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On May 9, the Henan Provincial Meteorological Bureau and the Henan Provincial Department of Agriculture and Rural Affairs jointly issued a high-risk warning of wheat dry and hot wind disasters. According to the monitoring, it is expected that the main period of the dry and hot wind disaster in Henan will occur from May 14 to 18, of which 11 places in Anyang, Puyang, Hebi, Xinxiang, Jiaozuo, Zhengzhou, Kaifeng, Shangqiu, Zhoukou, Xuchang and Luohe are high-risk areas for dry and hot wind disasters. In addition, in the late stage of wheat filling in May, wheat in many areas has appeared withered and white, which makes many growers very worried.
What causes it? Can it still be cured by taking medicine now? How much impact will it have on wheat yields? Will hot and dry air cause further harm?
The cause of the appearance of wilted white ears of wheat
In fact, wheat withered white ears is a common phenomenon in wheat production, generally manifested as the color of the ears is white to miserable white, the ears are thin or empty shells, the ears have a light feeling, once it occurs, it will seriously affect the yield and quality of wheat, the yield will be reduced by 10%, and the weight will be reduced by 50%, so we must pay attention to it. The factors that lead to the appearance of "withered white ears" in wheat are as follows: 1. Root diseases: root diseases mainly refer to wheat stem base rot, sheath blight, and root rot, which mainly harm the stems and roots, resulting in damage to wheat stalks or roots, and the formation of "withered white ears" can not effectively transport nutrients for wheat ears. 2. Hazards of scab: scab is a typical climatic disease, in the wheat flowering period in the rainfall, fog, humid weather, the fungus will enter the wheat glume shell with the pollen, in the wheat filling stage will form a "dry white spike", once the occurrence can be prevented and incurable.
3. Soil problems: soil compaction, soil acidification, soil salinization, pesticide residues and other reasons in some fields cause the soil is not suitable for the growth of wheat roots, coupled with the early aging of roots in the later stage, it will also cause the phenomenon of "withered white ears" of wheat and patches. 4. Causes of insect pests: insect pests mainly include straw flies, needleworms, etc. These pests will bite the rhizomes or stalks of wheat, resulting in the root system not being able to effectively supply nutrients to the wheat ears, resulting in individual wilted white ears.
5. Dry and hot wind: Dry and hot wind in wheat is a meteorological disaster in the late growth stage, which will also lead to white ears, affecting the wheat that is being filled, resulting in reduced yield. Under the influence of dry and hot wind, wheat will appear white ears, and at the same time, it will dry up early, increase the number of grains, and decrease the 1000-grain weight, which not only reduces the yield, but also reduces the quality. These are the causes of wheat wilting and white grain, and we should distinguish them according to the specific situation. As for the reasons for the appearance of wheat wilted white ears, some people in the industry went to the field to check and found that there are two main aspects: the first reason is scab, in late April, the northern region is generally rainy and low-temperature, and the field humidity is high, resulting in the outbreak of scab, and the plots where scab occurs will appear withered white ears. The second reason is mainly caused by the early sheath blight is not cured, especially this year, in the regreening period of the sheath blight outbreak, some growers did not use the medicine in time, or even did not use the medicine, although the later sheath blight did not continue to occur, but part of the wheat stem base is damaged, the root system is damaged, into the wheat filling stage, and because of the poor ventilation in the field, these plants that have had sheath blight in the early stage, sheath blight may continue to occur, and there will also be insufficient nutrient supply, thus causing wheat ears to turn white.
Is it still useful to take medicine now?
For the withered white corn caused by the above conditions, if it can be prevented and controlled in time in the early stage, the occurrence and spread of the disease can be effectively controlled.
However, now there is still about a month before the wheat matures, and there are withered white ears, which has a great impact on the yield. The main purpose of spraying pesticides now is to control the spread and prevent the disease to continue to spread in the later stage.
What drugs are effective in the prevention and control of wilted white ears?
In fact, whether it is the white spike caused by sheath blight or the white spike caused by scab, the choice of medication is actually the same, here are a few purely therapeutic formulas recommended to you:
1. Prothioconazole + tebuconazole, 30% propylthiobacterium is recommended. Tebuconazole 40ml spray per acre, this formula registers scab, the control effect is good, and it is effective for sheath blight and powdery mildew.
2. Cyanoxystrobin + tebuconazole, the drug cyanoxystrobin is also very effective in the field of prevention and control of wheat scab in China, and it is a special ingredient. 48% cyanostrobin is recommended here. Tebuconazole 50ml per acre of land will have a good therapeutic effect.
