How to treat tomato leaf mildew? How to prevent and control tomato leaf mildew and what medicine sho

How to prevent and control tomato leaf mildew.

1. Reasonable crop rotation: more than three years of crop rotation for non-solanaceae crops to reduce the number of bacteria in the soil.

2. Seed disinfection: disease-free seeds can alleviate the initial infection caused by seed carriers in the field. The introduction of seeds requires seed treatment and soaking in warm water.

Taking advantage of the difference in heat tolerance between seeds and pathogens, the temperature that can kill the internal and external pathogens of the seeds without damaging the vitality of the seeds is selected for disinfection. For tomato seeds cultivated in greenhouses, it is advisable to soak seeds in 55 warm water for 30 minutes to remove germs inside and outside the seeds, cool them in cold water after taking them out, soak them in potassium permanganate for 30 minutes, rinse them with water several times after taking out the seeds, and finally dry them to promote germination and sowing.

3. High temperature stuffy shed: choose the noon time of a sunny day, take about two hours of 30 33 high temperature treatment, and then ventilate and cool down in time, which has a good control effect on pathogenic bacteria.

4. Strengthen shed management: timely ventilation, proper control of watering, timely ventilation and humidity reduction after watering; In addition to increasing soil moisture, the cultivation method of double ridge mulching and irrigation under film can significantly reduce the air humidity in the greenhouse, thereby inhibiting the occurrence and re-infection of tomato leaf mold, and the mulching can effectively prevent the spread of pathogens in the soil. According to the weather conditions outside the greenhouse, the humidity and foliar condensation time in the greenhouse can be reduced as much as possible through reasonable ventilation, which has a certain control effect on the disease.

Pruning and pruning in time, removing the leaves of the lower part of the plant as much as possible, and increasing ventilation. Implement formula fertilization, avoid excessive nitrogen fertilizer, and appropriately increase phosphorus and potassium fertilizer.

5. Select disease-resistant varieties and strictly control seedlings; Among the varieties promoted in the market, there are Jiafen 15, Jiafen 16, Jiafen 17, Zhongza 7, Shenfen 3, Jiahong 15, etc., which can be planted according to local conditions.

Summary. Tomato leaf mildew is one of the most common diseases. During the planting process, the seeds can be sterilized before planting. Ventilation should be strengthened after watering. Especially after the rainy season, it should be drained in time to reduce the occurrence of diseases.

Tomato leaf mildew is one of the most common diseases. During the planting process, the seeds can be sterilized before planting. Ventilation should be strengthened after watering. Especially after the rainy season, it should be drained in time to reduce the occurrence of diseases.

If it is already sick, you can spray leaf mold, anti-mildew or Garinone, etc. It can also be sprayed with 60% carbendazim hydrochloride 600 times.

Tomato leaf mildew is a disease that can easily occur, and once the disease is difficult to control, its resistance will gradually increase with the increase of the number of medications. When sprayed, the spores are also dispersed in the air and transferred to other leaves with the airflow for reinfection. Therefore, leaf mold control should be carried out early.

Use of broad-spectrum fungicides.

chlorothalonil (Daknin), primehydin (iprodione), methyl tobuzin, etc. This good accompaniment to the vertical drug has the advantages of broad spectrum, safety, low cost, good preventive effect, etc., but the efficacy is not very good, should be used before the onset of the disease, or combined with the use of drugs with outstanding efficacy.

Use of azoles.

Myclobutazole (Xiansheng), fluconazole (Tefulin), difenoconazole (Shigao) and other drugs have the advantages of significant efficacy, low dosage, strong water absorption and long effective time. But the use of drugs can inhibit the growth of crops. If the number of consecutive drug users is more than three times, it may cause the tomato leaves to become smaller, harder, brittle, messy and blacker, etc., so it must be used with caution, especially in the low temperature period of winter, especially in the low temperature period of winter, in addition to the world height.

When using this agent, it can be combined with growth regulators such as bruscinolide (shidai, yunda120, etc.), cytomitogen, etc., to reduce the risk of brassinolide on tomato growth.

Antibiotics.

Chunleimycin, polyantimycin, agricultural anti-120, etc. These agents are safe, broad-spectrum, strong systemic and have outstanding preventive effects, but the best effects are poor.

According to the characteristics of the above-mentioned agents, the following drugs should be used for the prevention and control of tomato leaf mold: when the leaves have no disease spots or the incidence rate is less than 5%, broad-spectrum fungicides can be used, and higher antibiotic fungicides or mixed antibiotic fungicides can also be used. When the incidence is greater than 5% and there is a tendency to spread, azole fungicides should be selected.

Of course, it is necessary to work with brucilactones, mitogen, and other plant growth regulators. When the disease is particularly severe, azoles can be mixed with broad-spectrum agents or antibiotics for comprehensive prevention and control.

