Cryogenic illumination and windy greenhouse crops prevent three pests
Recently, heavy snow fell in Beijing, and the temperature plummeted. During the day, the daytime temperature was below 0 degrees Celsius and the night temperature dropped to minus 13 degrees Celsius. Sustained low temperatures cause serious frost damage in crop production. In response to sudden and severe weather, farmers should adopt measures to prevent freezing and injurious crops in order to mitigate the loss caused by disasters to agricultural production.
Disease
According to the statistics of the Climate Center of Beijing Meteorological Administration, from November 5 to November 22, Beijing has experienced cloudy days for 18 consecutive days. It is the longest history of consecutive days, and there is a serious shortage of lighting resources. Affected by this, the temperature in the greenhouses of the city’s facilities will continue to be low, the humidity is high, and the light is weak. Some greenhouses have diseases such as downy mildew of cucumber and leafy vegetables, late blight of tomato, and grey mold of solanaceous vegetables.
At present, the vegetables in this Municipality are worthwhile to postpone the growth of late autumn vegetables and winter and spring vegetables, and they will continue to be subjected to low temperatures after experiencing adverse weather such as long cloudy days, rain, snow, and haze in mid-November. Due to the cumulative effect of the lack of illumination, the growth of vegetables is generally weak. The continuing rain and snow weather in early November will further aggravate the “light and hunger†of the vegetables in the facility, and the strong wind and cold weather after the rain and snow will make the facilities more “frostedâ€. The improper cultivation and management of the greenhouse will easily result in The occurrence and spread of low temperature and high humidity diseases. It is estimated that from mid-late November to early December, the disease of vegetables in the city’s facilities is generally moderate to heavy. Diseases such as cucumber and other melons such as downy mildew, tomato late blight, solanaceous vegetable gray mold, and mushroom yellow leaf spot are Partially mismanaged canals have serious possibilities.
Cucumber downy mildew
â– Symptoms mainly harm the leaves. Seedlings can reach the adult stage, and the period of the melon period is the most serious. The leaves were infected, and light green spotted spots appeared on the leaves. After expansion, the spots became light brown. The veins were limited to polygonal and yellow-brown. The disease expanded and merged into irregular large spots, causing the leaves to be brown and dry. When the humidity is high, gray and black moldy layers are visible on the back of the lesions; later lesions are broken, leaf margins are curled, and diseased leaves develop from bottom to top. When severe, the leaves of the whole plant die and the field is yellow.
Leafy mildew (for celery, for example)
â– Symptoms mainly damage the leaves. On the lower leaf surface, there are keratinous lesions with pale veins as the boundary, and the white flora is formed on the back. It gradually spreads to the surrounding area, resulting in the fusion of flora and leaves. The foliage is covered with a layer of white mold. . In severe cases, the leaves turn yellow and dry.
Tomato late blight
â– Symptoms mainly harm the leaves, fruits, and stems. The leaves often have irregular dark-green water-spotted lesions from the tips or edges of the leaves. They then expand into dark-green spots with indistinct edges. The sick and healthy borders are white when wet. Mold layer. The main stem mostly occurs at the base of the stem, with dark brown spots appearing first. Then it expands around the stem. The stem turns black and eventually the whole plant withers. Branches began at the birthplace, the affected area was dark brown, and the upper branches died. The onset of green fruit often produces large spots with inconspicuous boundaries on one side. The diseased part was initially oil-immersed and gradually turned brownish or brownish. It was slightly sunken and outwardly irregularly spread like a moire. A white mold layer can be formed on the edges of the lesion when wet.
â– Prevention and control measures against downy mildew can choose 22% urea chlorothalonil, 20% bacillus chlorothalonil, 40% chlorothalonil, 10% chlorothalonil, 47% enoyl Azopyrazole suspension agent, 60% oxazolidone water dispersible granules and other agents. For the prevention of damping-off disease, it is possible to use 10% Diosfoam, WP, 20% copper acetate wettable powder, 300 million CFU/HAZ, and other agents.
For the prevention and treatment of late blight, 0.5% amino oligosaccharine, 3% polymyxin wettable powder, 250 g/l azoxystrobin suspension, and 72% urea manganese zinc wettable powder can be used.
