Natural disasters of corn

drought

Typical symptoms: from sowing to emergence, surface soil moisture deficiency, seeds in dry soil, can not germinate and emerge, or cause lack of seedlings; sowing, seedling period is postponed; emergence of the land due to weak seedlings weak, small plants , Stunted growth, population growth is not neat. Treatment measures: Increase the use of organic fertilizer in drought-prone areas, improve soil recultivation, fertility and fertility, improve soil buffer capacity and drought resistance; adopt water storage and soil conservation cultivation techniques and establish “soil reservoirs”; select drought-resistant varieties; and cover with plastic film. Cultivation; Autumn covered with plastic or top mulching; Drought-resistant sowing: robbing sowing, water (water filtration) sowing, dry seed wet, deep sowing shallow cover, no tillage sowing, pay close attention to preparatory work, waiting for the rain to be broadcast .

After the drought: 1. Classification management: The emergence of more than 70% of plots, postponed Dingmiao, leaving two plants, protect the group; emergence of more than 50% of the land, as soon as possible germination sit water replanting or transplanting; lack of seedlings in 60% The above plots were replanted with early-mature corn, silage corn or other crops with short ripening periods. 2. Take measures to fully tap water sources and increase the effective irrigation area. 3. Strengthen the management of the field. The emerging plots should be cultivated as early as possible, shallow cultivator, and reduce soil evaporation. Lodging

Typical symptoms: Dust weather causes seedlings to be covered with dust and leaves. The wind disaster caused the seedlings to fall down and break; soil compaction, high humidity, and insect pests affect the development of the roots, resulting in small roots and shallow roots, and prone to root collapse. Seedlings during the seedling and jointing stages are lodged in the wind, and the plants are generally able to stand upright. Treatment measures: 1. Use resistant varieties. The soil is deep and loose. 2. In areas with heavy winds, pay attention to properly reduce planting density and plant corn in the wind direction; 3. The seedling stage lodging is often accompanied by more rain and damage, and the water is drained in time after the disaster. 4. Strengthen management, such as earthing, cultivating, and removing compaction, can also increase available nitrogen fertilizer to improve plant growth.

hail

Typical symptoms: direct damage to corn plants, frostbite plants; soil surface compaction, ground panel knots; stems and leaves infected after trauma. The degree of damage depends on the size and duration of the hail block. Treatment measures: Improve artificial anti-smashing facilities such as earthen cannons, anti-aircraft guns, and rockets to prevent and eliminate disasters in time. As soon as possible after the disaster, assess the impact on production. The main measures: 1. The ability to recover after the seedling period is strong, as long as the growth point is not destroyed, it can restore growth, and carefully destroy the species. 2. Timely cultivating loose soil, breaking compaction, increasing ground temperature, increasing soil permeability, and applying topdressing available nitrogen fertilizer (urea 5-10 kg per mu); spraying new leaf potassium dihydrogen phosphate 2-3 times after the new leaf grows. Promote new leaf growth. 3. Pick out the broken leaves that are wound together so that the new leaves can grow smoothly. 4. Be alert to the occurrence of diseases.

Cold damage

Typical symptoms: Maize sowing seedling stage and seedling stage vulnerable to low temperature damage. Delayed emergence of cold injury, susceptible to smut and other diseases, and cause plant growth retardation, reduce the individual quality of seedlings. Metabolic effects decrease, cell membrane permeability decreases, and protein degradation. The browning and wilting of the mesocotyl and coleoptile, the appearance of water-stained leaves and incomplete development of the leaves, and even the impaired growth of the seedlings do not survive, and the chilling injury symptoms can continue until the growth period is restored. Treatment measures: 1. Do a good variety division, use cold-resistant varieties. 2. Seed treatment. With the concentration of 0.02% -0.05% copper sulfate, zinc chloride, ammonium molybdate solution soaking, can increase the germination of corn seed at low temperatures, reduce chilling injury. 3. Suitable sowing. According to the minimum temperature of germination of maize seeds, combined with local meteorological conditions, arrange appropriate sowing time, to avoid the threat of cold damage.

Freezing damage

Typical symptoms: The nature of frost-damaging plants is low-temperature freezing injury, but the freezing damage to plants is not due to the direct effect of low temperature, but mainly due to the freezing or freezing of plants in plant tissues. The northern dry-farming corn area is vulnerable to cold spells from April to May. Treatment measures: 1. Grasp the law of occurrence of local low-temperature frost, select suitable varieties for the growth period, so that corn sown in the "warm head cold end." 2. Choose crops or varieties with strong cold-resistance and adopt cultivation techniques that can improve the cold-resistance of crops. 3. After the occurrence of frost, timely investigation of victimization and establishment of countermeasures should not be easily destroyed. Observe carefully whether the main stem growth cone freezes to death. If only the upper leaves are damaged, the heart leaf is basically unaffected. The field management can be strengthened, timely cultivating loose soil, raising the ground temperature, chasing quick-applied fertilizer, accelerating corn growth, and promoting new growth. Leaves grow. For fields with particularly severe freezing injury, all fields that cause corn deaths should be promptly replanted with early-mature corn or other crops. Stains

Typical Symptoms: Maize is particularly afraid of lice during sprouting and seedling stages. Sprouts sprouted at the 3rd leaf stage, inhibiting root growth, leaf wilting, yellowing, slow growth and dry weight reduction, and even large areas of seedling death. Low-lying terrain, heavy soil, and frequent rainfall are prone to occur. Treatment measures: Seedlings infestation often occur in the seedling stage, pay attention to supporting irrigation and drainage ditches; selection of flood-resistance varieties; adjustment of sowing date, making the sensitive phase of the most fearful floods as early as possible before the start of the rainy season; smoothing low-lying land; using ridge cultivation and other appropriate farming methods .

After damage occurs, damages should be promptly assessed. Main measures: 1. Drain the mud on the leaves in a timely manner. 2. Shallow cultivator, planer, ventilation and scab. 3. Timely application of available nitrogen fertilizers, such as ammonium sulfate, ammonium bicarbonate, supplement soil nutrient loss, restore root growth, and promote weak to strong. 4. When more than 60% of dead seedlings are replanted or changed to other crops. high temperature

Symptoms: The young leaves of high temperature at the seedling stage start to dry out from the tip of the leaf, resulting in the death of half leaves or even the entire leaves; the high temperature causes the chloroplast structure of the leaves to be destroyed, the photosynthesis is weakened, the respiration is enhanced, the consumption is increased, and the dry matter accumulation is decreased; the plant growth The weaker, the lower physiological activity of the roots, susceptible to pathogen infection during the seedling stage. Treatment measures: 1. High-temperature areas, pay attention to breeding and promotion of heat-tolerant varieties; adjust sowing date so that the flowering pollination season avoids high-temperature weather; appropriately reduce the density, wide and narrow row planting, and cultivate robust plants. 2. Sprinkle irrigation water in proper period to change the small climate of farmland.

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