A new round of cold wave causes a sharp drop in temperature. Spring wheat beware of late spring cold.

The high temperatures of these days are just an illusion, and a new round of cold waves is already on the way. According to weather forecast, around 9 China will usher in a large-scale cooling. At present, wheat will enter the re-greening and jointing stage for six times. It is suggested that we should prevent the harm of late spring cold in advance. Once freezing damage occurs, it should be remedied in time.

Winter wheat damage

I. Hazard characteristics:

Late spring cold, also known as early spring freeze injury, refers to the spring temperature rise, due to the arrival of cold wave, and suddenly sharp cooling, the lowest temperature of about 0℃ weather. Because winter wheat enters the re-greening and jointing stage for six times after the beginning of spring, the cold resistance decreases. Therefore, when the cold wave arrives, the wheat is easy to suffer from freezing injury. In light cases, the wheat leaves are white and dry, just like boiling water at the initial stage; in severe cases, the young ears of wheat are frozen, and the ears cannot be drawn or deformed at the later stage. The wheat grains are missing, the number of grains per ear decreases, or even dies, and the wheat yield is reduced and heavy.

II. Defensive measures

1. Pre-disaster preventive measures: classified management. Combined with seedling situation and weather, wheat field classification guidance, strengthen field management, improve wheat cold resistance. For over-grown wheat fields,"control" should be given priority to, and measures such as spraying Zhuangfengan plant growth regulator, suppression and deep hoe should be taken to inhibit excessive growth of wheat, avoid early jointing of wheat, improve cold resistance and improve lodging resistance of wheat. The first fertilizer application in spring for vigorous wheat fields can be postponed to the late rising stage or around jointing stage. For general wheat fields, we should "promote control combination", first suppress, then shallow cultivation, in order to achieve the effect of temperature preservation. During the rising period, proper amount of topdressing and watering can promote tillering growth and strive for more ears. For weak seedling fields,"promote" is the main method, try to do early hoe, improve ground temperature, increase tiller roots, pay attention to shallow hoe, avoid damaging roots. After returning to green, quick-acting nitrogen fertilizer should be applied in combination with moisture content. As long as moisture content is acceptable in weak seedling fields, watering in early spring should be avoided to avoid lowering ground temperature. Topdressing watering is generally carried out in the late stage of returning to green or in the early stage of rising.

Watering before freezing: Watering before freezing is one of the effective measures to prevent cold in late spring. Before the arrival of late spring cold, the wheat fields with freezing injury must be watered in time to adjust the microclimate of the ground surface layer, which can significantly reduce the freezing injury.

Increase organic fertilizer application: in the jointing stage of wheat, increase organic fertilizer, phosphorus fertilizer and potassium fertilizer to promote root development, inhibit overground growth of wheat seedlings and enhance cold resistance.

Spraying regulator: Before the arrival of late spring cold, foliar spraying Tianda 2116 seedling spirit (grain special type) and other plant nutrients can improve wheat immunity and disaster resistance ability, reduce harm.

2. Post-disaster remedial measures:

Timely watering, fertilization: wheat adaptability is strong, where frozen wheat fields, as long as the tillering node does not die, through timely remediation, can strive for less or no yield reduction. After disaster, quick-acting nitrogen fertilizer should be applied in time to promote early seedling, multi-tillering and large panicle. General mu topdressing urea about 10 kg, after the temperature rises, quickly watering; or mu topdressing 30~40 kg ammonium bicarbonate, watering immediately after fertilization.

Timely spraying plant growth regulators: can spray "Tianda 2116", urea solution, potassium dihydrogen phosphate, etc.(prohibit mixing), can quickly repair the damage caused by late spring cold to wheat, help wheat restore growth, promote the rapid growth of medium and small tillers and latent buds, increase the number of ears and 1000-grain weight of wheat, reduce yield loss.

Placed hoe in time: Placed hoe can improve soil temperature, promote early growth of latent buds, effectively increase the number of tillers, make up for the loss of main stems.

Do a good job in pest control: frozen wheat fields are vulnerable to pests and diseases, so they should be closely monitored and prevented in time.