Botrytis cinerea
â– Symptoms mainly harm fruits, leaves and stems can also be affected, mainly in the seedling stage and flowering period. When the seedlings develop, the tips of the leaves turn yellow, and the lesions show a "V" shape. Afterwards, they spread to the young stems until they contract and become thin. The diseased part is collapsed and died. The pathogenic bacteria are most likely to infect the petals, and the incidence of the fruit often starts from the remaining petals, receptacles and stigmas, and then spreads to the fruits and stalks, and the damaged fruits are gray and soft. The fruit was damaged firstly in the pits of the pedestal. The lesions appeared watery and grayish-white lesions. After the expansion, the lesions were sunken and the brown soft rot was found. When the damp was wet, the diseased part had a gray moldy layer, which was irregularly arranged in a roulette pattern and generally did not fall off. The most obvious feature of gray mold is that the diseased parts produce a brownish brown mold layer.
â– Prevention and control measures: 15% Pythium chlorothalonil smoke, 20% Pythium chlorothalonil, 15% Procymidone, 50% Boscalidamide, 40% Dimethoprim Fungal suspension agent, 65% acetylthiazide Wei wettable powder and other agents.
Pleurotus ostreatus bacterial yellow spot
â– Symptoms Pleurotus ostreatus Bacterial yellow spot disease occurs early on the surface of the surface of the cap yellow spots, when the humidity is high, the site of the disease has a sticky wet sensation, penetrates into the tissues, causing rot of the mushroom body, accompanied by thick secretions, dissemination Odorous odor, affect the appearance of oyster mushrooms, and loss of food value.
â– Prevention and control measures pay close attention to weather changes, strengthen field management, and reasonably spray water and ventilation to prevent stagnation and stagnation of greenhouses. Conditional heating may be appropriate to reduce the occurrence of low-temperature freezing damage and avoid excessive temperature difference between day and night. Condensation occurs on the surface of the cap.
Strengthen the inspection, early detection and removal of mushrooms, and pay attention to the environment clean so as to delay the spread of the disease and mitigate the damage.
City Plant Protection Station, Mu Changqing, Ying Ying, Zhang Zhi
Freezing damage
Freezing damage threatens agricultural production
When the temperature suddenly drops below zero degrees Celsius or when the low temperature lasts for several days, the plant loses its physiological activity due to ice in the intercellular space, and the damage to the crop is freezing injury. Food, vegetables and fruit trees have a certain range of temperature requirements. If they exceed the temperature limit to which they can tolerate, their physiological activities will be hampered, and the emergence will be slow, the growth will be weak, and the blight disease will be severe; the planting period will be postponed, and the planting period will be delayed. The period is prolonged; the growth potential is weak, and flowering, fruit setting, and time to market are all delayed; in severe cases, the plants are directly frozen to death. Therefore, freezing damage poses a serious threat to agriculture and can cause serious economic losses.
Frost damage characteristics of different crops
â– Wheat
There are two main types of cold damage during the winter and the spring cold in the spring. During the winter, the cold injury was divided into three types: dead leaf, dead borer and dead seedling due to the severity of the damage. The first type is severe freezing injury, that is, the stem and the main stem and the Oita are frozen to death, the heart is dry, generally occurs in the jointing wheat field; the second type is the general freeze injury, the symptoms are yellow and white leaves dry, but the main stem and the big stem are not frozen dead. The first type of frost damage will affect the yield, and the second type of frost damage will have little effect on the output. Cold injury caused by the spring cold in spring, light on the leaves have frozen horizontal stripes or dry tip dry leaves, heavy occurrence of the lack of grain, the number of grains per ear.
â– Vegetables
Every winter, cold weather, greenhouse insulation facilities are not perfect, the air volume is too large and other factors, resulting in greenhouse damage caused by vegetables. The light leaves turned white in thin paper, and the heavy water was spread on the ground. The frozen leaves eventually die and die.
Leaf damage is mild frost damage. Cotyledon stage suffers from chlorosis on the edge of cotyledon, with “white borderâ€, and the true leaf growth is not affected after the temperature returns to normal. Short-term low-temperature or cold-wind infestation after planting, and some leaf margins of plants are affected. It will appear dark green and gradually dry.
