Technical guidance on field management of rape during overwintering in 2015

During the autumn sowing of rape this year, there were more Rain Water in the upper reaches of the Yangtze River basin, the harvest of rice in the middle and lower reaches of the Yangtze River was delayed and drought occurred in the middle and lower reaches of the Yangtze River. The sowing date of rape was generally delayed than usual, about 10 days in the upper reaches and about 5 days in some areas of the middle and lower reaches, resulting in greater differentiation of rape seedlings, 3-5 leaves less in the upper reaches than last year, and short seedling age, small seedlings and weak seedlings in some late-planted rape in the middle and lower reaches. According to the forecast of the China Meteorological Administration, the El Nino event may aggravate this winter, and there is a high probability of low temperature, overcast and rain and warm winter. In order to guide all localities to do a good job in the classification and guidance of rape seedlings, the National Agricultural Technology extension Service Center and the Oil expert guidance Group of the Ministry of Agriculture studied and put forward technical guidance for rape field management during the overwintering period.

(1) and time to replenish seedlings and rush to plant. Direct seeding rape planted early from 3-leaf stage and early seedling replenishment, weak and strong, impurity and purity, small and big, disease and health, density and evenness, 4-5 leaf stage fixed seedlings, direct seeding rape generally leave 12000-30 000 seedlings per mu, transplanting rape to ensure field density of 6000-8000 plants. The rape fields which have not yet been transplanted in the lower reaches should seize the favorable opportunity of the recent increase in rainfall and the improvement of soil moisture, grab the soil moisture and transplant early, and appropriately increase the transplanting density to make up for the late. Generally, not less than 7000 plants per mu, a maximum of 10, 000 plants can be planted.

(2) to clean up the ditch system as soon as possible to prevent drought. During the beginning of winter, continuous rainy weather often occurs in the Yangtze River basin, and low-lying fields are easy to form waterlogging disasters, resulting in anoxic rotting roots and weak seedlings of rape, reducing overwintering frost resistance, aggravating the occurrence of Sclerotinia sclerotiorum, and affecting yield and quality. The sowing time of Rain Water in the upstream area is on the high side, and drought may occur in winter. Once a strong cold wave is encountered, it may lead to the superposition of drought and freezing. Therefore, three ditches should be matched as soon as possible before the beginning of winter, and the ditches should be cleared in time to ensure the smooth flow of drainage and irrigation.

(3) do a good job in fertilizer and water management because of seedling classification. After transplanting rape turned green or direct seeding rape, the seedling fertilizer was increased according to 5-6 kg urea per mu, and wax fertilizer was applied again according to the seedling growth from late December to early January, 5-7 kg urea and 3-5 kg potassium chloride were applied per mu. Seedling wax fertilizer can not be applied to rape with sufficient base fertilizer, high density and strong growth, and seedling fertilizer should be applied as soon as possible for direct seeding rape with no base fertilizer or insufficient base fertilizer and late sowing date, as well as rape with slow growth and stagnant seedlings. 7.5 kg urea per mu is applied to promote growth and transformation, and seedling fertilizer can be applied to the uneven field to promote balance.

(4) spraying regulators to control prosperity and promote strength. Before entering winter, growth regulators such as Bibu and Panoke are sprayed with 40 kg of water per mu to promote winter growth and improve the ability of overwintering frost resistance. For overgrowing rape, 30-40 grams of 15% paclobutrazol per mu can be sprayed with 40 kilograms of water to control growth, prevent early bolting and early flowering, improve plant anti-freezing ability, and achieve strong seedlings overwintering.

(5) strengthen the management of diseases, insect pests and weeds. Under the influence of climatic conditions and field moisture, grass damage occurred early and quickly in the upper reaches, heavy monocotyledon weeds in rice fields in the middle reaches, and large weed base in no-tillage rape fields in the lower reaches. For the fields without closed weeding, the grass weeds should be sprayed with 20-30 ml of high-efficiency grass energy and 30 kg of water per mu as soon as possible, and the broadleaf weeds should be sprayed with 30 kg of high-tech water as soon as possible. At the seedling stage, the main control of quenching disease and downy mildew, quenching disease can be controlled with 95% chlorpromazine 4000 times liquid, if found that a large area of downy mildew occurs, can be used to prevent and control. Sclerotinia sclerotiorum is mainly controlled at bud bolting stage and early flowering stage. when the incidence of Sclerotinia sclerotiorum leaves reaches 10%, 1000 times of carbendazim ultrafine powder or 1000 times of 40% sclerotiorum net wettable powder can be used. Or methyl thiophanate suspension (active ingredient 36%) 1000 times foliar spray treatment, the drug can be used again at an interval of 7 days. In addition, in Yichang and other areas in the upper reaches of the Yangtze River and the middle reaches of the Yangtze River, in order to strengthen the prevention and control of rape root swelling disease, lime nitrogen can be used instead of traditional nitrogen fertilizer as topdressing, and chemical control can be applied with 50% carbendazim 600 times solution or dimethazon 500 times solution.