Shanxi Rural Agriculture Department Guides Late-Stage Field Management of Winter Wheat in 2020
Grain Rain has passed, and winter wheat has successively entered the heading and flowering stage from south to north. This stage is the key period for wheat yield formation. So, how should the late-stage field management of winter wheat be carried out in 2020? The Shanxi Rural Agriculture Department has issued guidance opinions!
Recently, news came from the Shanxi Provincial Department of Agriculture and Rural Affairs that, in order to ensure a bumper summer grain harvest this year, the office of the provincial Department of Agriculture and Rural Affairs recently issued the "Opinions on Late-Stage Field Management of Winter Wheat in 2020" to guide localities in carrying out winter wheat field management.
Affected by the warm winter, the growth period of winter wheat in Shanxi Province has generally advanced, and the current seedling condition and growth are generally good, but the pest and disease situation is severe and complex. Therefore, all localities should attach great importance to it, earnestly implement the Ministry of Agriculture and Rural Affairs“100-day campaign to win a bumper summer grain harvest” plan and the National Agricultural Technology Extension Service Center“three major agricultural technology actions” plan, always pay attention to weather changes and pest occurrence trends, base themselves on disaster prevention and mitigation, and focus on tasks such as “strengthening water and fertilizer regulation, strictly preventing low-temperature chilling injury and lodging from strong winds, strengthening pest, disease, and weed control, preventing the harm of dry hot winds, and doing a good job in late-stage ‘one spray, three preventions’,” strengthen field management, and strive for a bumper wheat harvest.
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Opinions on Late-Stage Field Management of Winter Wheat in 2020
At present, winter wheat in Shanxi Province has successively entered the heading and flowering stage from south to north. According to recent surveys, the growth period of wheat in Shanxi Province this year is generally 7-10 days earlier. Due to sufficient winter and spring rainfall and higher temperatures, the late-sown southern irrigated wheat fields caused by frequent rainfall during the sowing period have notably caught up and improved, and dryland wheat has grown well because there was no obvious drought. Some dryland winter wheat fields that grew excessively before winter had that excessive growth momentum effectively controlled due to relatively low rainfall in March and multiple temperature drops from the end of March to mid-April. The current seedling condition is one of the better years in recent years, but there are still some risk factors in the later period. First, spring pests and diseases are occurring relatively severely, and the situation is severe and complex. In particular, stripe rust occurs early and causes severe damage in counties (cities) along the Yellow River. Plant protection experts predict that major pests and diseases in the middle and late stages of winter wheat in Shanxi Province will be more severe than last year and normal years, and Fusarium head blight will occur at a moderate level. Second, two frost events occurred consecutively from the end of March to mid-April. Current surveys show no obvious symptoms of frost damage, but the delayed effects of frost damage cannot be ignored. In the later period, natural disasters such as low-temperature chilling injury, dry hot winds, strong winds, and hail still require great attention. Third, there is still a certain proportion of weak late-sown seedlings and excessively growing seedlings, and field management still requires great attention.
In view of the current relatively good wheat seedling condition, but the severe pest and disease damage situation and the uncertain current state of meteorological disasters, the guiding ideology for late-stage field management of winter wheat this year is to base efforts on disaster prevention and mitigation, aim to preserve grain number and increase grain weight, take prevention of pest, disease, and weed damage, prevention of low-temperature chilling injury, prevention of dry hot winds, prevention of lodging, and prevention of premature senescence as the focus of field management, reasonably regulate water and fertilizer, timely prevent and control pests, diseases, and weeds, manage scientifically, and strive for a good wheat harvest this year.
1. Strengthen water and fertilizer regulation
In the late stage of wheat growth and development, water supplementation and fertilizer supplementation to prevent premature senescence should be taken as the focus of water and fertilizer management, with classified management, to promote large spikes, more grains, and heavy grains for a high yield.
