Flower, fruit, wheat each kind of crop occurrence powdery mildew what medicine is better? What are the symptoms?

Powdery mildew is one of the main diseases of vegetables in summer. The disease is easy to occur in summer because of high temperature, stuffy humidity, improper fertilization, overgrowth of plants, poor ventilation and so on. What kind of medicine is better for powdery mildew? What are the symptoms?

Powdery mildew often occurs in the later stage of plant growth, which mainly harms leaves, but also leaves and stems. June-July is the peak period for melons, especially cucumbers, melons, watermelons and other melons.

Generally speaking, the genus of powdery mildew is different in different plants. Most powdery mildew pathogens can infect only one host plant, and only a few powdery mildew pathogens can infect many host plants. However, no matter which genus it is, the basic symptoms of the diseases are very similar.

Detailed explanation of powdery mildew of various crops:

1. Melon powdery mildew

Powdery mildew is one of the common diseases of melons. In recent years, powdery mildew has produced a certain degree of drug resistance, and it can occur all the year round, which brings some difficulties to the prevention and control. The production reduction is about 10% in the general year, and about 20% in the popular year.

The disease can be infected from seedling stage to harvest stage, which is mainly harmful to leaves, followed by petiole and stem vine. Generally do not infect melon strips. The infected leaves initially produced small white powdery spots on the back or front of the leaves, and then gradually expanded into irregular, inconspicuous white powdery mildew spots. With the development of the disease, the disease spot connected into a piece, covering the whole leaf, the injured part found chlorosis and yellowing, and there were many small black spots on the disease spot in the later stage of the disease. Finally, the white powdery mildew layer matures and turns gray. When the disease is serious, the diseased leaf tissue turns yellowish brown and dies. Under the condition of high humidity, the pathogen can also infect stem vines and flower organs, producing white powder spots, the symptoms are similar to leaves, the disease spot is small.

The peak period of melon powdery mildew was from the first half of April to the end of June. Damage to cucumbers in protected areas and autumn planting cucumbers also occurred from late September to the first and middle of November. The most suitable climatic condition for the disease is the temperature of 16-25 ℃ and the relative temperature of more than 80%. Cucumber cultivated in protected field has serious disease because of poor ventilation, high cultivation density, excessive application of nitrogen fertilizer and low-lying fields.

[prevention and control methods]

The main results are as follows: (1) selecting disease-resistant varieties.

(2) strengthen management. Reasonable close planting, trenching and drainage, timely removal of diseased leaves and old leaves, and strengthening ventilation and light transmission to enhance plant growth.

(3) Pesticide control. In the initial stage of the disease, timely spray prevention and treatment, once every 7-10 days, continuous prevention and treatment for 2-3 times, pay attention to alternate use. 80% gold ethyl pyrimidine can be used as the medicine. Spray control of 2500 times of nitrilazole wettable powder, or 4000 times of 40% flusilazole, 1500 times of 25% ethoxylate suspension, or 37% of difenoconazole 1500 times.

2. Strawberry powdery mildew

Strawberry powdery mildew is one of the most important diseases of strawberry. Strawberry can occur throughout the growing season, seedling disease caused by the decline of seedling quality, not easy to survive after transplantation; fruit infection seriously affected the quality of strawberry, resulting in a decline in the rate of finished products. Under suitable conditions, it can develop rapidly, spread into disasters and cause serious losses.

Strawberry powdery mildew mainly harms leaves, petioles, flowers, pedicels and fruits. In the early stage of the disease, a thin white mycelium layer grows on the back of the leaf. With the aggravation of the disease, the leaf curls upward in the shape of a spoon and produces dark stains of different sizes. Later, the disease spot gradually expands and produces a layer of thin frost-like white powder on the back of the leaf. In severe cases, multiple disease spots are connected into pieces, which can cover the whole leaf. In the later stage, it showed reddish-brown disease spot, leaf margin atrophied and scorched, buds and flowers were infected, petals were pink, buds could not open. If the fruit is infected, the young fruit can not be normally expanded and withered; if it is damaged in the later stage, the fruit is covered with a layer of white powder, with the aggravation of the disease, the fruit loses luster and hardens, and the coloring becomes worse, which seriously affects the berry quality and loses its commercial value.

The optimum temperature for bacterial infection was 15-25 ℃, and the relative humidity was more than 80%. The perennial peak period of strawberry powdery mildew in protected areas was from late February to early May and from late October to December. The sensitive growth period of strawberry is from fruit setting to late harvest, and the incubation period is 5-10 days. Compared with strawberries cultivated in open field, strawberries cultivated in protected field have earlier onset, longer damage time and more serious damage. Excessive planting density, extensive management, poor ventilation and light transmission, weak plant growth and so on can easily lead to the aggravation of powdery mildew. The disease was aggravated when high temperature and drought and high temperature and high humidity appeared alternately during strawberry growth.

