What should we pay attention to during the wheat heading period?

Attention should be paid to field moisture management and pest and disease control during the wheat heading period. During the wheat heading period, we mainly control head blight, powdery mildew, aphids, and midges, which are also the main pests and diseases in the entire main wheat-producing area.

1. Head blight

Scab is the most serious disease in the main wheat producing areas in the Huaihe River Basin and the middle and lower reaches of the Yangtze River. The disease not only causes yield damage, but also leads to a decline in varieties. , Wheat with excessive gibberellin content is not allowed to be used to grind flour because it can cause cancer in the human body. Therefore, this disease is likely to cause farmers to lose profits.

How does scab occur? The occurrence and prevalence of wheat scab are affected by factors such as climatic conditions, number of bacterial sources, varieties, and cultivation conditions. The disease has a wide adaptability to temperature, but has higher requirements for humidity. Research shows that when the relative humidity of the air is between 80 and 100, the spore germination rate is the highest, and if it is less than 72, it will not germinate.

How does scab infect wheat? It turns out that pathogenic bacteria that overwinter on field plant residues such as corn stalks, dry weeds, etc. will form ascospores in early to mid-May of the next year. The formation of ascospores reaches its peak around the time of wheat heading, and ascospores begin to mature and fly away. During the heading and flowering stage of wheat, the scattered ascospores invade the spikelets through the withered anthers under high humidity conditions, or directly from the open spikelets.

Therefore, when the wheat heading to flowering period encounters continuous rain, continuous heavy fog and other weather that will increase the air humidity, scab is prone to break out. This is why scab is prone to break out in the Huaihe River Basin and the middle and lower reaches of the Yangtze River all year round. The reason why the mildew is serious is that it always rains during the heading and flowering period!

2. Powdery mildew

Powdery mildew, as the name suggests, is a powdery mildew-like disease on the leaves. The occurrence of this disease is closely related to temperature and humidity. It likes high-temperature and sultry environments, so it is easy to get powdery mildew in plots where planting is too dense and the temperature is relatively high. In areas that are dry all year round, or when it is rainy during the wheat growing season, the temperature is always high. Cooler areas are less susceptible to this disease. And if there is high temperature weather two or three days after a rainfall, it will facilitate the occurrence of this disease.

3. Aphids

Everyone is familiar with aphids. In some places, they are also called aphids, honey bugs, etc. It is parthenogenetic, which means that females can reproduce without mating, which greatly shortens the breeding cycle; and during the growth period of wheat, the reproductive method is viviparous, that is, newly born aphids can directly cause harm to wheat. . It is precisely based on the above characteristics that aphids increase exponentially after wheat heading, and generations of grandparents gather together to damage wheat leaves and ears.

4. Midnight midges

Midloids mainly occur in the main winter wheat-producing areas of the Yellow River and Huaihe River basins, with one generation occurring every year or every year. Overwintering larvae usually emerge from their cocoons during the jointing stage of wheat. When wheat begins to boot, the larvae that emerge from their cocoons go to the soil surface to pupate, probably in mid-to-late April, in areas where middlings often occur. The poisonous soil or sand of phosphorus and phosphorus will greatly reduce the number of midges.

When the wheat begins to ear, the pupae on the soil surface begin to emerge into adults. The adults can mate on the same day and lay eggs on the ears. The egg-laying period is very concentrated, only 2-3 days. Most of the eggs laid at this stage are valid eggs, which are the main source of insects that cause damage to wheat and reduce yields. Therefore, spraying systemic insecticides during the heading stage is a critical period for preventing and controlling midrips. After the wheat blooms, although there are still adults emerging one after another, they generally cannot lay eggs on the wheat ears that have bloomed, so most of them are ineffective eggs.

What kind of medicine should be used during the heading stage of wheat?

For scab: tebuconazole, pyraclostrobin, benzyl and azoxystrobin can be used, and cyanide can be added in high-incidence areas. Agents with different mechanisms of action, such as meprostrobin or prochloraz, can delay drug resistance and improve control effectiveness.

For powdery mildew: In conventional areas, tebuconazole and pyraclostrobin can be used to prevent and control it.

For aphids and midges: It is recommended to choose nitenpyram, pymetrozine, and thiamethoxam, which are highly systemic and long-lasting ingredients; and compound them with high-efficiency cyhalothrin Use ester or bifenthrin to prevent wheat leafflies.

Finally, when spraying these chemicals, potassium dihydrogen phosphate is added to improve the stress resistance of the leaves and promote flowering and grain filling. Therefore, when using medication during this period, from the perspective of comprehensive control and prevention, it is recommended to use the following medication plan:

①General areas: high chlorine·thiamethoxam pentazole·pyrazolate/benzoate· Azoxystrobin potassium dihydrogen phosphate

② Areas with high incidence of scab: High chloride·Thiamethoxam Tebuconazole·Pyrazole pyrazole/Benzyl·Azoxystrobin Cyanostrobin/Prochloraz dihydrogen phosphate Potassium hydrogen.