The key point of rape overwintering is to strengthen seedlings and prevent freezing.

At present, when rape enters the overwintering period, we should focus on the following field management measures around strong seedlings and anti-freezing.

Due to seedling fertilizer: rape seedling fertilizer is very important to improve the seedling quality and enhance the ability of freezing resistance. When transplanting rape, the fields with sufficient fertilizer and vigorous growth can not be applied, and those with steady growth can be applied less, but not enough for late sowing and late planting and base fertilizer. At present, weak seedlings and stiff seedlings with poor growth (there are only about 3 leaves) or rape fields with uneven growth should be supplemented with fertilizer as soon as possible. Organic fertilizer is the main fertilizer, and the fields with thin plants can increase the application of urea by 5kg / mu to promote the transformation of seedlings and strive for strong seedlings to survive the winter.

Clearing ditch and regulating soil moisture: waterlogging is an important obstacle to the high yield of rape. For the fields that have not been ditched, it is necessary to seize the favorable opportunity to surprise open the ditches inside and outside the fields, improve the ability of drainage and waterlogging reduction, avoid the alternation of freezing and thawing, and aggravate the freezing damage. It is necessary to deepen the dredging of the fields that have been opened and not matched, especially to add horizontal and vertical ditches, connect the ditch head, keep the ditch system unblocked, ensure smooth drainage, stop rain and dry fields, and prevent serious waterlogging damage caused by continuous overcast and rainy weather in winter and spring. When opening and clearing ditches, the ditch soil should be evenly covered in the rape roots, especially the "tall seedlings" root neck should be buried in the soil to avoid burying seedlings and causing lack of seedlings.

Rob warm to remove: for grass damage up to standard fields, we should seize the favorable opportunity of sunny, warm and high temperature, and choose the right medicine to eliminate as soon as possible. In general, more than 50 grass weeds per square foot and more than 10 broad-leaf weeds per square foot must be removed. Use medicine in sunny days with a daily average temperature of more than 5 ℃ in order to improve the effect of chemical control and avoid drug damage. The weeds of Gramineae in rape field can be controlled by high-efficiency fluoropyrin or triflurazine, and the broad-leaved weeds such as calamus and Niufanyao can be controlled by herbicide. The mixed fields of monocotyledon and dicotyledonous weeds can be mixed with the above-mentioned drugs or their mixtures, or they can also be artificially pulled out in combination with ploughing in winter and spring.

Covering and anti-freezing: transplanting rape with plate stubble should do a good job of loosening the soil and blocking the root in winter and spring, and protect the root to keep warm and prevent frost. Straw mulching is used to achieve the combination of straw returning to the field and rape field mulching in winter, generally evenly covered with 150 to 200 kilograms of rice straw per mu to enhance the cold tolerance of rape. For rapeseed seedlings grown without paclobutrazol chemical control and early sowing and early planting in the third leaf stage, 15% paclobutrazol wettable powder 60g / mu with 30kg water spray should be used before overwintering, so as to achieve the effect of dwarfing, greening and anti-freezing. Zuo Hailin