[prevention and control methods]

(1) selecting disease-resistant varieties and cultivating disease-free and strong seedlings. There were great differences in resistance to powdery mildew among different strawberry varieties.

(2) strengthen cultivation management. The seedling field should be cleaned before planting, the old leaves and fruits of strawberries should be removed and destroyed in time during strawberry growth, good ventilation and light transmission conditions should be maintained, timely drainage after rain should be strengthened, fertilizer and water management should be strengthened, Jiamei dividend, Jiamei Hailibao, profit should be increased, and healthy plants should be cultivated.

(3) Pesticide control. The flowering period of strawberry before flowering in open field and the October-November and March-May of protected cultivation are the key periods for prevention. At the initial stage of the disease, Bayer Lunassen, ethosulfonate, Dow Yenong Karasen (36% nifedipine EC), Peruvian Krem, difenoconazole and tebuconazole were used alternately for prevention and treatment. Focus on spraying in and around the disease center, once every 7-10 days, continuous prevention and treatment 2-3 times.

3. Grape powdery mildew

The occurrence of grape powdery mildew is relatively common, and the epidemic years often cause great losses to fruit quality and yield. At the same time, it also affects the growth and development of branches and the growth and development of grapes in two years.

Powdery mildew can infect all green tissues of grapes. When the leaves were killed, there were chlorotic patches of different sizes, and then white powdery matter covered the disease spot. In the later stage, the leaf surface under the powder spot showed brown pattern, and when the leaf was serious, the leaf scorched and fell off. Sometimes there are small black spots on the disease. Young leaves often wrinkle, twist and develop slowly after being infected. After the ear axis was infected, the tissue became brittle and easy to break.

The young fruit is susceptible, the fruit surface is covered with white powder, the fruit grain is easy to wither and fall off, and some fruit surface appears dark brown reticular pattern. The diseased fruit stops growing, deformed, the pulp texture becomes hard, the taste is sour, and the fruit is easy to crack and rot.

The peak of the disease is in the young fruit stage after flowering. Muggy weather with high temperature and humidity is the most common, and foggy nights are very popular. Continuous rain or real high temperatures will stop the epidemic and occurrence of the disease. If the medicine is not strict before bagging, the mature fruit will crack due to powdery mildew infection.

[prevention and control methods]

(1) clear the garden thoroughly and burn the diseased branches and residual leaves cut off during winter pruning. Use 3-5 degree stone sulfur mixture before germination; the shelf surface is well ventilated and transparent; the central diseased plant, diseased shoot and diseased ear are removed in time, and bagged in time in the young fruit stage.

(2) 80% gold ethyl pyrimidine. The nitrilazole wettable powder has a special effect on the disease, and 80% gold ethosyl is available at the initial stage of the disease. Nitrilazole, or azoxystrobin, or nitrilazole spray control, medication time to avoid high temperature.

4. Eggplant powdery mildew

Eggplant powdery mildew is one of the common diseases of eggplant, which occurs in every vegetable area. Both open field cultivation and protected field cultivation can cause harm, but protected field cultivation is obviously more serious than open field cultivation. During the growth period, the disease was serious in years with warm and rainy weather. When the disease is serious, the positive and negative sides of the leaves are all covered with white powder.

Eggplant powdery mildew mainly harms leaves. At the initial stage of the disease, irregular chlorotic yellow spots appeared on the leaf surface, and white mildew spots appeared in the corresponding parts of the leaf back. After that, the number of disease spots increased, and the white powdery matter became increasingly obvious and showed powdery spots. White powdery spots can be connected to each other, spread all over the whole leaf surface, and in severe cases, the front and back sides of the leaves are all covered with white powder, resulting in yellow and dry leaves.

The most suitable climatic conditions for eggplant powdery mildew are temperature 16-24 ℃ and relative humidity 45-75%. When the relative humidity exceeds 95%, the development of the disease is restrained. The sensitive growth period of eggplant is in the flowering and fruiting stage. The disease is serious in the fields with low-lying terrain, poor drainage, poor crop growth, over-dense planting in continuous cropping and cultivation, poor ventilation and light transmission, and partial application of nitrogen fertilizer. During the year, the disease is serious in the warm and rainy years of spring and summer.

[prevention and control methods]

(1) Agricultural prevention and control. Rotation; selection of disease-resistant varieties; scientific fertilization to enhance plant disease resistance and stress resistance; reasonable close planting; ventilation, humidity reduction; timely removal of diseases, old leaves and diseased bodies.

