Aphids prevention is the key to control lettuce virus disease

Virus disease is the main disease of lettuce and lettuce, which is common. At present, there is no ideal chemical control at home and abroad. Prevention should be given priority to, and agricultural measures should be taken to control aphids in time. Virus disease is caused by virus infection, which is mainly transmitted by aphids in the field and through juice contact in agricultural operations. The number of diseased plants increased with the increase of air temperature. when the average temperature was more than 18 ℃ and water shortage for a long time, the virus disease developed rapidly. High temperature and drought, lack of fertilizer, extensive management, weak plant growth, many weeds, many aphids, serious disease. First, symptom identification. When killed at seedling stage, irregular mottles of light green or yellow and white were produced on the first true leaf, and the leaf margin was irregular or notched. The second and third true leaves have bright veins, followed by yellow and green mottled or mosaic. The symptoms of the adult stage were similar to those of the seedling stage, but some leaves shrunk, veinlets turned brown, brown necrotic spots, and some leaf edges curled and dwarfed. Second, control measures 1, select purple leaf lettuce and other disease-resistant or disease-resistant varieties. Collect seeds from disease-free plants. Root out the weeds in the field. Apply enough rotten manure, increase phosphorus and potassium fertilizer, water in time, and increase watering times when the weather is dry. 2. Lettuce and lettuce can be covered with aluminized polyester reflective film during sowing and planting. When planting in the open field, you can spread silver-gray reflective film as plastic film, or hang silver-gray reflective film strip in the field to avoid aphids. Sunshade net was used to cool down in the field. The seedbed can be sterilized with 50% thiophanate methyl 8-9 g / mu. 3. If aphids are found, spray shaoguan mycin 200 times, add 0.01% neutral detergent, or 0.65% anisinin 200 ml, add 60-80 kg of water. You can also use 10% aphid fumigant, 350 grams per mu, or 22% fumigant, or 20% aphid fumigant, 250 grams per mu, and smoke in an airtight greenhouse in the evening. Chemical agents to control aphids can be sprayed with 20% chrysanthemum and horse EC 1000 times, or 21% killing EC 4000 times, or 2.5% Uranus EC 3000 times, or 10% imidacloprid wettable powder 3000 times, or 25% imidacloprid wettable powder 2000 times, spray once every 7-10 days for 2-4 times. 4, seedling prevention, can spray 5% bacteriological dehydrated agent 300x liquid, or antiviral agent No. 1 water agent 300x liquid, or potassium permanganate 1000 times liquid, or 20% virus A wettable powder 500x liquid, or 1.5% Zhisanling EC 800x-1000 times, spray once in 7-10 days, 3-4 times in a row.