Summer Management of Welsh Onion

Welsh onion likes low temperature and humid environment, the suitable temperature for growth is 15 ℃ 25 ℃, more than 26 ℃, the growth is weak and slow, and it goes into semi-dormancy state above 30 ℃. The first stage is from planting onions to bursting, and this period is the period when the temperature rises from 15 ℃ to 25 ℃, which is more suitable for the growth of green onions. Therefore, after planting slow seedlings, they quickly entered the first growth peak, and 4Mel protruded a leaf in 5 days. At this time, strong seedlings should be selected, spring onions should be planted early, and fertilizer and water management should be strengthened. The second stage is from the middle of July to the end of August, when the summer is hot and hot. At this time, the green onion grows slowly, and it takes 10 days to reach out a leaf, the disease resistance is weakened, and it enters a semi-dormant period, so we should strengthen ploughing and weeding, pay attention to drainage and pest control. In the third stage, from the end of August to the middle of October, the temperature decreased, the temperature difference between day and night increased, and the growth rate of green onion accelerated. 3Mel stretched out a leaf in 4 days, elongated and thickened blue and white rapidly, and entered the second growth peak. At this time, it is necessary to fertilize in time, strengthen ploughing and soil cultivation, promote the growth of green onions and increase the yield. The main diseases of scallions are purple spot, downy mildew and rust. The prevention and control of purple spot and downy mildew are mainly foliar spray of chlorothalonil, pyrethrum and antidote alum after rain. Rust is a small brown protuberance on the surface of onion leaves, which can be prevented by spraying powder rust in time after rain. The main pests of green onions are ground maggots, leaf miner and onion thrips. Ground maggots are sprayed with trichlorfon once every 10 seconds and 12 days after the Beginning of Autumn, which has a good repellent effect on adults. After occurrence, it can be reported with 90% trichlorfon 800ml 1000 times solution. Submersible leaf rope and onion thrips can be sprayed with dimethoate, kung fu and intimidating enemies. There is a layer of wax powder on the onion leaves. No matter what kind of drug spray is used, 1% neutral detergent must be added to the solution as a display agent, so that the drug can be attached to the leaf surface to play a role, otherwise the spray is ineffective.