3. Fluconazole + fludioxonil, in this formula, fluconazole is a triazole fungicide, which is effective for scab and rust, and fludioxonil can treat sheath blight. 16% fluconazole is recommended. Fludioxonil, registered wheat scab, 40g per mu spray, can effectively control the withered white ears.
What is Wheat Dry Hot Air?
Wheat dry hot wind, also known as "drought wind", is a kind of agricultural disastrous weather with high temperature, low humidity and certain wind. When the maximum temperature reaches more than 30 °C, the air humidity reaches less than 30%, and the wind speed reaches more than 3 m/s, a mild dry hot air is formed. When wheat is in the grain filling stage, it is a critical period for yield formation, grain weight increase, and also a critical period for preventing dry and hot wind.
Henan's wheat sowing area this year is more than 85 million mu. According to the data of the meteorological department of Henan Province, the suitable proportion of soil moisture in the province is 48%, and the proportion of drought is 32%, and the drought in northern Henan, central Henan and eastern Henan has developed.
In the next 10 days, the province will be dominated by sunny to cloudy weather, with high temperature and low precipitation, and the risk of dry and hot wind disasters in most areas of northern Henan, central Henan and eastern Henan is high, so it is necessary to strengthen prevention.
Hazards of hot and dry air
Dry and hot air has a great impact on wheat yield, which can reduce the yield by about 5% at least and by 10%~20% at worst. When hot and dry wind occurs, the temperature increases significantly, the humidity decreases significantly, and there is a certain wind, transpiration intensifies, the water absorption capacity of the root system decreases, the photosynthetic intensity decreases, the dry matter accumulation ends early, and the filling period is shortened, which often leads to insufficient grain filling, serious grains, and even wilting and death of wheat. High temperature can also strengthen grain respiration, increase consumption, reduce accumulation, and further reduce grain weight. Wheat is prone to dry and hot air hazards during the grain filling stage, which will affect the quality of wheat grain filling and then reduce the wheat yield.
Precautionary measures
The first is to continue to do a good job in the full coverage of "one spray and three preventions". It is necessary to take "one spray and three preventions" as the top priority of current agricultural production, strictly implement the requirements of full coverage, continue to fight the battle of wheat stripe rust prevention and control, pay close attention to the strict prevention of dry and hot air, and create conditions for extending the filling time of wheat and improving the quality of grain filling.
The second is to do a good job of foliar fertilizer spraying in a timely manner. Before and after the arrival of dry and hot wind, it is best to spray foliar fertilizers such as potassium dihydrogen phosphate and amino acid water-soluble fertilizer before 10 o'clock in the morning every day, insist on spraying every 3-6 days for high-yield plots, and strive to spray 3-5 times during the wheat filling period to improve the phosphorus and potassium content in wheat straw and enhance the ability to resist dry and hot wind. Boron and zinc fertilizers can also be sprayed to accelerate the later development of wheat, enhance its stress resistance and firmness, and improve the filling speed and grain fullness.
The third is to increase moisture and cool down. Plots with integrated water and fertilizer facilities can be irrigated with small water by micro-spraying or drip irrigation a few days before the arrival of high temperatures, so as to reduce temperature, improve moisture and improve defense capabilities.
Fourth, strengthen monitoring and early warning. It is necessary to pay close attention to weather changes, strengthen communication and consultation with meteorological departments, focus on preventing meteorological disasters such as "dry and hot winds", release early warning information in a timely manner, strengthen emergency duty, implement disaster prevention measures in advance, make material reserves and technical preparations, and actively guide agricultural insurance institutions to intervene in disaster prevention as soon as possible.
In addition, under the influence of the Northeast low vortex and trough, the Henan Provincial Meteorological Observatory predicts that from the afternoon of May 10 to the morning of the 11th, there will be a strong convective weather process in the province, with scattered showers and thundershowers in the province, and some counties and cities in the west, north and southeast will be accompanied by strong convective weather such as 8 to 10 thunderstorms and gales, short-term heavy precipitation, and hail. Strong convective weather such as thunderstorms and strong winds may cause wheat spot lodging and affect the normal grain filling of wheat, so it is necessary to take precautions.
Source丨Daily Agricultural Materials, Agricultural Technology Lecture Hall, China News Network, etc., Nong Caijun Comprehensive Editor丨Nong Caijun Contact Nong Caijun丨18565265490
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