(2) Pesticide control. Timely medication at the initial stage of the disease, once every 7-10 days, continuous prevention and treatment for 2-3 times, depending on the development of the disease, choose 80% gold ethyl pyrimidine. Nitrilazole, or azoxystrobin, or nitrilazole spray has a good control effect.

5. Powdery mildew of legumes

Bean powdery mildew mainly affects many kinds of vegetables, such as cowpea, pea, broad bean, lentil, kidney bean and so on. The disease is common in vegetable growing areas in the south, and has a great impact on yield when the disease is serious.

Powdery mildew of legumes mainly harms leaves as well as stems and pods. At the beginning of the disease of the leaves, there were round yellow-brown spots on the back, then expanded into irregular purple or brown spots, and produced a white powdery mildew layer on the back or surface of the leaves; in the later stage, the mildew layer was mature and grayish brown, and black spots were produced between the mildew layers. When it is serious, multiple disease spots connect with each other and expand into a powder belt along the leaf vein, and the disease spot also appears on the leaf surface, the color changes from white to grayish white to purplish brown, and walks through the whole leaf, resulting in rapid withering and yellow shedding of the leaf. Stem vines and pods are infected, resulting in a powdery mildew layer, which can dry up the stems and shrink the pods.

The bacteria prefer warm and humid environment, the suitable temperature range is 15-35 ℃, the most suitable climatic condition is 20-30 ℃, and the relative humidity is 40-95%. The most suitable susceptible growth period of crops is the middle and late stage of flowering and podding, and the incubation period of the disease is 3-7 days.

The peak period of legume powdery mildew was from May to November. The disease is serious in the years with high temperature and rainy years, alternating between dry and wet or with large temperature difference between day and night, and in the fields with continuous cropping for many years, low-lying topography, poor drainage, over-dense planting, poor ventilation and poor growth.

[prevention and control methods]

The main results are as follows: (1) select varieties with strong stress resistance; high border cultivation, reasonable close planting, ditch drainage, enhance plant growth, improve disease resistance; beat the old diseased leaves in time, remove the diseased remains in time after harvest, and take them out of the field for centralized destruction so as to reduce the source of bacteria in the field. Protected cultivation should be ventilated and ventilated.

(2) Pesticide control. 80% gold ethyl pyrimidine can be selected at the initial stage of the disease. Nitrilazole, or azoxystrobin, or nitrilazole spray control, once every 5-7 days, continuous control for 2-3 times.

6. Apple powdery mildew

Apple powdery mildew pathogen can not only harm apples, but also harm bauhinia, sand fruit, betel, begonia and so on. Apple powdery mildew mainly harms the twigs and leaves of apple trees, as well as buds, flowers and young fruits. After the seedlings are infected, the apical leaves and tender stems of the seedlings produce gray-white patches, such as covered with white powdery matter. When the disease is serious, the disease spot extends to the whole leaf, the diseased leaf atrophies, turns brown gradually and dies. After the tip of the new shoot was killed, the spreading leaves were slow, the extracted leaves were slender, purplish red, the top tip was twisted, and after the development stagnated, there were many dense black particles on the disease spot, especially in the tender stem and armpit.

When the temperature rises gradually in spring, reaching 21-25 ℃, and the relative humidity reaches more than 70%, it is conducive to the reproduction and spread of bacteria. The occurrence of apple powdery mildew was in the peak period from April to June, stagnated in the high temperature season from July to August, spread again on autumn shoots at the end of August, and declined gradually after September. The occurrence of the disease has two peak periods in a year, which is completely consistent with the new shoot growth period of apple trees.

The occurrence of apple powdery mildew is closely related to climatic conditions, cultivation conditions and varieties. The warm and dry years in spring are beneficial to the prevalence of the disease in the early stage, while rainy and cool in summer and sunny in autumn are beneficial to the disease in the later stage. Low-lying terrain, close planting in orchards, heavy soil viscosity, partial application of nitrogen fertilizer and insufficient potassium fertilizer, resulting in canopy closure and serious disease when the branches are weak. Extensive orchard management, improper pruning, inappropriate implementation of light cutting and long release, so that the increase in the number of bacteria-carrying buds will also aggravate the occurrence of powdery mildew.

[prevention and control methods]

The main results are as follows: (1) strengthen cultivation management, adopt formula fertilization, avoid partial application of nitrogen fertilizer, make fruit trees grow healthily and control irrigation.

(2) cleaning the countryside, combined with winter pruning, cutting off diseased shoots and diseased buds; re-pruning in early spring, cutting off newly diseased branches, concentrated burning or deep burial to prevent conidia from spreading.

(3) Chemical control, spraying protective agents before germination; 80% gold ethyl pyrimidine was selected at the early stage of the disease in spring. Nitrilazole, or azoxystrobin, or nitrilazole spray control, 10-20 days once, a total of 3-4 times.

