In early spring, the low-temperature and high-humidity greenhouse environment created suitable conditions for the disease. At present, it is at the peak of the occurrence of gray mold, and once it occurs, it is the number one killer of vegetable pests and diseases in greenhouses because of its large spores and fast propagation, and it is even hard to prevent it. ".
So, how should we control gray mold? In this issue of the â€œPlant Protection Hospital,â€ we will focus on the comprehensive prevention and control of gray mold for reference by farmers. Lifting temperature and preventing gray mold
Gray mold is difficult to control, one of the reasons: low temperature and high humidity.
Gray mold is a low temperature and high humidity type disease, and its temperature is suitable for 20-25Â°C. However, due to the suitable temperature for disease onset, which is close to the optimum temperature for the growth of most greenhouse vegetables, it is difficult to control the occurrence of gray mold by managing the temperature alone, and it is necessary to carry out the combination of dehumidification.
Botrytis cinerea requires strict humidity. When the relative humidity of the air reaches above 90%, it is easy to develop. The high humidity maintains a long time and the disease is severe. The relatively high relative humidity in the shed is the dominant factor in the occurrence and spread of the disease. Especially in periods of heavy rain, low temperatures, untimely ventilation, and high humidity in the shed can cause sudden outbreak and spread of gray mold.
Based on the above theoretical basis, we can control temperature and humidity so as to prevent and control gray mold.
The air was released late in the morning, and it began to go over 30Â°C. During periods when the relative humidity in the shed is high, try to increase the temperature of the shed and avoid the temperature of the disease.
When the temperature dropped to 25Â°C, it continued to vent at noon. Reduce the humidity in the shelter and avoid the damage caused by high humidity.
In the afternoon, the temperature is maintained at 20-25Â°C. When the temperature is released to 20Â°C, the ventilation is stopped. The purpose is to keep the night temperature at 15-18Â°C. During the period with the highest relative humidity in the shed, the optimum temperature of gray mold is avoided. .
What needs special emphasis is: during the cloudy days, ventilation should be conducted at noon.
However, the above-mentioned ventilation measures are not suitable for legumes and vegetables, especially for legumes that are in early flowering stages, and management needs attention.
In addition, the release of effluent is actually only a part of reducing the humidity in the shed. It is also necessary to control the humidity in the shed by measures such as pouring a small ditch under the membrane, pouring a small amount of water, planting a mulching mulch, and manipulating mulching with rice straw. Clearing the disease-proof gray mold
Gray mold is difficult to control, the second reason: strong saprophytic.
Botrytis cinerea is a semi-mycotic fungus Botrytis cinerea, which has weak parasitic ability and strong rot ability. In other words, gray mold begins to invade from dead parts such as dead branches, rotten leaves and streaks. Therefore, prevention and control of gray mold should remove the diseased body and cut off the channels of infection by Botrytis cinerea.
First of all, we must remove the stray flowers.
Residual flowers are the main source of infestation for gray mold. Most of the rot caused by gray mold begins with streaks. Therefore, we must remove the residual flowers in time, including those that remain on the fruits and those that fall on the stems and leaves. In particular, crops such as cherry tomatoes and cowpea which have a large amount of flowering.
After the cherry tomato fruit is seated, many petal cannot fall off normally, but close to the calyx, which requires the vegetable farmer to "pick up" the flower. However, when picking up flowers, it is important to note that do not pick flowers after the fruit is sitting. This will cause the skin of the fruit to scratch the skin and cause the next fruit to form. Generally, it is sufficient to pick flowers when the fruit is sitting on the size of soybeans. At the same time, be careful when picking flowers.
Kidney beans and other legumes, the petals do not fall off, mostly attached to the top of the fruit, generally use "shake" flowers. "Shake" the flower, that is shake the plant to help off the flower.
At the same time, sheds must be picked up for residual flowers that fall on the stems and leaves and on the ground.
