How to prevent and control cotton seedling stunting? These methods are worth trying

    After cotton is transplanted, it is right in the plum rain season, with low temperatures, many rainy days, and little sunlight, which causes the cotton seedlings to turn green slowly, delays flower bud differentiation, and forms the "stunted seedling" phenomenon.

    The main types of stunted seedlings are: first, waterlogging-induced stunted seedlings. Commonly seen in low-lying cotton field sections, prolonged overcast and rainy weather causes waterlogging-induced stunted seedlings, leading to blackened roots, grayish-green leaves, and slow growth. Second, drought-induced stunted seedlings. Mainly due to drought, the leaves turn yellow and dry red, there are few new roots, growth is extremely slow, and the proportion of red stems is large. Third, fertilizer-induced stunted seedlings. The main reason is that the base fertilizer is applied too shallowly, and the fertilizer comes into direct contact with the cotton seedling roots, causing concentrated fertilizer to damage the roots, manifested as darkened and reddened leaves, often accompanied by physiological disease spots, and thin, withered roots. Fourth, weak-quality stunted seedlings. Poor land preparation quality, rough transplanting, planting too deep or too shallow, and incomplete soil sealing cause this type of stunted seedling, resulting in small, thin, and weak seedlings that shrink and do not grow. Fifth, disease and pest-induced stunted seedlings. The damage from diseases and pests such as damping-off, anthracnose, fusarium wilt, thrips, and cotton aphids often causes holes or curling in cotton seedling leaves, yellowing and reddening of leaf color, few and thin roots, tight internodes, and short plants that appear as stunted seedlings.

    After stunted seedlings occur, the cause should be carefully identified and targeted prevention and control should be carried out. For stunted seedlings caused by waterlogging, drainage should be carried out to lower humidity and protect the roots, with high-standard opening of waist ditches, compartment ditches, and surrounding ditches to ensure that heavy rain in May and June drains quickly, lowering the groundwater level to below 60 cm, so that the field dries after the rain stops. Intertillage should also be carried out in time to disperse moisture, with deep hoeing between rows and shallow hoeing between plants, to increase temperature and supplement oxygen for the early growth of cotton seedlings.

    For stunted seedlings caused by early drought, the most effective method is watering. Alternate-row watering or spot watering by diverting water can be used. Never flood irrigate, as this suppresses the rise of soil temperature.

    For fertilizer-induced stunted seedlings, fertilization should be scientific to promote early growth. Base fertilizer should be reasonably matched and applied deeply. Generally, about 2500 kg of farmyard manure per mu, or 40-50 kg of compound fertilizer and 1.5 kg of boron fertilizer, can prevent and control nutrient-deficiency-type stunted seedlings. For cotton fields where obvious fertilizer-induced stunted seedlings occur, a shallow intertillage should be carried out once, one watering should be done on a sunny day, and then trace element fertilizers such as 0.1%-0.4% zinc sulfate and ferrous sulfate should be sprayed.

    For weak-quality stunted seedlings, the cotton field should be carefully prepared before transplanting cotton seedlings, formed into narrow compartments with deep ditches, fine soil and level ground, uniform soil fertility, and a structure that is loose on top and firm below, to prevent hanging-root-type stunted seedlings and provide a comfortable environment for the early growth of cotton seedlings. After transplanting, intertillage and earthing up should be carried out in time to promote root development. Combined with earthing up around the base, intertillage and loosening the soil should promote transformation. Intertillage should be shallow first and then deep, and earthing up around the roots should be low first and then high, carried out in stages, generally earthing up 8-10 cm. Fertilizer topdressing should also be combined, applying small amounts multiple times. Generally, 2-3 kg of urea per mu is applied with water, or 6-8 loads of dilute human and livestock manure water per mu can also be applied. Each topdressing should be carried out after intertillage.

    For stunted seedlings caused by diseases and pests, on the basis of good field investigation, the right remedy should be applied and prevention and control work should be done well. Urea can also be applied at 3-5 kg per mu, and 0.2%-0.3% potassium dihydrogen phosphate solution can be sprayed on the leaves 2-3 times to promote the early recovery of cotton seedlings and their early and rapid growth.