Key Points of Spring Field Management for Winter Rapeseed

1. Disaster Prevention and Mitigation to Promote Growth Recovery

According to forecasts from meteorological departments, the main rapeseed-producing regions will experience widespread rain, snow, and freezing weather in late January, which will adversely affect the growth and yield of rapeseed. Therefore, it is essential to strictly implement the “Three Resistances and Two Reductions” measures: cold resistance, moisture conservation and cold resistance, seedling strengthening and cold resistance, disease prevention and reduction, and compensation for losses.

1. Cold Protection Measures: Covering with cold-resistant materials to protect rapeseed seedlings from frost damage and adopting effective moisture conservation measures to enhance cold resistance. For fields affected by freezing, it is recommended to apply 3-5 kg of urea and 3 kg of potassium chloride per acre, and spray boron fertilizer and growth regulators to promote seedling recovery.

2. Freeze Damage Response: In downstream late-sowing areas such as Jiangsu and Anhui, and in rice-rapeseed rotation areas such as Jiangxi and Hunan, where the rapeseed biomass is insufficient and resistance is weak, unmanned aerial vehicles (UAVs) can be used to spray fluazinam or tebuconazole to promote new shoot growth and control sclerotinia.

3. Green Manure Utilization: For fields that are severely frozen and have failed, dead rapeseed plants can be plowed under to be used as green manure to improve soil fertility. Spring potatoes or fast-growing vegetables can be planted in time to reduce losses.

4. Dewatering and Drought Resistance Measures: To cope with the effects of continuous rain and waterlogging, especially in rice-rapeseed rotation areas, drainage ditches and waterlogging prevention facilities should be maintained in advance. In the drought-prone areas such as the Yunnan-Guizhou Plateau and Huanghuai region, soil improvement measures such as middle plowing, soil mounding, and irrigation or spraying should be adopted to improve soil moisture conditions.

2. Categorized Management to Promote Rapid Spring Growth

Based on the condition of seedlings, categorized management should be implemented to promote rapid spring development:

1. Vigorous Seedling Management: For vigorous rapeseed seedlings, paclobutrazol or daminozide can be used to control top growth and promote side branch development, thus improving yield. During the critical period of flower bud development (when the stem height exceeds 30 cm), the use of growth regulators should be avoided, and potassium chloride (3-5 kg/acre) should be applied to prevent lodging.

2. Weak Seedling Management: For weaker fields, combine soil cultivation with 10 kg of urea per acre to promote seedling growth. If the seedlings have already formed a closed canopy, UAVs can be used to spray brassinosteroids and other growth regulators to accelerate seedling transformation.

3. Strong Seedling Management: For fields with good growth, foliar spraying of potassium dihydrogen phosphate and boron fertilizer is recommended to promote strong spring growth and branching, enhance resistance to lodging, and improve pollination and seed setting rates, ensuring high and stable yields.

4. Boron Deficient Area Management: In areas where boron is commonly deficient (such as Hunan, Hubei, Jiangxi, etc.), especially in fields showing poor seed setting due to flower abortion, timely application of boron fertilizer should be made to improve seed setting rates and avoid yield losses.

3. One Promotion and Four Preventive Measures to Ensure Flowering and Pod Setting

During the flowering period of rapeseed, special attention should be paid to the impact of freezing on boron absorption and the occurrence of cracking and flower abortion. According to the specific conditions of different regions, the “One Promotion and Four Preventive Measures” integrated pest control strategy should be implemented.

1. Balanced Fertilization with Nitrogen, Phosphorus, and Potassium: Increase boron fertilizer during the early flowering stage and use a mixture of fluazinam and hymexazol as a substitute for traditional broad-spectrum fungicides, applying unified pest control to reduce disease occurrence.

2. Aphid Control: In the southwest and Huanghuai regions, where temperatures are higher, aphid infestations may intensify. Based on the “One Promotion and Four Preventive Measures” plan, the application of 40-60 grams of imidacloprid wettable powder (10% content) should be used for control.

3. Root Swelling Disease Control: In regions severely affected by root swelling disease, foliar spraying of rooting agents can induce new root growth at the base of the plants, allowing rapeseed to survive with disease. After 5 days, apply urea and potassium chloride to ensure plant recovery.

4. Timely Harvesting to Reduce Yield Losses

Rapeseed suffers a high loss rate during combined harvesting, and the quality of commercial seeds is often poor. Therefore, a combination of timely harvesting and mechanized segmented harvesting should be adopted to reduce losses and improve harvest efficiency.

1. Segmented Harvesting Technology: In areas with loose crop rotations, mechanized segmented harvesting of rapeseed should be promoted. It is recommended to use a cutter-dryer when about 80% of the rapeseed plants have turned to loquat yellow, drying the plants for 5-7 days, then using a self-propelled combine harvester to thresh. This method can effectively reduce harvesting losses.

2. Chemical Ripening Technology: In areas with tight crop rotations or insufficient segmented harvesting equipment, chemical ripening agents should be used in conjunction with mechanical harvesting. Spraying the ripening agents (via UAV) when rapeseed is 80% yellow, and harvesting 5 days later under sunny weather can improve harvesting efficiency and reduce loss rates.

By implementing the above technical measures, the challenges of spring field management for winter rapeseed can be effectively addressed, ensuring healthy growth, improving yield and quality, and ultimately achieving a bumper harvest.