Roots suffered from the loss of root growth, no new roots could occur, and some old roots were yellow and gradually died. A sudden increase in temperature causes plants to wilt or slow down. Plants with severe damage are difficult to recover.
The damage at the growing point is a relatively serious frost damage, often causing the top buds to freeze, not to make new leaves, and if the weather does not recover after warmer weather, it is necessary to make up the seedlings.
Flower and fruit damage, the cold weather in the flowering period of vegetables will affect the effect of pollination and fertilization, resulting in a large number of fallen fruit or fruit.
â– Fruit trees
Frozen parts are roots, branches, cortex, annual branches, flower buds and so on. The frost damage in the root system was dominated by deep winter seasons, with late spring or irregular shoots and dry-out of the whole spring. Branches freeze and cause damage to the trunk, the bark is separated from the xylem, and in severe cases the bark rolls out.
Branches are frost-damaged and late-ripe shoots are most vulnerable to freezing injury.
Flower buds freeze damage, the internal browning, severe flower buds shrink and die.
Freezing damage to soil fertilizer measures
â– Wheat
Before the winter, the appropriate winter irrigation and seedling safety wintering, strong seedling watering temperature is 3 °C -5 °C, the amount of winter irrigation can not be too large, to the end of the day is appropriate. Do not avoid the formation of ice in the area where the water is cold, so that the plants are frozen.
Fertilization in early spring of wheat can make up for winter soil fertility, increase nutrient accumulation, promote the growth of young wheat seedlings, and resist or reduce early spring freezing injury. Especially in the winter season when the temperature is high, the wheat seedlings continue to grow, and the soil consumption is high, fertilization in early spring is particularly important.
â– Vegetables
During spraying, potassium dihydrogen phosphate and trace element foliar fertilizers were sprayed to improve the cold resistance and antifreeze ability of the seedlings. In the sunny afternoon noon, foliar spray suitable amount of quick-acting fertilizer, available 2% urea solution and 0.2% potassium dihydrogen phosphate solution foliar Spray or amino acid liquid fertilizer 1000 times.
â– Fruit trees
Filling the frozen water before freezing can improve the cold resistance of the fruit trees, maintain the balance of the ground temperature during the winter, and simultaneously play the role of winter water spring and prevent the spring drought.
0.5% calcium chloride was sprayed in the initial stage of germination to delay the flowering period by 4-5 days. Before germination and flowering of fruit trees, 0.3%-0.4% potassium dihydrogen phosphate and 0.3%-0.5% of urea solution were sprayed 1-2 times. The cold resistance of fruit trees during the flowering period; the management of fertilizers and waters in the later stage of growth, the application of phosphorus and potash fertilizers, and warm and hot fertilizers; the application of organic fertilizers in the fall, and the spraying of foliar fertilizers after harvesting.
How to remedy frozen injury
â– Wheat
Do not destroy the wheat as soon as possible after freezing injury, and actively take measures. The self-regulatory and compensatory ability of wheat is strong, and the frozen main stem and most stolons can sprout small tillers. Timely watering, topdressing available nitrogen fertilizer, Mushi urea about 10 kg, can promote the early delivery of wheat, small smash catch up, increase the rate of tilling spikes, reduce the loss of frost damage, jointing period per acre and then topdressing urea 7.5-10 Kg; spray 1-2 times humic acid foliar fertilizer can promote the recovery of wheat as soon as possible.
â– Vegetables
After most of the frozen tissue is revived, the quick-acting fertilizer should be applied in a timely manner to allow the plants to quickly absorb, increase the cell fluid concentration, and restore the growth ability. It is better to use ammonium sulfate. Can use 0.3% -0.5% of urea solution and 0.2% of potassium dihydrogen phosphate solution foliar spray; also available in the afternoon 2-3, foliar spray sweet and vinegar solution (sprayer add brown sugar 100 grams, vinegar 50 Grams, urea 50 grams, potassium dihydrogen phosphate 75 grams, can be fully stirred evenly). For irrecoverable frozen leaves and branches, cut them in time to avoid mildew induced by frozen tissue.