Symptoms: Oval or irregularly shaped pale green or pale yellow pale green spots appear on the front of the leaf when the leaf is damaged, until the whole leaf is yellow. The back of the leaf forms nearly round or irregular white mold, and when the disease is severe, the mold is covered with the back of the leaf, and the color changes to gray-purple or dark green, causing the whole leaf to gradually curl from bottom to top.

The fruit is damaged, and black hard lesions are formed around the pedicle, and the pedicle is slightly concave downward. The flowers become moldy and die after being damaged. Symptoms on petioles and young stems are similar to those on leaves.

Leaf mold control methods: choose disease-resistant varieties. Such as Jiafen No. 15, Jinpeng No. 1, Zhongza No. 9, Dongnong 712, Dongnong 708, etc.

Shed disinfection. Before planting, 2 grams of sulfur powder per cubic meter of space plus 4 5 kg of sawdust, and the dark fire behind the closed shed is lit for 24 hours, and then ventilated for 24 hours, and the tomato can be planted. Ecological prevention and control.

Strengthen the management of room temperature and humidity in the shed, ventilate in a timely manner, and control watering appropriately. Pharmaceutical prevention and control. Spraying 50% iprodione 1000 times solution, or 60% carbendazim hydrochloride 600 times solution, the control effect is better.

Diseased leaves and fruits of tomato gray mold (infected) by stigma

The following measures are mainly taken to control tomato leaf mildew:

First, variety selection and seed treatment.

There are many physiological races of this pathogen, and disease-resistant varieties should be selected according to the dominant physiological races. Choose disease-free seeds, soak the seeds in 53 warm water for 30 minutes before sowing, dry and sow seeds.

Second, agricultural prevention and control.

In areas with severe disease, crop rotation should be implemented with non-solanaceae crops for more than 3 years to reduce the source of primary infection. The seedbed should be replaced with new disease-free soil. Using old beds, the soil should be disinfected by spraying 500 times of 50% carbendazim wettable powder before sowing.

Seriously ill greenhouses and greenhouses should be disinfected before planting, that is, after being sealed, they should be used every 100 meters with 2 kilograms of sulfur and sawdust, and then mixed into several piles and ignited for fumigation for 1 night. Strengthen cultivation management. Timely ventilation, proper control of watering, and timely drainage of moisture after water, forming warm and humid conditions that are not conducive to the occurrence of diseases.

Do not irrigate before flowering, lightly irrigate when flowering, and re-irrigate after fruiting. Do a good job of heat preservation in the early stage, strengthen ventilation in the later stage, and remove old and diseased leaves. When the disease progresses, you can choose a sunny day at noon, and the temperature rises to 36 38 in a closed shed, and it can be maintained for 2 hours to inhibit the progression of the disease.

Third, pharmaceutical prevention and control.

At the beginning of the disease, 45% chlorothalonil smoke agent was smoked overnight with 250 300 grams per 667 m2 each time or 5% chlorothalonil dust agent was sprayed in the evening, 1 kg per 667 m2 each time, sprayed once every 8 10 days, and applied continuously or alternately. It can also be sprayed at the beginning of the disease with 47% 50% Chunlei Wangtong wettable powder 500 times, 10% difenoconazole 1000 times, 2% Wuyi aqueous 100 150 times, 70% thiophanate-methyl wettable powder 800 1000 times, 50 65 liters per 667 meters 2 sprays of good solution, sprayed once every 7 10 days, and continuously controlled 2 3 times.

Symptoms: Tomato leaf mildew does not infect fruits, but mainly tomato leaves. In the early stage, there are some green spots on the back of the leaves, and in the later stage, gray or black-purple irregular mold layers are bred on the lesions, which are commonly known as "black hair" by the common people, and the front of the leaves fades green and yellow in the corresponding parts, and when it is serious, the leaves often appear dry and curled.

Leaf mold usually spreads from the lower leaves of the plant, and is generally prone to disease when the temperature of the shed is 20 25 and the relative humidity is about 85%. In the environment of weak light, poor ventilation and excessive humidity on cloudy days, leaf mold occurs especially seriously. The disease seriously affects the physiological function of leaves and can lead to a significant reduction in tomato yield.

Prevention and control measures: before transplanting seedlings, use 45% chlorothalonil tobacco agent for indoor disinfection, timely drug prevention and control in the early stage of the disease, dust method or smoke fumigation, 5% Garinon dust agent, 45% chlorothalonil smoke agent can be used. Spray should be carried out in the morning, pay attention to the leaf back medicine, you can choose 10% Shigao water dispersible granules 1000 times liquid, 2% Wuyimycin water 150 times liquid, 60% anti-mildew Bao ultrafine powder 600 times liquid, 47% Garinon wettable powder 600 800 times liquid and other sprays, spray 1 time in 7 8 days, spray 3 times in a row, pay attention to alternate medication, to prevent drug resistance.

