How is corn baldness caused? How to prevent and cure it?

Corn baldness refers to the phenomenon that the top of the ear of corn is not strong and the grain is not full, commonly known as bald or bald tip, which is one of the main reasons that affect the stable yield of corn, and in serious cases, it can reduce the yield by 20% and 30%. Therefore, effective measures should be taken to reduce and prevent baldness in production. So how is corn baldness caused? How to prevent and cure it?

First, the cause of baldness

Maize female floret differentiation, silking and grain formation begin at the middle and lower part of the female ear, then go up or down at the same time, and finally encounter environmental discomfort at the end of the top, and the top floret or fertilized embryo is often aborted due to insufficient nutrient supply. In addition to the genetic characteristics of maize varieties, the main reasons for maize baldness are as follows:

1. Nutritional deficiency

Phosphorus deficiency in soil affects cell division. Especially in the filament elongation period, phosphorus deficiency filament elongation is slow, which affects pollination. If the grain at the top of the ear is small and abnormally white, it is characterized by phosphorus and potassium deficiency, especially potassium deficiency.

two。 Spikelet degeneration

The spikelet at the top of the ear is degenerated and deformed, sometimes monoecious or male flowers develop while female flowers do not develop. It affects the normal pollination of corn and is difficult to bear fruit.

3. Filaments develop late

The filaments at the top of the ear develop late and the silking is delayed, which often makes the male flowers not pollinated in pairs, so that they can not bear fruit.

4. Dry and short of water

The most suitable temperature for corn flowering is 22-26 ℃, and the most suitable relative humidity is 65% ℃ 90%. When the temperature is higher than 30 ℃ and the relative humidity is less than 60%, the flowering decreases significantly; when the temperature is higher than 38 ℃, the male ear does not bloom. Maize encountered drought during flowering and pollination, and the interval between male and female flowers was prolonged, resulting in missing the peak period of scattered pollination of male ears when protruding from the filaments, resulting in adverse pollination. It can also cause the top floret to degenerate into sterile flower due to drought or lack of fertilizer in the process of differentiation.

5. Excessive close planting

Excessive planting density results in poor ventilation and light transmission in the later stage of maize growth, which affects the normal growth of maize.

6. Lack of micro-fertilizer in soil

Boron deficiency in soil had adverse effects on pollen formation and pollination activity of maize male flowers. When zinc deficiency occurs, the leaves of the old seedlings appear white spots and expand rapidly, forming local white areas and necrotic spots, and the internodes are shortened, which can easily lead to abnormal ear growth and development and lead to baldness.

7. The occurrence of diseases and insect pests

The occurrence of all kinds of maize leaf spot, maize seedling blight, sheath blight and stem rot can affect the normal growth and development of maize, resulting in poor growth of maize, especially a large number of maize aphids begin to occur when maize is heading. As a result, corn can not bloom and pollinate normally, resulting in bald tip lack of grains.

II. Prevention and control measures

1. Selected improved varieties

Coated seeds with high yield, full grains and strong vitality suitable for local planting should be selected, and they should be treated by drying and seed dressing before sowing.

two。 adequate manuring

Fertilization should be combined with nitrogen, phosphorus and potassium, and appropriate application of micro-fertilizer. Land with low fertility should be heavily fertilized, but attention should be paid to the weight in front and light in the back to prevent greedy green and late ripening. Watering should be controlled at the seedling stage to promote the differentiation of young ears, shorten the interval between male and female silking, and increase the chance of pollination. Do it in fertilization: re-apply base fertilizer. Apply enough farm manure, phosphorus and potash fertilizer as much as possible. For medium fertility fields, high quality farm manure 750kg / mu, urea 6kg, calcium superphosphate 50kg / mu, zinc sulfate 1.5kg / mu should be applied more or less. Skillfully apply ear fertilizer. Ten days before corn heading, that is, the big trumpet period, 25 kg of ammonium bicarbonate is applied per mu, and 3 kg of urea is applied per mu when the female ear begins to spin silk. Spray zinc fertilizer. 2% zinc sulfate solution was used to spray the leaves evenly at the jointing stage of corn.

3. Watering and pumping male flowering water

Corn is sensitive to water 15 days before heading, and when the soil water content in case of drought is less than 80% of the maximum capacity in the field, it should be watered immediately. It is beneficial to pollination and grain filling of corn. The fourth is artificial pollination. When the corn is in full bloom, it should be carried out in the morning when the dew is dry and the male flowers begin to disperse a large amount of powder. The rope pulling method or plant shaking method can be used every 2-3 days for 2-3 times in a row to prevent baldness.

4. Reasonable close planting

According to varieties, soil, cultivation methods and climatic factors, for the purpose of establishing high light efficiency population structure, reasonable close planting should ensure not only sufficient panicle density, but also good ventilation and light transmission conditions. The planting density is generally about 4000 plants per mu, the number of plants should be increased in the fields with good fertility, and the number of plants should be reduced in the fields with poor fertility. At the same time, it is best to use wide and narrow rows to avoid weak seedlings due to uneven fertilizer, water and light.

5. Moderate castration

According to the growth of the field and the heading of the whole field, artificial pollination can reduce the consumption of water and nutrients, improve the ventilation and light transmission condition of the upper part of corn, and increase the photosynthetic efficiency, which can not only reduce the formation of bald head, but also reduce the harm of corn borer.

6. Drought resistance and waterlogging drainage

Enhance the resistance to drought and waterlogging in time, eliminate the effects of adverse factors on maize growth, improve the field microclimate, enhance plant stress resistance, accelerate the synthesis and accumulation of photosynthates, and reduce baldness.

7. Control of diseases and insect pests

To control maize seedling blight, sheath blight and stem rot, we can choose 30% wettable powder which accounts for 0.3% of the seed quantity, or mix the seeds with 12% triazole EC and 12.5% diniconazole EC which account for 0.02% of the seed quantity. After diseased plants are found in the field, it can also be sprayed with 800x solution of 30% Miaomiaodui wettable powder, 800x solution of 50% methyl thiophanate wettable powder, or mixed spray of 80% Luheng No. 2 700 times 800 times and diluted 1000 times Tianda 2116. It has good control effect on maize seedling blight, sheath blight and stem rot.

Control of all kinds of leaf spot in the middle and later stages of maize growth, when corn leaf spot occurs, 50% methyl topiramate wettable powder 800 times or 50% carbendazim wettable powder 800 times can be used for spray control.

Control of corn borer at the end of corn heart and leaf stage, 3% carbofuran granule 3 kg: or after the occurrence of corn aphid, spray control with 1000 times of omethoate EC, 50 times of monocrotophos EC and 3000 times of imidacloprid wettable powder.