First, timely fertilization and watering.
After beginning of autumn, when the plant grows faster, it should be topdressing with "attacking leaf fertilizer", and applying decomposed farmyard manure 1500 kg ~ 2000 kg and calcium superphosphate 20 kg ~ 25 kg per mu to promote leaf growth. It is a key period for the formation of Welsh onion yield to enter the peak growth period after the Millennium. It is necessary to apply "attacking tree fertilizer" twice in coordination with watering, and apply urea 15 kg ~ 20 kg and potassium sulfate 10 kg ~ 15 kg between rows each time. Water after shallow tillage, generally 2-3 times. The principle of watering is that the soil on the ridge is dry and the soil in the ditch is wet.
Second, cultivate the soil in time
Onion grows fast. Only by cultivating the soil for many times in time can it grow fast and thick, which can be divided into 4-5 times. The height of each time is mainly cultivated in the heart of onion and cannot be buried. Too shallow soil cultivation is not conducive to the rapid growth of onion stems, and too much soil cultivation causes rotten hearts, resulting in reduced production or yellow leaves.
Third, timely control pests and diseases.
Onion diseases and pests include downy mildew, black mold, purple spot, leaf miner, root maggot and so on. 300g of "new high-fat film" emulsion and 230-250kg of water are added to each mu of land and sprayed evenly for 2-3 times every 7- 10 day, thus effectively preventing and controlling downy mildew of scallion. Black mold, sprayed with 50 kg of 0. 1% copper sulfate or 1% lime water or 0. 1% potassium permanganate solution. Purple spot disease is sprayed with 80% zineb 0.5% aqueous solution or 50% Jiatuo 0. 1% aqueous solution or copper sulfate, quicklime and water according to the ratio of 1: 1: 200, and the dosage per mu is 50 kg. Apply 5 kg methamidophos powder or 3.5-4.5 kg 2.5% trichlorfon powder or 2.5 kg phoxim granules to root maggots per mu of soil. Red spider can be controlled by 3000-3500 times of fenguangling or 2500-3000 times of red and white mites.