In addition, for silky gourd, cucumber and other crops, you can add iprodione 300 times (available also fludioxonil) in anthers, in order to increase the amount of drug, you can add 500 times neutral detergent in the liquid , to increase efficacy.
Second, we must remove old leaves, yellow leaves, rotten leaves, and dead branches.
This is an important task in the adjustment of plants. Its significance is that although these stems and leaves do not consume nutrients, they are easily infected and become a source of infection.
It should be noted that this work should be carried out on a sunny day, and a fungicide should be sprayed after the stems and leaves are removed to prevent germs from infecting the infected stems and dead stems. Streptomycin can be sprayed 3000 times for prevention.
Again, we must properly remove the gray mold or diseased leaves. The vegetable growers understand that the removal of botrytis cinereus in order to control the spread of gray mold disease. However, in actual production, many growers easily remove the spores of Botrytis cinerea when removing the botrytis cinerea residues on the plants. These botrytis spores are shaken off in the air and transmitted again through the air. Therefore, when the tissue infected with the gray mold is removed, it can be burned with a lighter or wrapped in a small bag and cleaned.
In the end, we must also remind the vegetable farmers: Do not put the above-mentioned diseased bodies in the shed. Take it out of the shed and concentrate on it. Smell and cure combined with gray mold
Gray mold is difficult to control, the third reason: a large amount of pathogenic spores.
We see the gray moldy layer of dense parts of the diseased area, that is, the pathogenic spores of gray mold. These pathogenic spores can spread with the wind, agricultural operations, and other re-infection. In production, some farmers often rely solely on spraying to control gray mold. Therefore, there is the aforementioned â€œpreventionâ€. The main reasons for analyzing the reasons are as follows:
First, the liquid is sprayed on the bacteria. At the same time, the spores are not sprayed because of the large amount of spores. Therefore, the spread of some germs was also helped. Especially in the sheltered fields and luxuriant sheds, this situation is even more pronounced.
Second, while spraying, it also increases the relative humidity inside the shed, which, to a certain extent, creates conditions for the occurrence and spread of germs.
Third, in the event of a cloudy day, it is not advisable to use spraying to prevent botrytis (because it is not only easy to reduce the efficacy, but also there is a danger of liquid medicine adhering to the plants for too long), and it cannot be allowed to develop.
Therefore, control of gray mold can not rely solely on spraying, but also with smoke.
Compared with spraying, the smoke will not only increase the humidity in the greenhouse, but also reduce the humidity in the greenhouse. The smoke will be fully sterilized and can be used for sterilization in the whole greenhouse. Combine spraying with fumigation and learn from each other to control the occurrence and development of gray mold.
Spraying: In sunny weather, dry leaves can be sprayed in the afternoon or in the afternoon, but no medications are allowed at noon high temperature to prevent phytotoxicity.
Drugs can be selected from 1500 times prodigiosin, 1,000 times pyrimethanil, 800 times nicotinamide, 1,000 times the amount of cyprodinil and 800 times the yield of vinyl sclerotin.
Smoke: Smoke can be applied before closing the shed in the evening, or it can be smoked on a cloudy day.
Optional smoke speed smoke agent, stencil net smoke agent.
Under normal circumstances, spraying and smoking smoke alternately, or spray the second drug, smoked a drug. If the occurrence of gray mold is heavy, then spraying and fumigation can be combined for prevention and treatment, that is, spraying during the day and smoking in the evening.
In addition, it should also be noted that whether it is pharmaceuticals or smoke, it should be selected according to the different crops. For example, eggplant and leguminous vegetables are sensitive to pyrimethanil. Therefore, when selecting pharmaceuticals, other pharmaceuticals should be selected as much as possible. These two types of crops are also sensitive to sclerotia. Therefore, they must be strictly controlled in the amount of smoking time and smoking time. The safe amount is 200 g/mu and the smoke time is about 8 hours. Rotational treatment of gray mold
Gray mold refractory, the fourth reason: repeated medication.
