At present, the north is about to enter the severe winter season. It is the early stage of flowering and fruiting of solanaceous vegetables in greenhouses. It is also a critical period for greenhouse management and disease prevention. For this reason, the reporter specially organized this draft to help distributors and farmers do a good job in greenhouse disease management and improve economic efficiency.
1. Three major causes of greenhouse diseases
First of all, temperature and humidity management mistakes. The vast majority of vegetable farmers began to ventilate around 10:00 am and closed the air outlets in the morning and at night, resulting in low temperature in the greenhouse and high relative humidity in the air. The most suitable temperature for the development of most diseases is 15-26°C. In this way, the temperature in the shed is about 20°C for a long time, and the humidity is above 90%, which is exactly the most suitable for the occurrence of diseases.
Second, low temperature management results in low soil temperatures. Under this management model, the soil temperature is about 20°C or even lower for a long time. Low soil temperature, poor root development, affect the absorption capacity, resulting in poor plant resistance. Resolving various kinds of diseases from the "root" is exactly what the agricultural experts have always advocated. Only when it is healthy, can it be flourished, and then fundamentally improve the resistance of the crops to resist diseases.
Secondly, the pathogens were not eradicated and controlled in a timely and thorough manner. This point has been made better and better with the improvement of the pest control awareness of vegetable farmers. In some mature planting areas, almost no diseased leaves, diseased fruits, and creeping vines have been found in greenhouses. However, it is worth noting that even if these are cleared out of greenhouses, they need to be buried in time, be fattened or burned, because when the greenhouse is ventilated, germs can also be introduced into the shed from the outlet, causing recurrence.
2 temperature and humidity control is the best way to prevent disease
In addition to regular spraying of protective fungicides at safety intervals, the creation of a high-temperature, low-humidity ecological environment is the most important, and it is also the main measure of ecological control. In general, the humidity of the greenhouse is higher than 90% at night. Immediately after pulling haystacks in the morning, ventilates should be opened and ventilated. After 9 o'clock, when the temperature in the shed increases, the vents are closed, and the temperature inside the shed is rapidly raised to 2-3 degrees Celsius above the maximum temperature for crop growth, and this temperature is maintained until 15-16 hours. After 15-16 hours, gradually increase the ventilation openings to accelerate the humidity. Before covering grasshoppers, as long as the temperature in the shed is not lower than 16°C, the ventilation openings should be increased as much as possible; if the temperature is lower than 16°C, the ventilation openings should be closed in time to keep warm. In addition, under the premise of ensuring that the temperature in the early morning shed is not lower than 10°C, the air outlet can be opened again from below the grasshopper at around 21-22°C to minimize the humidity in the shed. In the above-mentioned temperature and humidity control process, when the temperature is high, the humidity is low, and when the humidity is high, the temperature is low, which can effectively suppress the occurrence of the disease, and reduce the number of times of administration and the amount of medication.
3. Reasonably adjust the vegetable market
Generally speaking, the price of vegetables before and after the Spring Festival is the highest in a year. Therefore, the cultivation of solanaceous vegetables can be adjusted appropriately so that it can reach the peak of harvest before and after the Spring Festival. The specific method can be achieved by adjusting the sowing date and adjusting the relationship between vegetative growth and reproductive growth. This requires more meticulous management, and the prevention of pests and diseases cannot be relaxed at the moment. When lowering the greenhouse temperature to regulate the growth rate of crops, we must fully ensure that the temperature of the soil can not be too low, so as to avoid poor root development, resulting in sudden disease.
Management instance
Cucumber grafting anti-wheat grey mold mildew spot early prevention. Cucumber grafting technology has been widely promoted, generally with black-skinned pumpkin as the rootstock. Grafting effectively overcomes the continuous cropping of cucumbers to prevent the occurrence of wilt disease. The problem to be noted after grafting is that, after grafting, the root of the cucumber must be removed, otherwise the root of the black-skinned squash will grow poorly, the interface will not heal well, and the cucumber root will be infected with wilt.
Cucumber gray mold, downy mildew and bacterial keratoses are the most noteworthy issues in cucumber production before the Spring Festival. These diseases have a rapid development and a strong ability to damage. Among them, downy mildew and bacterial leaf spot damage cucumber leaves, while gray molds harm flowers, young fruits, stems and leaves, and it is most common to harm flowers and young fruit. Several diseases have similarities due to their occurrence laws and can be controlled at the same time.
Cucumber is a typical representative of the cucurbit family of vegetables. Other cucurbitaceous vegetables such as zucchini, watermelon, melon, and bitter gourd mostly need to be grafted and cultivated to resist the occurrence of wilt disease. In addition to wilt disease, powdery mildew in the melons is a serious hazard. Keeping the greenhouse airy and light-transmitting and not applying partial nitrogen fertilizer can reduce the incidence of disease. When the disease occurs, it is necessary to spray medicine as early as possible at the beginning of the disease to achieve a multiplier effect.
Tomato physiological diseases should pay attention to the finer management of pepper. Compared with cucumbers, tomato has a well-developed root system and strong absorptive capacity. The lifespan in greenhouses can be as long as 2-3 years and the yield is extremely high. In terms of management, tomatoes are less sensitive to water and fertilizers than cucumbers, and are more extensively cultivated and managed than cucumbers. The diseases of tomato during this period mainly include early and late blight and gray mold. Its temperature and humidity control is similar to that of cucumber, except that the upper temperature limit of tomato is lower than that of cucumber. When the air outlet is closed in the morning, the temperature inside the greenhouse reaches 30. -32 °C can be.
In addition to several common diseases, the physiological diseases and virus diseases of tomatoes have become more and more serious in recent years, such as umbilical rot, tendon rot, malformed fruit, and leaf rolling disease. Most of the causes of these diseases are caused by the combined effects of various adverse conditions. Low temperatures, high temperatures, low light, high night temperatures, potassium deficiency, and excessive nitrogen fertilizers can all cause these diseases. To prevent the occurrence of such diseases, comprehensive measures must be taken. On the basis of reasonable regulation of temperature and humidity, reasonable fertilization and top-dressing, appropriate thinning, improvement of lighting conditions in the shed (pruning fork), and selection of an appropriate concentration of phytohormone drugs are required. Liquid and so on.
Other solanaceous crops such as pepper and eggplant are also highly effective species for winter cultivation. Peppers are controlled at 28-30°C and eggplants are at 26-28°C. The roots of chilli peppers are shallow, not tolerant to drought, and not resistant to cockroaches. They are afraid of high temperatures and low temperatures. Therefore, they need to be more careful than tomato and eggplant in cultivation and management. On the basis of correct control of temperature and humidity, regular spraying of protective fungicides can limit the occurrence of various types of diseases; prevention and treatment of viral diseases should simultaneously treat aphids and try to avoid damage caused by agricultural operations.
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