How to control dry-tip disease of green onion with albino and withering of leaf tip

Dried green onion tip

Acid soil causes dry tip: the neutral soil with pH 7-7.4 is the most suitable for the growth of Welsh onion. Less application of organic fertilizer and too much application of ammonium sulfate and calcium superphosphate will make the soil acidified, resulting in slow growth of onion leaves and yellow outer leaves. Control measures: apply enough mature organic fertilizer and 150 kg calcium oxide per mu.

Drought causes dry tip: do not pay attention to watering, soil drought, green onion lack of water is easy to cause dry tip. Control measures: timely and appropriate watering according to the different demand for water in different growth stages of Welsh onion. Seedling stage: properly control water, do not dry, irrigate once every 15-20 days; vegetative growth period: combined with topdressing and soil cultivation, timely watering to ensure sufficient water, so that the field capacity is 70%-80%; harvest time: 10-15 days before harvest control watering, field capacity is 60%-70%.

Lack of trace elements caused dry tip: calcium deficiency heart leaf tip yellowing, magnesium deficiency outer leaf tip yellowing. Prevention and control measures: trace element fertilizer can be applied outside the root, such as 0.1% calcium nitrate and 0.1% magnesium chloride spray.

The dry tip caused by high temperature and freezing injury: the growth temperature range of Welsh onion is 7 ℃ ~ 35 ℃, when the growth temperature is more than 35 ℃, the leaf tip dries up, when the leaf tip is below 7 ℃, the leaf tip is frozen and the leaf tip turns white. Control measures: for Welsh onion cultivated in open field, pay attention to watering and cooling; for those cultivated in greenhouse, strengthen ventilation, prevent high temperature above 30 ℃, strengthen heat preservation, and make the minimum temperature not lower than 7 ℃.

Toxic gas causes dry tip: applying ammonium sulfate or ammonium chloride in a closed environment will cause ammonia harm and soil acidification will cause nitrous acid gas harm. Ammonia withered the leaf tip and gradually turned brown; nitrous acid made the leaf tip white and withered. Prevention and control countermeasures: one is to release the air; the second is to increase the application of organic fertilizer and not to apply ammonium carbonate under the condition of airtight release; the third is to use the original dew of EM to irrigate the root or spray to relieve the harm, the specific usage is to irrigate the root once with 500x solution and spray with 1000 times liquid, once every 7 days, twice in a row.

The drug damage causes the dry tip: the concentration of the agent is too high, which makes the leaf tip of green onion turn white and dry. Prevention and control measures: grasp the reasonable concentration of the solution, spray 0.05% nucleotide AS (Lufeng 95) 500x solution to relieve the drug damage, or spray with Tianyi EM 500 × 800x solution in the early morning or evening, once every 7 days, 2 times in succession.