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Article source: Dr. Nong in action - Farmers Network

Why are the purple-red corn seedlings

2013-06-17?

The purple-red spring corn seedlings have become the focus these days, and there is an endless stream of farmers asking about this issue. To summarize the situation, first, the outbreak occurred in a wide area, involving Handan, Xingtai, Shijiazhuang, Hengshui, and Cangzhou. Second, the problems occurred at a concentrated time. The corns that were originally growing well have stopped growing in the past few days, and even the seedlings are dying. Third, the symptoms are mostly similar, with leaf lesions and root system being fine.

Let’s sort out the various situations. First of all, is it a disease or insect infestation? Some of the fields with the problem have thrips. The Cangzhou and Pingxiang consultation said that thrips have been serious recently. Thrip damage to corn can cause white marks on leaves and cause leaf distortion. Therefore, the appearance of purple seedlings is not closely related to thrips damage. The investigation showed that some of the dead and wilted seedlings were caused by underground pests. Because cutworms, wireworms, and Aedes mosquitoes are currently harming corn, the damage is still serious in some fields.

Corn seedling blight is also a disease that can cause the leaves of corn seedlings to change color. However, the disease is transmitted from soil and seeds. The roots are first broken and turn brown. Although the leaves are discolored in old leaves, the corn The seedlings did not turn purple obviously.

The second is the fertilizer issue. There are plots of land here that do not receive base fertilizer, but most of them receive base fertilizer normally. Therefore, there is some relationship with fat.

The third is a variety problem? The purple-red seedlings are not obviously concentrated in a certain variety, and it does not rule out that the problem of certain varieties is more prominent in some places. For example, I am planting sweet corn, which is very different from the varieties of other farmers, and the seedlings are also purple-red inexplicably.

The fourth is nutrient deficiency. Corn leaves will turn purple due to lack of phosphorus. Young corn plants are sensitive to phosphorus. The plants are dwarfed, the leaf tips and leaf edges turn purple-red, and the rear leaf tips die or turn into dark purple-brown; the root system is underdeveloped. This is the right number.

To sum up, the purple-red seedlings that appeared this year are widespread and not an isolated case. We have seen this kind of problem during the spring corn seedling stage in Chengde last year. Last year, the spring temperature in northern Hebei was extremely low, and many farmers reported that the corn was purple-red seedlings that did not grow. At that time, Teacher Ma Xiuying from the Chengde Plant Protection Station discussed the reasons and solutions with us. It was determined that low temperature caused phosphorus deficiency.

There are two situations that can cause phosphorus deficiency in corn. On the one hand, when the content of available phosphorus in the soil is low, the phosphorus supply is insufficient, causing the corn seedlings to turn purple; on the other hand, when the corn seedlings grow, they encounter low temperatures or watering, which causes damage to the root system, stunts development, and affects absorption. Phosphorus capacity; in addition, low temperature will reduce the availability of soil phosphorus. Even if the soil phosphorus content is high, it will cause the corn seedlings to turn purple.

The widespread phosphorus deficiency in so many places should not be due to the lack of phosphorus in the soil. It should be a large-scale influencing factor, which is climate. Looking back at the weather since June, everyone lamented that temperatures are usually very high and rain is scarce near the wheat harvest season. This year, it was cool in the morning and evening. On June 7th and 9th, there was widespread rainfall across the province, generally with moderate to heavy rainfall. The soil moisture content is high, but the temperature is low, which is not good for root development and phosphorus availability. The optimum temperature for the growth of corn in the seedling stage is 18-20 degrees. However, since June, especially when it rains, the night temperature is low. Moreover, since June, there are more cloudy and cloudy days, and the light intensity is low, which is not conducive to the photosynthesis of plants. Plants are not growing as well as before.

After analyzing the reasons, how should we manage it now to ensure that the corn seedlings return to normal growth? Several types of prescriptions can be prescribed.

The first is purple-red seedlings. Aidoshou 6000 times solution (or Yunda 120 1000 times solution) + 0.2-0.3% potassium dihydrogen phosphate + 1% urea solution + 10% difenoconazole 1500 times solution”, once every 7 days, ***Spray 2 times; or spray 500 times of Luoxiaowang + polymycin (Ag) once in the evening.

The second one is purple seedlings + 6000 times of Aidoshou ( Or Yunda 120 1000 times liquid) + 0.2-0.3% potassium dihydrogen phosphate + 1% urea liquid + 10% difenoconazole 1500 times liquid + 10% imidacloprid wettable powder 1000 times liquid for 7 days. Once, spray 2 times in the morning; or spray 500 times of Luoxiaowang + polyantimycin (Ag) once in the evening.

Add 10% imidacloprid wettable powder 1000 times liquid, and use imidacloprid once after 7 days.

The third is purple-red seedlings + underground pests. Aidoshou 6000 times solution (or Yunda 120 1000 times solution) + 0.2-0.3% potassium dihydrogen phosphate + 1% urea solution + 10% difenoconazole 1500 times solution”, once every 7 days, ***Spray 2 times; spread insecticide granules in the field, such as 1kg of 5% chlorpyrifos granules, or 2.5kg of 2.5% isofosate-methyl granules, mix with 25kg of fine soil, and spread along the ridge at the base of the corn seedlings in the evening

Please choose one of the prescriptions for prevention and control according to the situation in your own field. If the temperature rises faster, it will be beneficial to the recovery of diseased seedlings.

Li Suping from Pingshan Plant Protection Station

Source: Farmers Network

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