradually turns yellow in the early stage, slowly producing black-brown lesions. The symptoms of a certain pest and disease of tomatoes are likely to be caused by various factors, or pathology, physiology, and nutrient deficiency.

For example, a person's general fatigue, which may be fatigue, starvation, organic diseases, or emotional effects, can all manifest as a condition.

Tomato gray mold is a very common leaf pest and disease, which is critical to the leaves, and sometimes also to the stems, flowers and fruits. In the early stage of the disease, irregular or oval green spots will appear on the front face of the leaves, and gray-white and dark red mold will appear on the reverse side, and the mold layer will change to gray-purple, dark gray or black or tan in the middle and late stages. In the case of high humidity in the field environment, mold layer will also grow on the front face of the leaves.

Due to the rapid development of the body's condition, the leaves will roll and wither. Similar lesions will appear in other locations, and gray-black fungi will grow in the middle and late stages. Spot blight also sometimes occurs on leaf stems and stems, and the lesions are oval-shaped, dark brown with black spots.

There are very few diseases on the fruit. Tomato spot blight is caused by suitable temperature and high humidity, and the disease is mild in high heat and low temperature environment; In addition, continuous cropping of tomatoes and low-lying areas have poor drainage pipes, too much irrigation, insufficient chemical fertilizer or rainy weather, and poor natural ventilation.

When planting tomatoes, if this happens, it means that the tomato is infected with a disease, and pesticides need to be used to prevent it. In addition, the main thing is to breed excellent varieties.

It may be caused by a lack of chemical fertilizer or insect disease, and it must be treated accordingly.

White spots on tomato leaves are infected with tomato spot blight. Spot blight mainly affects the leaves, stems and calyxes of tomatoes, especially on the leaves during the flowering and fruiting stage, and the fruit stalks and fruits are rarely damaged. Usually the old leaves near the ground are the first to become diseased, and then gradually spread to the upper leaves.

At the beginning of the disease, the back of the leaf appears water-stained small round class, and soon there are round and nearly round lesions on both sides of the front and back, the edge is dark brown, **gray-white, concave, generally 2 3 mm in diameter, dense black small spots (conidia).

Because the shape of the lesion is like a fish eye, it is called the fish eye spot disease. When the disease is severe, the leaves gradually wither and yellow, and the plants decay prematurely, resulting in early defoliation. The lesions on the stem are oval, brown, and the lesions on the fruit are brown and rounded.

Symptoms of leaf blight.

Produces small black spots on the lesions. Such as osmanthus leaf blight (also known as blight), plum leaf blight, aster leaf blight (also known as spot blight). The diseased leaves turn yellow at the beginning, and the yellow part gradually turns brown and dies.

It extends from local to the whole leaf vein, showing brown to reddish-brown leaf margin lesions, with wavy edges and dark color. The disease-healthy junction is pronounced, and the outer edge sometimes has a shallow yellow band of varying widths and narrowness, and then the lesion gradually extends to the base of the leaf until the whole leaf turns brown to grayish-brown. This is followed by the appearance of black villi or small black dots on the dorsal or frontal surface of the diseased leaves.

The hosts are mainly tomatoes, potatoes, cowpeas, lettuce, etc., which are mainly spread by seeds. In recent years, in the process of tomato disease investigation, we have found that the disease has occurred in Daxing in Beijing, Haicheng in Liaoning, Langfang and Baoding in Hebei, and Shouguang in Shandong. The main damage of tomato bacterial gray leaf spot is on leaves, stems, flowers, petioles and fruits.

The leaves are susceptible and then produce dark brown to black irregular spots, about 2 4 mm in diameter, with or without yellow halos around the spots. The petioles and stems have similar symptoms, producing black spots but no yellow halos around the lesions. The lesions are easy to connect into plaques, and in severe cases, a section of the stalk can turn black.