There are many friends of vegetable farmers, "what kind of medicine is good, what kind of medicine will be used in the end" approach, repeated drug use is particularly serious.
The agents used to treat Botrytis cinerea are mostly systemic. After continuous spraying 2-3 times, the pathogens are susceptible to drug resistance, and the effect of preventing and controlling botrytis is greatly reduced. Even if the dosage is increased, it is difficult to achieve an ideal control effect. . This is also the real reason why vegetable farmers often say that "smoke has been sprayed with certain drugs and no effect has been seen." Therefore, when using drugs to control botrytis, it is necessary to alternate medications or mixed medications to avoid repeated medications.
Here we are referring to the repeated use of drugs, not just the same name of the drug, but also the name of the drug is not the same, but the active ingredient is the same drug. For example, pyrimethanil is also known as Shijiale, iprodione urea is also known as punhaiin and so on.
Currently used in the market to kill gray mold have sclerotia net, procymidone, iprodione, pyrimethanil, cyprodinil, nicotinamide, oxazole and so on. In order to prevent drug resistance and improve control efficiency, it is recommended that the vegetable farmer rotate alternately or use it rationally.
Before the onset of disease: 1000 to 1500 times of procymidone and 1000 to 1500 times of iprodione are alternately sprayed alternately; spraying with chlorothalonil or a copper agent can also be used to prevent the occurrence of gray mold, avoiding repeated use of the drug, and preventing Poor conditions occur.
In the early stage of disease, it can be used for drug alternation with 800 times of bacteriostatic bacteria (Nongliling), 1000 times of pyrimidine cyclic amine (and Rui), 1000 times of pyrimethanil (Scarlet), and 2500 times of oxazole (Bactera). Medication spray.
The peak period of onset: The use of procymidone or iprodione for the prevention and treatment of the disease at the initial stage of application. Prevention of Botrytis cinerea Four attention to "prevention as the main, comprehensive prevention and control" is the policy of plant protection, and it should be the case for the rapid and harmful botrytis disease, and follow the prevention and treatment methods of "disease-free early prevention, disease early management".
Apart from the above-mentioned prevention and control measures, the following four points should also be taken into consideration when controlling gray mold:
Note one: Grab three timings.
1. Before planting: Disinfect the whole shed to kill the pathogens that remain in the shed, and lay the foundation for the effective control of gray mold in the later period. The method may be sprayed with quick keratin and acetaminophen, etc. in the whole shed to control botrytis cinerea, and smoke-applying 100-speed smoke agent.
2. Flowering: Apply early to avoid infestation from corrupted petals. Now that we have mastered the law of the infection of Botrytis cinerea from the petals, it should be controlled as soon as possible so that the gray mold will not occur.
3. Fruit enlargement period: fruit enlargement period, nutrient concentration of the supply of fruit growth, easy to stem and leaf lack of nutrients and reduce disease resistance; at the same time, because the fruit enlargement period requires a large amount of water, easy to form a high humidity environment, so this period is also The key opportunity to control gray mold.
Note 2: When the gray mold occurs, reduce the ventilation and treat the disease first.
Ventilation is conducive to the transmission of Botrytis cinerea. In the event of major gray mold, ventilation should be as little as possible or not ventilated, after the control of the disease, then normal ventilation, so as not to cause the flooding of gray mold, no prevention.
Note 3: Change the number of medications, rational drug control.
Generally speaking, 7-10 days is the interval between medications, but the interval needs to be determined according to the growing situation of the vegetables in the greenhouse. If the plants grow robustly, they can use the medicine once every 10-15 days; if the disease is severe, it should be In the case of rational drug use, the interval of shortening is about once every five days, and prevention and treatment are carried out continuously to facilitate the effective control of the occurrence of diseases.
Note 4: Watch the weather forecast in a timely manner and promptly take medication before the onset of rainy weather.
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