Beware of virus disease in rape seedlings

The characteristics of rape seedling virus disease in seedling bed are as follows: 1. During soil preparation, when applying farm manure such as pig manure, cow manure, chicken manure and so on, rape seedlings do not suffer from the disease. 2. No farm manure was applied, but only ammonium bicarbonate was applied to the seedling bed, the disease of rape seedlings was serious. 3. With the same variety and the same amount of fertilizer, rape seedlings did not occur in the seedling bed with high fertility, but rape seedlings in the seedling bed with low fertility. 4. in the seedling stage (September 1-October 1), the disease of rape seedlings was serious in dry weather, and the incidence of rape seedlings was light when there was more rain. Control methods: 1. Select disease-resistant varieties. Generally, the disease resistance of Brassica napus type is stronger than that of mustard type and Chinese cabbage type. In the investigation, it was found that Qinyou 7 had no disease or very mild disease because it was a variety of Brassica napus. 2, rape seedbed soil preparation, strive to apply human and animal manure and other farm manure 2000 kg / 667m2. No pig manure, cow manure and other farm manure, can be applied nitrogen, phosphorus, potassium ternary compound fertilizer not less than 30 kg / 667 square meters, boron fertilizer 500 grams / 667 square meters. Do not apply ammonium bicarbonate. 3. Rape seedling virus disease is mainly transmitted by aphids under natural conditions in the field. The control of aphid and disease is the key to the control of rape virus disease. For the affected plots, insecticides with contact and internal absorption effects are used to kill aphids to prevent the spread of the virus and prevent cabbage insects. 4. special attention should be paid to the seriously affected plots, which should be sprayed as soon as possible, and urea should be applied after spraying to prevent the lack of seedlings after transplanting in the field.