Sometimes the disease starts from the leaf margin, and expands to the inside of the leaf in an arc or V-shape, and under suitable humidity, the lesions are light brown to brown, and it is difficult to see the mold layer. The inside of the leaves is also diseased, with lesions light brown to brown with water-soaked edges, concentric rings, and gray mold layers on them. Dorsal lobe symptoms are similar to those on the front.

Tomato gray leaf spot is one of the main diseases of tomato, and the incidence of tomato gray leaf spot is 100% when it occurs severely, and if it is not controlled in time, it will have a great impact on the yield.

In the face of such an impact, we should actively take control measures, the leaves are covered with dark green round or non-round small spots at the beginning of the disease, and then spread along the leaf veins to the surrounding areas, forming an irregular shape, and the middle part fades green to gray-white to gray-brown. The lesions are slightly concave, mostly small, very thin, and are easy to crack and perforate in the later stage, resulting in broken or even falling off the leaves.

During the onset period, the fungus and bacteria are well killed, and it is generally cured after hitting it once, and it is OK to play again in 3-5 days. Because Tianlu Sterilization King is extracted from plants, it is non-toxic and has no residue, and can be picked at any time. At the beginning of the disease, spray 1000 times of 50% carbendazim wettable powder plus 1000 times of 75% chlorothalonil wettable powder, 800 900 times of 50% compound thiophanate-methyl wettable powder, spray once every 10 days or so, and continuously prevent and control 2 3 times.

You can go for basic copper sulfate. However, it should be sprayed twice. There is also a one-week interval. It can be better prevented.

At this time, it is necessary to water more, and prune off these spotted leaves in time, and spray some pesticides and apply some organic fertilizer.

The indoor temperature should not be too high, do not mix spraying when spraying the agent, strengthen the exhaust after watering, and spray the drug every other week or so.

You can go to the health station and buy the corresponding pesticide to spray it on the leaves, and he can eliminate this black spot, and then don't let it bask in too much sun, so that there will be no more spots.

It is recommended that the preferred drug is pyrazole naphthoxystrobin, and the added drugs are Chunlei King copper and basic copper sulfate. You can also spray benzoazoxystrobin 1000 times plus iprodione plus copper preparation, generally spraying twice, with an interval of 5-7 days.

The reason for this is probably due to the lack of nutrients in tomatoes, and at this time we should supplement him with some new nutrients and water them a little.

Tomatoes are one of the common vegetables on our table, but during the growth process, there are sometimes white spots on the leaves, why is that? The following will share with you the reasons why tomato leaves have white spots.

Lack of nutrients.

One of the reasons why white spots appear on tomato leaves is because it lacks certain nutrients. Plants need to absorb a lot of nutrients during growth, and if certain elements are missing in the soil, it will cause white spots on the leaves of the plant. Therefore, reasonable fertilization is an important step to ensure the healthy growth of plants.

Fungal infections. In addition to nutrient deficiencies, white spots on tomato leaves can also be caused by fungal infections. Fungal infections are one of the common causes of leaf lesions in plants, and severe fungal infections can lead to stunted plant growth and even death.

Therefore, it is necessary to strengthen pest control and carry out timely treatment of infected plants. At the same time, care should be taken to keep the growing environment dry and ventilated.

The temperature is too high or too low.

In the case of high temperatures in summer and low temperatures in winter, white spots appear on tomato leaves. This is because high temperatures will lead to increased transpiration of plants and increased loss of nutrients. Low temperatures may cause plants to freeze, and the growth of the plant may be affected. In order to avoid this problem, tomatoes should be cultivated in an environment with the right temperature.

Lack of light. While growing, plants need plenty of light for photosynthesis. The lack of light will result in white spots on the leaves. Therefore, it is important to provide tomatoes with sufficient sunlight or supplementary light sources to promote healthy plant growth.

Epilogue. The above is an introduction to the reasons for the appearance of white spots on tomato leaves. In daily planting, it is necessary to take the growth of the plant eggplant jujube seriously, and continuously observe and give feedback in a timely manner. In this way, our crops can grow healthier and stronger.

How to prevent white spots on the back of tomato leaves?

