1. Strictly implement the quarantine system to prevent the introduction of germs.
To develop citrus in new areas and disease-free areas, we should use disease-free seedlings to build gardens. It is forbidden to transport seedlings, scions and rootstock seeds from ulcer areas, and it is forbidden to transport fresh fruits from this area for sale. Once found, it should be completely burned immediately.
2. Establish disease-free nursery and cultivate disease-free seedlings.
Especially in the ward, the disease-free nursery should be located on the plot far away from the citrus orchard (≥ 2000m) and separated by barren hills and forests. Rice is the best crop in the previous crop, and seedlings can be raised in plastic greenhouses if conditions permit. When raising seedlings, scion and rootstock seeds should be collected from disease-free or disease-free trees, and those that may get sick should be strictly disinfected (soak the seeds in 5% potassium permanganate or 1% formalin solution 10 ~ 15 minutes before sowing; Before grafting, the scion is soaked in 72% streptomycin 1500 ~ 2000 times solution+1% alcohol for 30 ~ 60 minutes, or soaked in 0.3% ferrous sulfate solution 10 minutes, and then washed with clear water). When the diseased plants are found, they should be pulled out and burned in time, pay attention to spraying protection and cultivate disease-free seedlings. Seedlings transferred from other places should be disinfected according to the above scion disinfection method, or sprayed with Bordeaux solution 1: 1: 100 to ensure the health of seedlings.
3. Give priority to prevention and take comprehensive prevention and control measures.
(1) Clean the garden thoroughly in winter and spring to reduce the source of bacteria. After harvesting or before germination in early spring, combine pruning, and remove the branches of diseases and insect pests, dead branches, cross branches, over-dense branches and aged branches cut from trees together with weeds, fallen leaves, fallen fruits and peels in the garden, dig out sporadic diseased plants and burn them centrally. After pruning, spray the crown carefully 1: 1: 65438. When spraying stone sulfur mixture or crystal sulfur mixture, 2,4-D of 10 mg/L can be added to the liquid medicine to reduce the abnormal defoliation of trees.
(2) Control pests and reduce the damage to branches and leaves. Pests that harm citrus buds, especially leaf miner, will cause a lot of wounds, thus increasing the chance of wound canker infection. The production practice shows that the occurrence of canker can be greatly reduced by controlling the new tip pests, especially the liriomyza sativae.
(3) Spraying drugs on the crown to protect the buds and young fruits. It is not necessary to dig out the diseased plants in the old and common wards, and the prevention and treatment should be based on spraying drugs, and must not wait until the diseased spots are found. The prevention and control should focus on the tender branch stage, young fruit stage and after heavy wind and rain. Seedlings and young trees mainly protect their shoots. Spray the medicine for the first time in spring, summer and autumn (the new bud is 2 ~ 3cm long), and spray it every 15 ~ 20 days until the new bud is mature. Results The fruit of the tree was mainly preserved, and it was sprayed for the first time on 10 ~ 15 days after flowering, and then once every 15 ~ 20 days, with a total of 1 time and continuous spraying for three times. After heavy wind and rain, spray medicine in time to prevent germs from invading from the wound. The medicament can be any one of the following: 1: 1: 200 bordeaux solution, 50% arsenic-zinc thiram wettable powder 500-800 times, 72% agricultural streptomycin 1000-3000 times, 50%. 500- 1000 times of 25% yekuzun EC, 400-600 times of 80% bordeaux wettable powder, 400-600 times of 77% copper hydroxide EC and 500-800 times of 30% copper oxychloride (copper oxychloride) suspending agent. When spraying drugs, we should be careful and considerate, and use drugs alternately to improve the control effect. In addition, spraying the mixture of copper and ammonia on the crown can also have a good effect. The specific method is as follows: put copper sulfate, quicklime, ammonium bicarbonate and water in a crock according to the ratio of 1: 2: 3: 6, mix and stir evenly, and seal for 5 days to make mother liquor. When in use, the mother liquor is diluted with water to 100 ~ 200 times of the sprayed liquid. After spraying copper preparations such as Bordeaux mixture, it is easy to induce red spiders and rust ticks. After 5 months, it should be stopped and replaced with other chemicals.
(4) Enhance the tree potential and prohibit the operation with water. In production, it is necessary to control the application of urea, ammonium bicarbonate and other quick-acting nitrogen fertilizers, increase the application of phosphorus, potassium fertilizer and organic fertilizer, spray foliar fertilizer frequently, cover trees well and irrigate and drain water in time. Therefore, trees should focus on applying fruit-strengthening fertilizer and fruit-picking fertilizer, remove all summer shoots and sporadic early autumn shoots, and strictly control late autumn shoots to enhance the resistance of trees. Pruning, wiping (picking) tips, picking leaves and picking fruits are prohibited. In rainy days and when the frost is still wet, this can prevent man-made spread of germs.