(1) Supplement water according to soil moisture to prevent drought. From heading to the middle filling stage, wheat should be watered well with heading and flowering water and filling water according to soil moisture, to promote more grains and heavy grains. From heading to the grain formation stage, if soil moisture is insufficient, it often leads to grain degeneration and shrinkage, reducing the number of grains per spike and grain weight. Therefore, it is necessary to timely and sufficiently irrigate with heading and flowering water to meet the water demand for the synthesis and transport of photosynthetic products and the rapid expansion of grains. After entering the filling stage, maintaining suitable soil moisture supply is an important measure to extend the photosynthetic functional period of leaves, prevent premature senescence, and increase grain weight. Therefore, when the relative soil water content is below 60%, areas with irrigation conditions should timely irrigate well with filling water. It should be noted that unreasonable irrigation during the filling stage often leads to delayed maturity and lodging. Irrigation with filling water should follow four principles: first, irrigate less but frequently, and the amount of water each time should not be too large; second, strictly prohibit irrigation in windy and rainy weather; third, stop irrigation half a month before maturity; fourth, strictly control irrigation for wheat fields with excessive nitrogen fertilizer application.
(2) Spray fertilizer on leaves to prevent premature senescence. The period from heading to filling is the most important period for wheat yield formation, and also the key period for preventing premature senescence and increasing grain weight. Spraying potassium dihydrogen phosphate on the leaves 1 to 2 times from wheat heading to filling can make up for the insufficient absorption of nutrients by the root system, effectively increase phosphorus and potassium in the plant, enhance wheat stress resistance, extend the leaf functional period, improve wheat physiological activity, accelerate the filling rate, promote good yellowing and early maturity of wheat, and prevent and reduce the harm of dry hot winds and green wilt, increase the number of grains per spike, stabilize the 1000-grain weight, thereby increasing yield and improving quality. Therefore, regardless of irrigated or dryland fields, potassium dihydrogen phosphate can be sprayed from heading to the middle filling stage, with a general dosage of 200 grams per mu each time, diluted with 40-50 kg of water and sprayed on the leaves. For strong-gluten wheat, fertilizer-deficient yellowing wheat fields, frost-damaged wheat fields, and hail-damaged wheat fields, an appropriate amount of urea can be mixed and sprayed together, using 1 kg of urea and 100 grams of potassium dihydrogen phosphate per mu, diluted with 40-50 kg of water, sprayed on the leaves 2-3 times, with an interval of about 10 days.
2. Strictly prevent low-temperature chilling injury and lodging from strong winds
From the end of April to the beginning of May, low-temperature chilling injury occurs from time to time in Shanxi Province. If the minimum temperature is lower than 5-6°C, wheat will suffer damage. Therefore, close attention should be paid to weather forecasts, and before low temperatures arrive, measures such as irrigation, spraying frost prevention agents, or using intelligent smoke generators to spray smoke should be taken to prevent and reduce the occurrence of low-temperature chilling (freezing) injury. Once it occurs, timely irrigation or foliar spraying of potassium dihydrogen phosphate, brassinolide, and other foliar fertilizers or plant growth regulators should be carried out to promote restorative growth.
When encountering strong wind weather, field irrigation should be stopped immediately. According to weather forecasts, before storms, measures such as digging trenches for drainage can be taken to reduce the risk of root lodging and stem lodging caused by excessive water content in soil and plants. If wheat lodges in the later stage, manual support is strictly prohibited to prevent greater damage. After wheat lodging, its stems generally grow upward from the most vigorous meristematic tissue, restore heads and some stems turning upright, and photosynthesis and transport functions are partially restored. After lodging, wheat fields can be sprayed with potassium dihydrogen phosphate on the leaves to enhance stress resistance. At the same time, attention should be paid to preventing the spread of diseases such as rust and powdery mildew in lodged wheat fields. Foliar fertilizer and fungicides can be mixed for foliar spraying to achieve the purpose of promoting growth and preventing and controlling diseases.
3. Strengthen pest, disease, and weed control
From the booting to filling stage of wheat, as temperatures rise, the occurrence of various pests and diseases such as aphids, wheat blossom midges, powdery mildew, rust, and Fusarium head blight will show an upward trend. This year, affected by the warm winter and high temperature and humidity, pests and diseases occur early and cause severe damage. Therefore, all localities should strengthen monitoring and take corresponding control measures for different pests, diseases, and weeds.
Wheat stripe rust is a relatively severe disease, and in recent years it has occurred locally in the southern wheat region of Shanxi Province. This year, stripe rust spread rapidly in winter propagation areas, and the pathogen source is unusually abundant. With the rise in temperature and the introduction of pathogen sources from other places, counties (cities) along the Yellow River in Shanxi Province first observed the disease as early as March 20, one month earlier than usual. For stripe rust, the prevention and control strategy of “scouting with medicine and protecting the surface by treating spots” should be fully implemented, and preventive measures of “when one spot is found, control one area” should be adopted to timely control the center of infection. When the average diseased leaf rate in the field reaches 0.5%-1%, large-scale emergency control should be organized, and full coverage control should be achieved in similar areas. Agents can be selected from triadimefon, diniconazole, tebuconazole, epoxiconazole, hexaconazole, propiconazole, kresoxim-methyl, etc.