Tomato white spots may be paraquat drift. Generally, there is no major problem, and foliar sprays are applied with foliar fertilizer plus plant conditioner.

In fact, it is also caused by some bacterial infections, so at this time it is necessary to apply some chemical drugs to the plants**.

It is the plant that has pests and diseases, and the plant-specific insecticide should be used to spray evenly on the plant leaves, and it is not suitable to water during the medication, otherwise there is no effect, and it can be sprayed several times to consolidate it.

Tomatoes may be planted with yellow leaves in winter greenhouses for the following reasons:

1. The root system is not good.

2. Low temperature obstacles.

3. Insufficient fertilizer.

4. Nutrition can't keep up.

5. Pests and diseases.

The root system is not good: the nutrient bag is packed with nutrient sand, and the preparation method of nutrient sand is: 100 grams of fermented animal manure, 10 grams of urea, 3 grams of diammonium, 300 grams of sandy soil, and three small holes are pierced at the bottom of the bag, and the roots of the seedlings are packed into the nutrient bag, planted in the soil together, and the whole nutrient bag is buried, poured with water, and covered with soil.

It doesn't take a few days for the root system to develop, and soon the roots are thick and the leaves are vigorous.

Low temperature obstacles: Heat up the greenhouse in a timely manner, and try to match the growth characteristics of tomatoes.

1.Causes of white spots on tomato leaves.

Tomatoes are an easily cultivated vegetable and are often grown in home gardens. However, sometimes during the growth process, white spots appear on the leaves of tomatoes, which brings some trouble to the normal growth of the plant and the yield of the fruit. So, what is the cause of white spots on tomato leaves?

The answer is leaf spot. Leaf spot is one of the common diseases of tomatoes and is caused by the invasion of pathogenic fungi. In a warm and humid environment, the germs will multiply, destroy the cell tissues in the plant, and eventually lead to the appearance of white spots on the leaves.

2.How to prevent the occurrence of leaf spot.

In the process of planting tomatoes, we should pay attention to preventing the occurrence of leaf spot, which can effectively protect plant growth and improve yield.

First of all, healthy seeds and seedlings should be selected, and at the same time, the management of the grassland should be strengthened, and weeds and fallen leaves should be removed in a timely manner. Secondly, it is necessary to pay attention to controlling humidity and ventilation to ensure that the plant growth environment is dry and ventilated. Finally, some biopesticides can be used to spray to enhance the immunity in the plant and reduce the invasion of pathogenic bacteria.

3.How tomato leaves have white spots.

If white spots appear on the tomato leaves, we need to take steps to keep the plant growing properly. First of all, pesticides can be used for spraying, with the main purpose of killing pathogenic bacteria, but pay attention to the concentration and time of pesticide use to avoid unnecessary damage to plants.

Secondly, you can choose to prune the noisy bush to remove the diseased part on the leaf to reduce the spread and impact of the disease. Some farmers will also choose to use some natural methods of normalization, such as using ginger juice, garlic juice and other liquids to apply to the leaves to achieve the effect of antibacterial.

4.How to avoid the spread of disease.

In the process of white spots on tomato leaves, we should also pay attention to avoid the spread of the disease to prevent the disease from continuing to spread. First of all, it is necessary to strengthen the disinfection of the diseased parts, spray with 10% calcium chlorate and other agents to kill pathogenic bacteria, and replace the infected soil at the same time.

Second, care should be taken to avoid the spread of infection. When planting new tomatoes, it is best to choose seedlings that are in a healthy state to prevent the disease from continuing to spread. In addition, when handling and handling infected plants, Zheng Bi should pay attention to disinfection to prevent the spread of microorganisms.

5.Epilogue.

Through the above introduction, we can understand that tomato leaf white spot is a common disease caused by leaf spot. In order to prevent this phenomenon, we need to strengthen the management and maintenance of plants, and at the same time master some simple control methods to increase the growth and quality of plants. In our daily lives, we must also take care to avoid the spread of diseases in order to protect and maintain the environment of our vegetable garden.