Management of onion expansion period

When onion is planted, the expansion period is the key period, which determines the yield and quality. Onions generally grow in the middle soil layer, at this time to do a good job in water control, nutrition, prevention of bolting, prevention of diseases and insect pests and other management work. It needs more meticulous care than other growth periods, and the key points of management after entering the expansion period will be revealed for everyone one by one.

1. Water control

Onion expansion period is in the Summer Solstice season, the external temperature is high, receive light every day for a long time, water evaporation is very fast, and the bulb continues to expand, the bulb will stop growing due to lack of water, and the aboveground leaves will not lodge without water. Therefore, it is necessary to gradually increase the number of irrigation and the amount of irrigation, generally irrigating once in the morning and evening every day, and irrigating once a week. Dry weather, can shorten the interval, free watering, but should be thoroughly watered to keep the surface moist. When it is about to mature, stop watering, the skin will grow and fix, and then the irrigated skin will crack.

2. Nutrition

Before entering the expansion period, topdressing should be applied once, and compound fertilizer with long-lasting effect should be applied to maintain the demand of bulb expansion period. in the middle stage of bulb expansion, extra-root topdressing and spraying trace element fertilizer should be applied to prevent leaf yellowing due to element deficiency. In the later stage of expansion, topdressing should be applied once to promote maturity, but nitrogen fertilizer can be applied less, mainly phosphorus and potassium fertilizer. Because onions are mainly harvested bulbs, phosphorus and potassium fertilizer mainly help bulbs grow, nitrogen fertilizer is easy to greed green, only grow leaves, leaves are too tall and easy to lodge, reducing light and effect.

3. Prevent bolting

Onions are mainly harvested bulbs, and the quality of bulbs needs to be maintained, so if bolting is found in the field, it must be cut off quickly to avoid bolting consuming nutrients and causing bulb hollowness. In addition, bolting consumes nutrition, and the bulb can not expand and stop growing. Generally pay attention to temperature management, sudden low temperature, easy to induce early bolting.

4. Disease and pest control

Onions are most prone to seed flies and downy mildew in summer, and seed flies are also called root maggots, mainly because eating bulbs can also cause leaves to rot and wilt, so focus on prevention and treatment, generally 40% phoxim can be used for root prevention and treatment. Downy mildew mainly harms the leaves on the ground, and the disease turns yellow and rotten and grows a large amount of white mildew layer, which seriously occurs when the humidity is high, so 70% chlorothalonil 600 times liquid can be used to spray during the expansion period. The interval between filling roots is about a week, and it is enough for two times in a row. Spraying can be done at intervals of three days and can be controlled three times in a row.

The expansion period is not only a critical period, but also a fragile period, requiring special care, so that none of the work to be done during the onion expansion period can be neglected, so that we can safely get through the expansion period and obtain the desired yield and better quality.