Watering in time, the best use of groundwater, should not use the ground water, can inhibit the temperature drop, stable surface and the air temperature inside the shed, the amount of water to reach the plough layer is appropriate, should not flood irrigation. Artificial water spray was carried out to increase the air humidity in the shed, stabilize the temperature of the shed, and suppress the evaporation of water from the frozen tissue to promote water absorption.
â– Fruit trees
Immediately after the occurrence of cold injury, a shallow ditch is opened in the tree tray, and sufficient water is poured to cover the soil.
Early application of spring fertilizer, mainly available nitrogen, preferably thin human feces; the second spring fertilizer can add appropriate amount of calcium, available 0.3% -0.5% urea plus 1% -5% of superphosphate and 4% of the leaching of ash The leaching solution is used for top-dressing outside the roots, stabilizing the fruit fertilizer in advance, and increasing phosphorus and potassium fertilizers. When the frost damage is in the budding stage, the chelating fertilizer containing high boron, high phosphorus, and high zinc is applied; when the freezing damage is in full bloom, the chelating fertilizer containing high zinc, high nitrogen, and high phosphorus is applied.
Municipal soil fertilizer station Wen Fangfang
Cold damage
In winter, when the minimum temperature in the facility is below 8°C, greenhouse vegetables are prone to cold damage. Hope to help the majority of planters take timely measures to reduce losses.
Common symptoms
â– Dead spots appear in leaf spots and leaf dead leaves. They are of different sizes. They start from the tips of leaves or parts that are far away from the veins, and are light in color; sometimes, leaves appear dry later in the chilling injury, and they appear as dead leaves.
â– The leaf yellowing plants grow slowly, and the leaf color gradually becomes lighter and yellowish. This is mainly due to the low temperature and low illumination caused by the cloudy days, and the photosynthesis of the plants is weakened, resulting in lack of nutrition.
â– The wilting of the whole plant generally shows that the plant slowly turns yellow and then gradually wilts from top to bottom.
â– Flower topping is more common in cucumbers and other melons. It shows that the growing point of the plant gathers a large number of female flowers or small melons, and the plants stop growing.
â– Floral and fruit deformities are more likely to appear on tomatoes. The number of sepals in flowers is increased, and the fruits are different from normal fruits. In addition to the fact that the fruits are not easy to be colored, the color is shallow, and the length of the heads is smaller, the phenomenon of fruit cracking and long fruit is also seen.
In addition, the continuous low temperature can also cause the whole plant nutrient deficiency, decreased resistance, resulting in falling, fruit drop, causing bad sowing season, induced gray mold and damping-off diseases and other diseases.
Control measures
â– Improve the temperature of the greenhouse to increase the coverage around the greenhouse, add a layer of plastic film on the rake; try to cover the double plastic film; clean the shed film in time to increase the light transmittance; timely repair damaged shed film in the shed Doors are hung with cotton curtains to close the gaps of the wall joints. The film lines should be compacted and compacted to improve the tightness of the booth. Silver reflective curtains are suspended in the upper half of the north side of the booth to facilitate the interior of the booth and the walls. Storage temperature.
â– Raise the ground temperature Dig out the cold-proof ditch on the outside of the south side of the greenhouse, fill in heat-insulating materials such as straw and wheat straw, cover the ground with a layer of mulch on high ridges, and add a small shed to cultivate the flat ridge to increase the ground temperature; Fertilizer and plant ash can improve soil structure, increase soil heat capacity, strengthen soil heat absorption, and promote ground temperature increase; in the shed, crop lines can cover the mulch between the rows, and spread hay to reduce moisture evaporation and heat loss.
â– Warming and heating There is a greenhouse for heating and light-supplying equipment to increase the heating and fill time. Without conditions, it is possible to increase the temperature inside the shed by using a small furnace.
â– Low-temperature training Use variable-temperature management when growing fruit and vegetables. Through cold-resistant exercises, strengthen the cold resistance after planting.
â– Addition of antifreeze substances. Available foliar fertilizers, potassium dihydrogen phosphate, and brassinolide can be used for foliar spraying of victim crops, which can alleviate the symptoms of cold damage and enhance crop cold resistance.
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