Technical Guidance on Late-Stage Field Management of Summer Maize in the Huang-Huai-Hai Region

This year, the sowing period of summer maize in the Huang-Huai-Hai region was 3-5 days earlier than usual, the population uniformity was relatively good, and the overall growth was better than the usual level. However, affected by the relatively severe occurrence of El Nino, the temporal and spatial distribution of rainfall was uneven, drought and waterlogging occurred to varying degrees in some areas, and the overall growth process was delayed. At present, most summer maize in the Huang-Huai-Hai region is in the grain-filling stage, which is the key period for yield formation. In response to the recently continuously developing drought, the Ministry of Agriculture organized relevant experts to conduct consultations and put forward field management technical measures to strengthen management, combat drought and reduce disasters, and strive to achieve another bumper maize harvest.

First, actively irrigate and drain to protect ears and increase grains. When soil moisture content is below 60%, irrigate in a timely manner according to soil moisture and seedling conditions to meet the water demand of maize during the grain-filling stage and avoid forming a “neck-choking drought.” There is a relatively high probability of rainfall in the middle and late stages of maize growth, so it is necessary to prevent a sudden shift from drought to waterlogging, dredge drainage ditches in advance, promptly remove standing water from the fields, lower the water level and field soil moisture content, prevent waterlogging and lodging, reduce the occurrence of stalk rot, and ensure the normal development of maize tassels and ears and the smooth progress of later grain filling.

⟦NL> Second, apply fertilizer scientifically to promote grain formation and increase grain weight. This year, due to relatively heavy early rainfall, fertilizer use losses were relatively serious. For plots showing signs of fertilizer deficiency, scientifically topdress according to plant growth, and as far as possible apply urea between maize rows to prevent seedling burn. For plots where topdressing was not carried out in time at the large trumpet stage, quick-acting nitrogen fertilizer should be supplemented as soon as possible; for some plots with yellowing leaves and weak root absorption, spray a mixed solution of urea and potassium dihydrogen phosphate on the leaves to promote dry matter accumulation and increase grain weight.

Third, prevent diseases and control insects to reduce damage. Diseases and insect pests are prone to occur in the late growth stage of maize and are relatively difficult to control. In the middle and late growth stages, promptly spray one round of insecticides and fungicides to reduce the base population of ear diseases and insect pests and alleviate diseases. Strengthen monitoring of diseases and insect pests, and promptly carry out unified prevention and control and mass prevention and mass treatment. Focus on controlling insect pests such as Asian corn borer, cotton bollworm, peach fruit borer, armyworm, red spider mite, and aphids, as well as diseases such as leaf spot disease and stalk rot.

Fourth, harvest late at the appropriate time to increase grain weight. Continue to vigorously publicize and promote the technology of delayed harvesting of maize to increase yield. When conditions permit, postpone the maize harvest period as much as possible to early October, and harvest after the black layer appears at the base of the grains and the milk line has basically disappeared, that is, after physiological maturity is reached, so as to maximize full grain filling and maturation of maize and increase yield. According to variety characteristics and later drying conditions, promote mechanical ear picking and mechanical grain harvesting to achieve integrated mechanical harvesting and stubble clearing.

Fifth, promote deep loosening, deep plowing, and straw return. Deep plowing and fine harrowing make drought and waterlogging less fearsome. In conjunction with land preparation before wheat sowing, actively promote deep loosening, deep plowing, and straw return technologies. Use large straw crushers to promptly crush straw finely and deeply plow it in, supplement nitrogen fertilizer, and accelerate decomposition; use heavy disk harrows to further chop straw and root stubble, and after harrowing, promptly deep plow and cover so that straw, fertilizer, and soil are fully mixed, effectively improving soil structure and enhancing the soil's capacity for water infiltration, water storage, fertilizer retention, and fertilizer supply, laying the foundation for sustained annual yield increases of wheat and maize.