Technical Guidance on Field Management of Wheat Before Winter (2015)

At present, winter wheat sowing has basically ended, and most is at the emergence stage. Overall, soil moisture conditions are good in all areas this year, the sowing period is suitable, sowing is concentrated, and sowing quality is good. According to forecasts from the meteorological department, the strongest El Nino event in 17 years will occur this autumn and winter and will continue until next spring, manifesting as higher winter temperatures, reduced precipitation in some areas, and sharp fluctuations in winter and spring temperatures, which is unfavorable for winter wheat production. In response to abnormal climatic conditions, the National Agricultural Technology Extension Service Center, together with the Wheat Expert Steering Group of the Ministry of Agriculture, has studied and proposed technical guidance on field management before winter, strengthening “drought resistance, vigorous growth control, and freeze prevention”, doing a good job in winter irrigation, compaction, chemical control, and pest, disease, and weed control, cultivating strong seedlings before winter, and ensuring safe overwintering.

(1) Timely winter irrigation to resist drought and protect seedlings. In the Huang-Huai, northern, and northwestern winter wheat regions, for wheat fields lacking soil moisture and wheat fields with straw return, rotary tillage sowing, and loose, unsettled soil, irrigate winter water at the appropriate time to protect seedlings for safe overwintering. Winter irrigation should generally be carried out when the daily average temperature is stable at 3-4°C, when the soil freezes at night and thaws during the day, and when water can infiltrate in time, ensuring completion before heavy freezing. Water-saving irrigation is advocated, flood irrigation is prohibited, and after irrigation, hoeing should be done promptly to loosen the soil and preserve moisture, prevent surface cracking, and avoid root damage and seedling death caused by air penetration.

(2) Compaction to preserve moisture, chemical control to prevent vigorous growth. Carry out timely compaction before overwintering, especially for wheat fields with straw return and cracks after watering, which can firm the soil, close cracks, reduce soil moisture loss, benefit seedling growth, and also control vigorous growth and promote strong growth. Compaction at the wheat seedling stage should note: press dry soil, not wet soil; do not compact when the soil surface is wet or when wheat seedlings have dew; use smooth-surfaced rollers, not corrugated rollers, to prevent mechanical damage to wheat seedlings. For wheat fields sown too early with excessively large and vigorous populations, spray growth inhibitors to control vigorous growth and promote strong growth, ensuring seedlings overwinter safely.

(3) Use water to regulate temperature and defend against cold waves. For wheat fields with higher temperatures, lacking cold-hardening, and early-sown vigorous growth, once cold wave weather occurs, freeze damage and seedling death are likely. Closely monitor weather changes, irrigate promptly before temperature drops, improve soil moisture, regulate the microclimate near the ground surface, reduce temperature fluctuations, and defend against cold wave freeze damage. Once freeze damage occurs, apply an appropriate amount of nitrogen fertilizer promptly, then water, to promote the recovery of frozen wheat.

(4) Control pests and diseases, chemical weeding. Closely monitor the occurrence of pests and diseases such as red spiders, cutworms, and sheath blight, and promptly carry out forecasting and control. Based on treating spring weeds in autumn, use chemicals at the appropriate time according to weed species, weed age, and soil moisture, and do a good job in chemical weeding before winter. In the Huang-Huai-Hai and northwestern regions, carry out from mid-November to early December, at the 3-4 leaf stage of wheat, and when weeds are at the 2-leaf-1-heart to 3-leaf stage; in the middle and lower Yangtze River wheat region, apply chemicals before overwintering on sunny days when the daily average temperature is above 5°C, ensuring no frost low temperature below 0°C occurs within 7 days after application, to improve weeding effectiveness and avoid phytotoxicity.

In addition, northern wheat regions should prevent livestock and poultry from grazing on green wheat, ensuring normal seedling growth and safe overwintering; in the middle and lower Yangtze River and southwestern wheat regions, rice-stubble wheat fields should promptly clear ditches and manage soil moisture, dredge irrigation and drainage systems, so that irrigation is possible in drought and drainage is possible in waterlogging.