7. Flower powdery mildew

Flowers have high economic value. Powdery mildew is an important disease in flower planting. In recent years, powdery mildew occurs seriously in rose and other flowers, and the occurrence area of each flower producing area is getting larger and larger year by year.

The suitable temperature for the occurrence of flower powdery mildew is 15-25 ℃. Powdery mildew can spread no matter in dry environment or in high humidity.

[prevention and control methods]

The medicament can be selected as 80% gold ethyl pyrimidine. Nitrilazole, or azoxystrobin, or nitrilazole spray has a good effect on powdery mildew of all kinds of flowers such as rose.

8. Powdery mildew of traditional Chinese medicine

In the cultivation of Chinese medicinal materials, powdery mildew is an important disease in production. In recent years, powdery mildew has seriously occurred in Schisandra chinensis, Angelica sinensis, Radix Astragali, Lycium barbarum, Panax notoginseng and other Chinese medicinal materials.

The suitable temperature for the occurrence of powdery mildew in traditional Chinese medicine is 15-25 ℃. Powdery mildew can spread no matter in dry environment or in high humidity.

[prevention and control methods]

80% gold ethyl pyrimidine was selected at the initial stage of the disease. Nitrilazole, or azoxystrobin, or nitrilazole spray control.

9. Mango powdery mildew

Mango powdery mildew occurred in Hainan, Guangdong, Guangxi and Yunnan. It can harm the inflorescences, tender leaves, shoots and young fruits of mango, and some scattered powdery disease spots begin to appear on the surface of these young tissues, and then the tissue under the disease spots is necrotic to form brown scars. After the inflorescence is damaged, the flowers stop opening, the pedicels no longer stretch, and then wither, dry, blacken and fall off. Young leaves often twist and fall off. Fruit drop is caused by young fruit damage, and massive disease scars are often formed on larger young fruits.

The disease can occur at 9-32 ℃ and 0-100% relative humidity, and the outbreak temperature is about 23 ℃. The pathogen often survives on the old diseased leaves that pull out shoots late and become the source of primary infection. The following spring, with the help of the wind to spread to the new tender leaves and inflorescences, the disease is easy to occur and epidemic due to the high humidity, cloudy and low night temperature during the flowering period of mango leaves from February to April every year.

[prevention and control methods]

On the basis of strengthening cultivation management, timely spraying control. In general, the disease can be controlled by spraying once in the flower cluster extension stage, flowering stage and fertile stage, but it needs to be sprayed once every 7 days in the severe disease area or serious infection year to increase the spraying times. Make up the spray when it rains after spraying. 80% gold ethyl pyrimidine can be used as the medicine. 2500 times solution of nitrilazole wettable powder has a special effect on the control of mango powdery mildew.

10. Wheat powdery mildew

Symptoms of damage: at the beginning of the disease, white mildew spots appeared on the leaf surface, and then gradually expanded into nearly round to oval white mildew spots, with a layer of white powder on the surface of the mildew spots, which scattered immediately in case of external force or vibration.

These powders are the mycelium and conidia of the bacteria. In the later stage, the mildew layer of the disease became grayish white to light brown, and there were small black spots the size of needles, that is, the closed capsule of the pathogen.

The peak period of the disease: from mid-late March to late April, there are differences in different regions.

[prevention and control methods]

(1) selecting disease-resistant varieties.

(2) promote the application of compost or mature organic fertilizer retted by enzyme bacteria, adopt the technology of formula fertilization, properly increase the application of phosphorus and potassium fertilizer, and plant closely according to the characteristics of varieties and soil fertility. Timely drainage after rain in the wheat area of southern China to prevent moisture retention. The wheat area in northern China was watered at the right time to enhance the disease resistance of the host.

(3) in the over-summer area of authigenic wheat seedlings, winter wheat should be cleared in time before autumn sowing, which can greatly reduce the bacterial source of autumn seedlings.

(4) at present, the effective therapeutic agents for the prevention and treatment of powdery mildew in the market are: heterocyclic (ethylol, ethosulfonate), triazoles (triadimefon, hexazolol, propiconazole, tebuconazole, fluconazole, etc.) and methoxyacrylate (azoxystrobin, ether carbendazim, etc.).

1. Heterocyclic ethoxylate and ethosulfonate have good control effect, but the resistance is too fast.

2. Triazole drugs such as hexazolol, tebuconazole and fluconazole have good preventive effect on wheat powdery mildew, and the therapeutic effect is unstable. This kind of drug can be used to control wheat powdery mildew in the early stage. At present, wheat powdery mildew pathogen in many areas has strong resistance to triazole fungicides such as triadimefon, tebuconazole and hexazolol, even if the dosage is greatly increased, the control effect on powdery mildew is not stable enough.

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