During the high temperature, drought and rainy periods in summer, various crops, especially vegetables, are subject to various natural weather hazards, and even serious losses may occur. Therefore, it is very important to do summer management work.
First, summer defense vegetables "three evils"
1, anti-high temperature hazard
The optimum growth temperature for most thermophilic vegetables such as tomato, eggplant, pepper, cucumber, etc. is 25-30 °C; and the optimal growth temperature of Xiliang vegetables such as celery, cabbage, green beans, etc. is 20-25 °C, so summer The high temperature (temperature above 30 °C) dry weather is extremely detrimental to the growth and yield of vegetables, which is the root cause of the “autumn†of vegetable supply on the market. For example, when the solanaceous vegetables encounter temperatures above 30 °C during flowering, not only will the flowers fall, but the longer the duration, the lower the fruit setting rate; when the beans are at temperatures above 25 °C, The pollination rate will be greatly reduced; when the cucumber is at a temperature above 32 °C, the net assimilation rate will be significantly reduced, resulting in reduced production or even production. When there is a long period of high temperature, even heat-resistant vegetables such as melon and cowpea sometimes have poor growth. Only the plants with absolute heat resistance such as water spinach and pumpkin can grow normally. Moreover, long-term high temperature and drought will also cause diseases such as sunburn, virus and blight.
2, drought prevention hazards
Drought refers to the phenomenon that the precipitation is abnormally low, causing the air to be excessively dry, the soil moisture is seriously deficient, and the surface runoff and groundwater volume are greatly reduced. Drought often becomes a serious natural disaster due to its long duration and wide range of spread. Drought makes water supply scarce. In addition to harming crop growth and causing crop yield reduction, it also endangers residents' lives and affects industrial production and other social and economic activities.
Drought can be divided into two aspects: soil drought and atmospheric drought. The main cause of soil drought is insufficient precipitation; the main manifestation of climate drought is also insufficient precipitation. Therefore, insufficient precipitation is the root cause of the drought problem. The climate causes of insufficient precipitation include: continuous wide downdraft, local submerged airflow, lack of air pressure disturbance, and lack of humid airflow.
The most direct hazard of drought is that the growth and development of vegetables are hindered, and the area is reduced and the quality is reduced. In addition, high temperature and dry weather conditions are conducive to the proliferation and harm of red spiders and locusts.
Summer and autumn are the seasons for most autumn vegetables. The high temperature and drought will affect the germination of seeds. After sowing, it will be affected by heavy rain. The seeds will be washed away to the bottom of the ditch or exposed to the soil surface, resulting in lack of seedlings.
3, anti-storm damage
Summer is not only prone to high temperature and drought, but also prone to violent storms. When the sudden storm is directly blown to the scaffolding of melon beans, it will rot the leaves and smash the vegetable seedlings, causing the melon bean crops to fall seriously and the vegetable production will be damaged. When the storm is accompanied by the river bed and the groundwater level rises, the low-leaf vegetable field will drown the vegetable seedlings by the accumulated water, which will cause the soil to wet and compact, reduce the soil permeability and affect the root growth. After the storm, the weather tends to be fine. Because various vegetables have just been devastated, water and fertilizer are lost, and the plant resistance is weak. It is easy to induce diseases such as blight and blight, and the rain will cause pests such as Noctuidae. And it is difficult to control, and finally leads to a decline in production.
After the emergence of seedlings in summer and autumn, the topsoil is exposed to heavy rain, the roots are exposed to the space, and the sun is exposed to the sun. The vegetable seedlings are wilting and dead; all kinds of vegetables and vegetable seedlings are damaged by heavy rain machinery, the growth potential is reduced, the yield is reduced, and the market is small, forming a dish. Low price and high phenomenon.
Second, the summer vegetables "three evils" defense measures
In view of the above-mentioned situation that vegetables are prone to occur in summer, corresponding measures should be taken in time according to different situations in production.
1. For fruits and vegetables (such as tomatoes, cucumbers, and peppers), attention should be paid to strengthening water and fertilizer management in the middle and late stages, promoting the flourishing of branches and leaves, to reduce the burning of fruits by sun exposure, and to improve the ability of plants to resist high temperature and drought.
2, shade cover cultivation. In the summer, the shade net and the insect net can be used for covering cultivation, which can prevent the direct radiation of the sun from burning vegetables. Generally, it can be cooled by 3~10 °C than the open field cultivation, so that the cool shade-tolerant vegetables can also be used in summer, and the seed emergence can be improved. Rate, the survival rate of transplanted seedlings, while reducing pests and diseases. Straw or straw can also be covered on the soil surface to reduce the emission of soil moisture. While applying sunshade coverage, rational application of plant growth regulators can effectively prevent fruit and vegetable crops such as tomatoes and eggplants from falling and falling.
3, high temperature and dry season, should try to choose heat-resistant, disease-resistant vegetable varieties for cultivation, such as melon, loofah, cowpea, spinach, white and so on.
4. Water management should be balanced. At high temperatures, care should be taken to keep the soil moist, water it at the right time, and cool down by evaporation. Conditional fields use sprinkler irrigation to better water, but care should be taken to avoid watering at high temperatures around noon to prevent physiological diseases such as cracking.
5. Implement deep ditch and sorghum farming. In the whole process of vegetable growth, the field ditches should be connected at the same time and drained and drained freely. When encountering rainy weather, it is necessary to ditch drainage or mechanical drainage in time. The plants that are flooded and blown down should wash away the sludge on the stems and leaves in time, and remove the yellow rotten leaves and straighten the plants. After the soil is slightly dry, it will be ploughed and soiled in time. In addition, deep cultivation of soil and application of organic fertilizer can improve soil physical properties, improve soil water seepage capacity, and have certain effects on reducing rain and wetness and drought.
6. After rain and fine weather, timely use low-toxic pesticides such as carbendazim, chlorothalonil and mancozeb to prevent and cure diseases. Pay attention to the expiration date and safety period of the medicine when using the medicine.
7. The high temperature and dry weather conditions are conducive to the reproduction and harm of red spiders. The main diseases of red spiders are beans, cucumbers and eggplants. Although the spider is small, it is very harmful. Therefore, it is necessary to observe in time, find out in time, and prevent it early.
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