In recent years, wheat Fusarium head blight in Shanxi Province has shown a worsening trend. Attention should always be paid to weather changes. For areas where Fusarium head blight may occur (wheat areas with highly susceptible varieties), if the weather forecast predicts more than 2 consecutive days of overcast and rainy weather during the wheat flowering period, the first application time should be advanced to the heading stage. Agents can be selected from phenamacril, prochloraz, tebuconazole, thiram, thiophanate-methyl, Bacillus subtilis, etc. Sufficient dosage should be used. If rain occurs within 3-6 hours after application, timely supplementary treatment should be carried out after the rain.
Powdery mildew and leaf rust are common wheat diseases in Shanxi Province. At the early stage of the disease, when the diseased leaf rate of powdery mildew in the field reaches 10% or the diseased leaf rate of leaf rust reaches 5%, timely organize prevention and control. Agents can be selected from triadimefon, diniconazole, pyraclostrobin, propiconazole, etc.
Wheat blossom midge mainly occurs in old irrigated areas. In key occurrence areas of wheat blossom midge, before wheat heading, phoxim granules can be made into poisonous soil, evenly spread on the ground surface, and then watered for control. After wheat heading and before flowering, phoxim, beta-cyhalothrin, lambda-cyhalothrin·imidacloprid, and other agents can be selected for spray control.
Wheat ear aphids are relatively common in Shanxi Province. When the number of wheat ear aphids reaches 800 per 100 ears, and the beneficial-to-pest ratio (natural enemies: aphids) is lower than 1:150, agents such as pymetrozine, acetamiprid, imidacloprid, pirimicarb, matrine, and Verticillium lecanii can be selected for spray control. In areas with conditions, biological control by releasing aphidius wasps and ladybugs is encouraged. In mixed occurrence areas of multiple pests and diseases, suitable fungicides and insecticides can be scientifically mixed and applied comprehensively.
For wheat fields with relatively severe weed damage in the later period, manual pulling should be carried out before weeds set seed, to reduce the amount of grass seed left in the field and prevent spread into disaster. This is because grass seeds often mature earlier than wheat and have a high reproduction coefficient, especially grass family weeds, which cause greater damage. At the same time, attention should be paid to removing weeds at field edges to prevent grass seeds from being brought into the field through irrigation and cultivation.
4. Prevent the harm of dry hot winds
From wheat filling to maturity, Shanxi Province is often harmed by dry hot winds, causing wheat to mature early or green wilt, and grain weight to drop severely. Therefore, in areas where dry hot winds frequently occur, active preventive measures can be taken. First, timely irrigate well with filling water. Generally, irrigation during the milk-ripe to dough-ripe stage and before the period when dry hot winds frequently occur in normal years can effectively reduce the microclimate temperature of wheat fields, increase humidity, reduce plant transpiration water consumption intensity, and effectively slow down the damage. Second, spray 0.2-0.4% potassium dihydrogen phosphate solution 2-3 times from wheat booting to filling stage to increase phosphorus and potassium content in plants and improve wheat stress resistance. Third, from wheat booting to filling stage, 300 grams of edible vinegar or 50 grams of acetic acid per mu can be added to 40-50 kg of water and sprayed on the leaves twice to enhance wheat resistance to dry hot winds.
5. Do a good job in late-stage “one spray, three preventions”
The focus of late-stage wheat management is preventing pests and diseases, preventing premature senescence, and preventing dry hot winds. In order to save costs and increase efficiency and improve efficiency, in the late stage of wheat growth and development, all localities should formulate “one spray, three preventions” plans according to weather changes, seedling conditions and growth, and pest occurrence trends, reasonably mix insecticides, fungicides, foliar fertilizers or plant growth regulators, and spray them on the leaves 2-3 times from booting to the middle filling stage, to achieve the purpose of “one spray, three preventions.” All localities should adjust formulas according to local conditions to make the formulas more targeted, timely, and scientific. Regardless of irrigated or dryland wheat fields, the “one spray, three preventions” technology should be vigorously promoted.