Key Field Management Techniques for the Late Growth Stage of Corn

1 Remove field weeds and diseased or weak plants

With the widespread adoption of mechanized wheat harvesting, the shading of wheat straw and stubble reduces the control effect of herbicides, and weeds left in wheat fields also increase the difficulty of weed control. For plots where chemical weed control is ineffective and field weeds are abundant, timely cultivation and weeding should be carried out. Combined with weeding, pull out diseased corn plants, small plants, weak plants, off-type plants and tillers. Where the retained plant density is too high, plants should be removed appropriately to maintain a reasonable and good population structure in the field. In a corn field, there are always a certain number of plants that form barren stalks without ears or short small plants; they not only consume nutrients for nothing, but also affect the photosynthesis of other plants. Such plants that are showy but useless must be pulled out, so that the limited nutrients are concentrated on supplying normal plants. Corn can grow several ears, but only 1 matures, or at most 2. To promote early maturity and increase yield, each corn plant is best kept with only the uppermost 1 ear, and all others removed, so as to ensure plump grains in the main ear and increase yield.

2 Timely earthing up to prevent lodging

Because the Anyang area is windy in autumn, corn lodging is often caused. Therefore, after topdressing corn, earthing up should be done in time to prevent lodging. If lodging occurs during the corn growth period, it will seriously affect yield formation, and in severe cases can cause total crop failure. Earthing up can increase the formation of corn aerial roots and enhance the lodging resistance of corn.

3 Timely control of diseases, insect pests and weeds

In recent years, summer corn has basically adopted no-till direct seeding, and the damage from diseases, insect pests and weeds has shown a worsening trend. Diseases such as top rot, banded leaf and sheath blight, and stalk rot, and insect pests such as aphids, corn thrips, and corn borers, require strengthened forecasting and control work. In the middle stage of corn, focus on strengthening control of the Asian corn borer, armyworm, cotton bollworm and northern corn leaf blight and southern corn leaf blight, especially strengthening control of the Asian corn borer. In the late stage of corn, mainly control red spiders and aphids, adopting comprehensive measures such as detasseling, cutting silks, and spraying pesticides in the field. The best period for controlling the Asian corn borer is the whorl stage. Use 1.5% phoxim granules at 1 ~ 1.5 kg per 667 m2, put them into a large cola bottle, punch 7 ~ 8 small holes in the bottle cap, and apply to the whorl for control. For armyworm, use 20% fenvalerate emulsifiable concentrate at 40 ml per 667 m2, diluted with 60 ~ 75 kg of water for spraying. For aphids, use 40% omethoate emulsifiable concentrate at 1 000 ~ 1 500 times liquid for spray control. For northern corn leaf blight, from the late heart-leaf stage to the tasseling stage or at the early stage of disease onset, spray 50% carbendazim wettable powder at 500 times liquid, or 75% chlorothalonil wettable powder at 800 times liquid, once every 10 d, for 2 ~ 3 consecutive treatments.

4 Appropriately delayed harvest

Under the condition of not affecting the sowing of the subsequent crop, harvest should be appropriately delayed. Harvest when the corn husks turn white, become loose, the kernel milk line disappears, and the contents are completely hardened. Experiments have shown that for each 1 d delay in harvest, the 1000-grain weight increases by about 3 g per day on average. This technique does not increase any input, but the yield-increasing effect is obvious.