When spraying, vegetable farmers should pay attention to the key spraying parts. The fungus of leaf mold is to survive on diseased residues in the soil, and tomato leaf mold begins to develop in the lower leaves of the plant. Tomatoes at the foot of the shed near the south side of a shed are the first to become ill, so it is important to focus on the lower leaves of the plants and the plants on the south side of the greenhouse when spraying before the onset of the disease.

After the onset of the disease, the spraying should focus on protecting the functional leaves of the middle and upper parts of the plant.

Note: Tomato leaf mildew is very easy to break out, once the disease is difficult to prevent, and with the increase of the number of medications, its resistance will gradually increase. When spraying, the spores on the lesions will also be dispersed, allowing them to diffuse into the air and transfer to other leaves for re-infection.

Therefore, the prevention and control of leaf mold should be early, and the most critical period is in the first to second panicle flower setting period of tomato, which should focus on prevention, and spray pesticides every 7 days. Once the lower leaves have been found to be diseased, it is necessary to spray the best agent in time, and the earlier the same agent is prevented, the better the effect will be.

We need to rotate the land effectively and reasonably, so that the number of bacteria in the soil can be reduced.

When choosing tomato varieties, it is necessary to strictly control and choose excellent leaf mold resistant varieties (such as Jiafen 15, Zhongza 7, Jiahong 15, etc.).

To disinfect the seeds before planting, you can soak the seeds in warm water at 55 degrees for half an hour, which can effectively remove germs inside and outside the seeds. After the excess, soak the seeds with potassium permanganate for half an hour, and finally rinse them well.

Leaf mold generally starts from the lower leaves, and gradually expands to the upper leaves, the front of the leaves first appears irregular light yellow green spots, the back of the leaves initially grow a white mold layer, and then become gray-brown or black-brown mold layer, and the front of the leaves can also grow black mold in the later stage.

The temperature is 22 degrees, the humidity is greater than 90% is conducive to the occurrence of leaf mold, high temperature and high humidity is the favorable conditions for the occurrence of leaf mold, when the temperature is above 33 degrees has the effect of inhibiting the pathogen, you can consider the appropriate high temperature baking shed.

The choice of agent is recommended to use polyantimycin or pyroxazole or acridium amide or pythium or pyrimethricyclamine or azoxystrobin plus tebuconazole, or benzazoxystrobin or lunasen or chunleimycin spray should be uniform, the amount of water should be sufficient, and it is best to add foliar fertilizer to restore the damaged foliage.

Tomato leaf mildew mainly damages leaves, and can also damage stems, flowers and fruits in severe cases. The leaves are infected, the leaf surface appears irregularly shaped light yellow green spots, the back of the leaf initially grows white mold, and then becomes gray-brown or black-brown, and the front of the leaf can also appear gray-brown mold layer when wet, with the development of the disease, the leaves are gradually curled from the bottom to the top, and the plant is yellow-brown and dry.

The causative agent of leaf mold is the subphylum Semi-Knowitives fungi and C. xanthospora.

For prevention and control, Lepudao (bactericidal pill + tebuconazole), Echo (dimethomycmine + tebuconazole) or 40% difenoconazole, Wanxing (flusilazole + oxazolodione), 70% methyl or 25% amicida suspension 2000 times, or 30% Aimiao EC 4000 times, or 50% Kaiser water sprinkle 1500 times, or 60% anti-mold treasure ultrafine powder 600 times and other liquid medicines. Once every 7-10 days, spray 2-3 times continuously. In case of cloudy and snowy weather, use dust or fog agent instead.

Spray activated iodine, which is said to be very effective.

Prevention and control measures.

1) Selection of disease-resistant varieties. If Bi-Antibody No. 2 is more resistant to leaf mold, but not to gray mold and early blight, it can be appropriately selected according to local conditions. (2) Strengthen cultivation management.

Pay attention to ventilation and moisture drainage, and remove the lower diseased leaves and old leaves in time to facilitate ventilation and light transmission. Properly control watering, and ventilate and drain moisture in time after watering. Proper dense planting, timely pruning and pruning.

3) Prevention and control of pesticides in protected areas. In the early stage of the disease, fumigation or dust agent can be used to fumigate the greenhouse or greenhouse, close the shed before seedling planting, use sulfur kilograms and sawdust kilograms per 55 cubic meters of space, and ignite and fumigate with charcoal for 24 hours after mixing. It can also be used with 45% chlorothalonil smoke agent, 250 300 grams per mu each time, smoked overnight, or sprayed in the evening with 7% leaf mold net dust agent or 5% chlorothalonil dust agent, or 10% ditropium powder, 1 kg per mu each time, sprayed once every 8 10 days.

Several agents can be used continuously or alternately.