Ministry of Agriculture issued Technical guidance on promoting early maturity and preventing early Frost of Maize in Northeast China in 2014

The climate conditions during corn sowing and emergence in Northeast China this year are generally favorable, with good matching of light and warm water. The overall growth of corn is better than that of perennial level, but in some areas, the sowing date of corn is delayed due to low temperature spring waterlogging, and the growth process is delayed. At present, Northeast maize is at the stage of tasseling and silking, and has entered the key period of booting filling and yield formation. In view of the possible early autumn drought and early frost in Northeast China affected by El Niño event this year, the Ministry of Agriculture organized experts to formulate technical guidelines for promoting early maturity and early frost prevention of Northeast corn, effectively strengthen field management, ensure safe maturity of corn, and strive to achieve a bumper harvest of autumn grain.

One is drought prevention and drainage to promote growth. The period from 10 days before tasseling to 20 days after tasseling is the period of most water demand, maximum water consumption and most sensitive to water in corn life. According to soil moisture content and seedling growth, proper amount of tasseling and grouting water should be poured in due time to effectively prevent "autumn hanging" and promote ear size and grain fullness. Northeast China is still in flood season in August, low-lying waterlogging prone plots should be drained in time to avoid serious yield reduction caused by waterlogging lodging.

Second, rational fertilization to increase grain and weight. According to soil fertility, seedling situation and early fertilization timely topdressing. For the fields with sufficient base fertilizer and intertillage topdressing and good growth, no topdressing can be used; for the fields with insufficient fertility, irrigation or effective rainfall can be combined in the big bell mouth period, deep fertilization can be carried out on the side of the row, urea 25- 30kg per mu can be applied, or 150- 200g potassium dihydrogen phosphate mixed with water 30kg foliar fertilizer can be sprayed per mu. The dosage of foliar fertilizer can be appropriately increased in high-yield fields to accelerate the growth process, prevent premature aging of leaves, enhance root activity, and improve grain number and grain weight.

Third, scientific medication to prevent and treat diseases and insects. In view of the fact that corn borer, armyworm, aphid, big spot disease, small spot disease, brown spot disease and other diseases and insect pests may occur more frequently in Northeast China this year, it is necessary to strengthen monitoring and early warning, scientifically select pesticides, popularize green prevention and control technologies such as Trichogramma control corn borer, black light lamp or sexual attractant trapping, comprehensively apply various measures such as overhead self-propelled mechanical spraying and flying prevention, and timely carry out emergency prevention and control. For the plants with diseases, the diseased leaves at the bottom should be removed in time and taken out of the field for centralized burning, so as to reduce the infection sources of germs.

Fourth, promote early maturity and prevent frost. Measures such as autumn ridging, taking large grass, cutting empty culms and diseased plants, priming leaves, removing ineffective ears, standing culms, peeling and drying, spraying potassium dihydrogen phosphate, etc. were adopted to improve field ventilation and light transmission conditions, reduce nutrient consumption and accelerate grain filling. Prevent premature removal of the upper and middle leaves of corn and promote the transfer of nutrients to ears. For late-maturing varieties and low-lying plots, rice husks, corn stalks, miscellaneous grasses, etc. can be placed at the upwind to ignite fumigation to improve local environmental temperature. Conditional plots can be sprayed with plant growth regulators such as chlormequat and chlormequat to enhance the ability to resist stress and cold.

Fifthly, timely late harvest dehydration and quality improvement. The harvest time of maize should be delayed as much as possible before the early frost, and the effective filling time of grain should be prolonged by making full use of the post-ripening effect of maize. It is best to harvest mechanically when the bract leaves are dry, the black layer appears and the grain milk line disappears. 10 days before harvest, spray corn dehydrating agent, 60- 100ml per mu, add water 15- 20kg, spray on three leaves of rod, accelerate seed dehydration, reduce water content, improve yield and quality. For greedy-green late-maturing plants, silage is harvested in time for feed. After corn harvest, it is stacked by means of yard, warehouse, ear and room, ear selection and classification, so as to accelerate dehydration and prevent seed mildew.

(National Agricultural Technology Extension Service Center of Corn Expert Steering Group of Ministry of Agriculture)