Causes of Yellow Leaf Disease in Corn and Nutrient Deficiencies Behind Albino, Purple-Red, and Other Abnormal Seedlings, with Prevention and Control

During the growth of corn, the leaves of corn seedlings may undergo changes, and this is mostly caused by a lack of elements essential for corn growth in the soil. So what is yellow leaf disease in corn? And what nutrients are lacking when albino seedlings and purple-red seedlings appear? How should they be prevented and controlled?

What is yellow leaf disease in corn?

Corn is a zinc-sensitive crop, and zinc deficiency can cause albino seedlings that look like yellow corn seedlings. Generally, zinc fertilizer is best applied as a base application;

1. Nutrient deficiency

If zinc deficiency is found during the growing period, symptoms of stunted height and small leaves will appear. You can spray Demer Tianye corn foliar fertilizer or sugar alcohol chelated zinc for efficient, safe, and rapid zinc supplementation.

2. Sowing too deep

Sowing too shallow makes it difficult for seedlings to emerge, while sowing too deep can produce weak and yellow seedlings. The sowing depth should be controlled at 3-5 cm; at the same time as sowing, apply a certain amount of seed fertilizer to promote seedling growth. For example, applying 3 kg of diammonium phosphate per mu at sowing can effectively prevent yellowing of corn seedlings.

3. Failure to thin and finalize seedlings in time

After corn emerges, thinning should be carried out at the 3-4 leaf stage and final seedling setting at the 6-7 leaf stage, to avoid crowding of young seedlings and competition for fertilizer, water, and light, which can form weak, diseased, and yellow seedlings; the number of seedlings retained per mu should be flexibly controlled according to different varieties, and seedling setting should follow the density required by the cultivated variety.

4. Insufficient watering

If watering is insufficient before or after sowing corn, the seeds cannot obtain enough moisture, which affects normal germination and emergence, and a prolonged emergence time causes weak seedlings and yellowing at the seedling stage.

5. Disease

If the seedling stage encounters long-term low-temperature and rainy weather, it can cause the occurrence and spread of corn seedling blight. Seedling blight mostly begins at the 2-3 leaf stage. The leaves of diseased seedlings turn yellow and dry up, with scorched edges, and the leaves gradually turn yellow and dry from bottom to top; root hairs are fewer, the root system turns brown and develops poorly, resulting in yellow and weak seedlings.

6. Waterlogged seedlings

The corn seedling stage often coincides with the rainy season, and poor drainage in low-lying plots or water accumulation in areas compacted during wheat harvest can cause yellow seedlings.

7. Herbicide damage

Improper use of herbicides, arbitrarily increasing the herbicide dosage, blindly mixing with other pesticides, using too high a concentration, sharing sprayers, and the impact of counterfeit or substandard herbicides on subsequent crops can all cause yellow corn seedlings.

8. Insect pests

The main insect pests at the corn seedling stage include cotton bollworm, wireworm, aphid, armyworm, thrips, Swedish stem fly, cutworm, and corn root mealybug. The corn root mealybug, with nymphs and female adults, gathers at the stem base near the soil surface, roots, and inside leaf sheaths of corn seedlings, sucking sap, causing the leaf sheaths of affected corn to turn yellow and dry up first.

Prevention and control measures: First, select good seeds before sowing, remove shriveled, moldy, damaged, and small grains, and ensure that seed cleanliness and purity are both above 98%, and the germination rate is above 90%. Second, germinate seeds before sowing, using seed coating or soaking seeds in fertilizer water. Third, thin seedlings in time, removing small, weak, and diseased seedlings and field weeds at the 3-4 leaf stage of corn. Fourth, after thinning, supplement nitrogen fertilizer to promote early and rapid seedling growth. Fifth, if there are dry clods of soil before and after emergence, break them up promptly.

What is going on with albino corn seedlings?

Generally starting from the 4-leaf stage, the leaf color at the base of new leaves becomes lighter and appears yellowish-white. At the 5-6 leaf stage, the 1-3 leaves below the central leaf show stripes alternating pale yellow and pale green, but the veins remain green, and purple stripes appear at the base. After 10-15 days, the purple gradually turns yellow-white, the leaf mesophyll becomes thinner, appearing as “white seedlings.” In severe cases, the entire field turns white. Zinc-deficient corn plants are short, with short internodes, overlapping leaf collars, and slow growth of the central leaf, appearing flat-topped. In severe cases, the white leaves gradually dry up, and even the whole plant dies.

