Spring field management for winter wheat: remember these eight key points
Spring is the critical period that determines the number of spikes per mu, the number of grains per spike and grain weight in wheat. Strengthening spring field management according to seedling conditions is the key to achieving high wheat yields. In terms of management, the eight key points of “pressing, raking, clearing, topdressing, watering, controlling, preventing and protecting” should be implemented as priorities.
Pressing: namely pressing wheat in early spring. Pressing wheat in early spring can settle the soil, close soil cracks, and serve to lift moisture, preserve moisture, protect against cold, control excessive growth and prevent lodging, and promote early root development and early greening. The suitable period for pressing is generally 1 to 2 times from the period when the surface soil thaws and returns to slurry to the greening stage in ordinary wheat fields; in wheat fields with excessive growth, press 2 to 3 times from the greening stage to the stem elongation stage, which can inhibit aboveground growth and serve to control excessive growth, turn plants strong and prevent lodging; in wheat fields where seedbed preparation was rough at autumn sowing and there are many clods, timely pressing of the wheat field should be carried out after the soil thaws in early spring. Pressing should achieve “two earlies and three no-pressings”. That is, wheat fields with poor seedbed preparation quality should be pressed early, and wheat fields with poor moisture conditions should be pressed early to connect soil capillaries and lift moisture; do not press wheat in the early morning, do not press wheat when soil moisture is too high, and do not press wheat when plants are frozen, so as to avoid crushing wheat leaves and damaging soil structure.
Raking: namely hoeing, loosening soil and raking wheat. Hoeing and loosening the soil has the effect of raising temperature, preserving moisture, promoting weak plants to turn strong and controlling excessive growth to turn healthy, and promoting early root development and rapid growth of new tillers in wheat seedlings. Generally, before and after greening, first press and then hoe, loosen soil and rake wheat; in ordinary wheat fields the hoeing depth is 1 to 2 cm, and where there is a risk of lodging the hoeing depth is 3 cm.
Clearing: namely timely clearing of winter coverings. If measures such as covering with soil or manure were taken in winter to protect against cold, clear them in two operations at the greening stage together with raking wheat, to prevent manure and soil from affecting leaf photosynthesis.
Topdressing and watering: namely topdressing fertilizer and watering. Topdressing and watering should achieve the “five looks”, scientifically carrying out fertilizer and water inspection.
Spring fertilizer and water management should be carried out according to the specific conditions of soil moisture, seedling condition, period, weather and soil fertility.
For wheat fields where sowing was done by grabbing moisture before winter and the freezing water was applied too early, or where freezing water was not applied and drought is severe, when the temperature steadily passes above 3 degrees C in mid-March, choose a sunny day and carry out small-water fine irrigation from 10 a.m. to 4 p.m., strictly control the water amount, and do not flood irrigate; if there is a sharp temperature drop, stop irrigation immediately and wait until the temperature rises before irrigating, to prevent freezing injury.
For third-class wheat fields with poor moisture and a total stem number per mu of less than 450,000, give priority to promotion, irrigate the first fertilizer and water at the greening stage, and apply 5 to 8 kg of urea per mu with the irrigation; irrigate the second fertilizer and water at the jointing stage, and apply 10 to 15 kg of urea per mu with the irrigation. For second-class wheat fields with better moisture and a total stem number per mu between 450,000 and 600,000, irrigate the first fertilizer and water at the wheat stem elongation stage, and apply 10 to 15 kg of urea per mu together with irrigation. Among them, for wheat fields where seedlings are relatively weak and the population is insufficient, topdressing and watering may be carried out from the early stem elongation stage to the mid stem elongation stage; for wheat fields with a suitable population, the first topdressing and watering should be carried out at the late stem elongation stage.
For first-class wheat fields with good moisture and a total stem number per mu between 600,000 and 800,000, the first fertilizer and water may be postponed to the jointing stage, and 12 to 15 kg of urea per mu applied together with irrigation.
For vigorous seedlings with a total stem number per mu greater than 800,000 and a risk of lodging, cultivate and press before jointing to control excessive population growth. Generally, water and fertilize at the late jointing stage, applying 8 to 10 kg of urea per mu.
Controlling: namely chemical control to prevent lodging. Chemical control can effectively shorten the length of basal internodes and improve lodging resistance. For high-yield plots, or a small number of wheat fields that due to early sowing and excessive density reach more than 800,000 stems per mu before winter, or wheat fields with a tendency to excessive growth due to excessive fertilization, or plots where varieties have poor lodging resistance, at the stem elongation stage use 37.5 to 50 g of 10% Guoguang Aifeng wettable powder per mu, or 25 to 30 mL of 20% Zhuangfeng'an emulsifiable concentrate, diluted with 30 kg of water and sprayed evenly, strictly controlling the dosage, with no repeats, no omissions and no drift.
Preventing: namely integrated control of diseases, insects and weeds. Spring is a season with frequent diseases, insects and weeds in winter wheat, and timely control should be noted. The main wheat insect pests in spring are red spiders and red blossom midges, and the main diseases are root rot and take-all.
Wheat red spiders can be controlled by spraying with Puke aqueous solution or abamectin. For the first control of wheat red blossom midge, in the eastern Hebei region this is generally from April 20 to 30, using 2 to 3 kg of chlorpyrifos per mu mixed with 20 to 30 kg of fine moist soil, evenly broadcast in the wheat field; if moisture is insufficient, water should be applied; for the second control, at the wheat heading and flowering stage, use Kuaishaling and deltamethrin diluted with water for spraying, to control adult wheat red blossom midges and also control wheat aphids.
For root rot and take-all, root irrigation with 500 to 800 times dilution of 20% triadimefon can be used for control.
Wheat field weeds. At the wheat stem elongation stage, when weeds have 2 to 3 leaves, choose clear and windless weather for chemical weeding. During chemical weeding, strictly control the dosage to avoid phytotoxicity.
Protecting: namely timely protection against low-temperature freezing injury in spring. After wheat turns green, pay attention to listening to and watching weather forecasts and closely monitor weather changes. If a sharp temperature drop is forecast in the near future, before the cold wave arrives, spray plant growth regulators such as “Bihu” or Tianda-2116, Yunda 120, Lufeng 95 plus a 0.2% potassium dihydrogen phosphate solution. For “Bihu”, use 3 g per mu diluted with water for spraying, and irrigate within 2 to 3 days before the cold wave arrives, which can effectively prevent early spring freezing injury. If low-temperature freezing injury occurs, immediately take remedial measures, spray plant growth regulators such as “Bihu”, Tianda-2116 and Lufeng 95, apply about 10 kg of urea per mu, and carry out intertillage to preserve moisture, raise ground temperature, promote root development, increase the number of tillers, compensate for the loss of the main stem, repair damage and alleviate freezing injury.