Cause: Zinc deficiency in the soil.

Prevention and control measures:

1. Use zinc fertilizer as seed fertilizer, applying 1.5-2 kg of zinc sulfate per mu, mixed evenly with 15-20 kg of fine soil, and scatter it beside the seeds when sowing corn.

2. Mix zinc fertilizer with seeds. Mix 1 kg of zinc sulfate with 25 kg of corn seeds. The method is to use 2-3 kg of warm water to dissolve 1 kg of zinc fertilizer. After it is completely dissolved, spray the zinc fertilizer solution evenly onto the corn seeds so that the seed surface is coated with zinc fertilizer, then dry in the shade before sowing.

3. Spray zinc fertilizer on the leaves. For seedlings showing zinc deficiency, spray Demer Tianye sugar alcohol chelated zinc once every 7 days. Generally, 2-3 sprays can restore the seedlings to normal.

What is going on with purple-red corn seedlings?

The leaves and leaf sheaths of the seedlings change from green to red, and finally to purple. Symptoms generally appear at the 3-leaf stage of corn and are most obvious at the 4-5 leaf stage. The root system is poorly developed, the stem is thin and small, growth is slow, and the leaves change from green to purple. In severe cases, the leaves wither and die.

Causes:

Because the soil lacks phosphorus, the absorption capacity of the root system declines, chlorophyll synthesis is blocked, and the leaves change from green to purple. After corn emerges, if it encounters low temperatures, the corn leaves often also turn red or purple, but as the temperature rises, the red seedling phenomenon gradually alleviates and disappears later.

In addition, low-lying waterlogged fields, damage from underground pests, excessively clayey soil, sowing too deep or too shallow, seedling burning caused by improper fertilization, and seedling poisoning caused by improper chemical treatment can all lead to red seedlings.

Prevention and control measures:

Increase the application of phosphorus fertilizer as a base fertilizer. Generally, apply 40-50 kg of superphosphate per mu and fully decomposed fermented organic fertilizer as base fertilizer. Once purple seedlings appear, spray 0.2% potassium dihydrogen phosphate on the leaves 2-3 times; level the land, dig drainage ditches, and ensure that water dries after rain stops, with no water accumulation in the field.

What is going on with yellow-green corn seedlings?

The leaves of corn seedlings are narrow and thin, the plant type is short, and the leaves show stripes alternating yellow and green. In severe cases, the leaves become dark brown and finally scorch and die. Symptoms start from the lower leaves and gradually move to the upper leaves, greatly affecting yield and making lodging likely.

Cause: Potassium deficiency in the soil.

Prevention and control measures: Increase the application of potassium fertilizer. If potassium fertilizer has not been used, plant ash can be applied at the seedling stage. In cases of severe potassium deficiency, spray potassium dihydrogen phosphate or plant ash extract on the leaves at the 3-leaf stage. The effect is immediate, and the yield increase is obvious.

What is going on with stiff-leaf corn seedlings?

It mainly occurs before the 3-leaf stage of seedlings, showing small seedlings, pale green leaves, increased black roots, and soft, flaccid, and shrunken growth. After transplanting, except for the new leaves remaining green, the outer leaves turn yellow and stiff, stress resistance is poor, and dead leaves and dead seedlings easily appear.

Causes: Soil too hard; excessive fertilizer proportion, causing root burning and bud damage and resulting in stiff seedlings; soil too dry after sowing, etc.

Prevention and control measures: Reasonably regulate fertilizer, water, and air conditions. At the seedling stage, mainly use decomposed organic fertilizer, and do not use or reduce the use of urea as base fertilizer. Phosphorus fertilizer should be applied after composting. Keep the soil at suitable moisture, and transplant strong seedlings. For stiff seedlings that have already appeared, strengthen fertilizer and water management to promote recovery as soon as possible, and replenish seedlings promptly in severe cases.