Latest Technical Methods and Tutorial for Cotton Seedling Stage Management
Cotton is one of the world's most important crops. To achieve high yields in cotton cultivation, good planting is the foundation and good management is the key. Management should focus on preserving full stands, preventing seedling diseases, promoting strong seedlings, and strengthening field management, laying a solid foundation for early budding and abundant budding. The cotton seedling stage refers to the period from emergence to budding, during which growth is mainly vegetative, that is, the growth of roots, stems, and leaves. The main goal is to ensure a full stand, achieve strong seedlings with early development, and lay the foundation for high yield.
Ensuring a Full Stand
Where seedlings are missing, measures should be taken as early as possible. Reserve seedlings sown at the same time should be transplanted into the gaps as early as possible. The earlier the transplanting, the shorter the recovery period, the faster normal growth resumes, and the more the difference from other seedlings can be reduced. When there are no reserve seedlings, surplus seedlings from between rows should be transplanted as early as possible. If no reserve seedlings were planted, there are no surplus seedlings between rows, and many seedlings are missing, replanting should be done as early as possible. Transplanting or replanting into gaps should be appropriately sparse, following the principle of filling 1 for every 2 missing, 2 for every 3 missing, and 3 for every 4 missing.
Intertillage and Soil Loosening
Early intertillage and soil loosening in open-field rows can promptly eliminate compaction caused by machinery traffic and foot traffic during sowing, reduce soil moisture to lessen seedling-stage diseases, and raise soil temperature to promote early cotton seedling development. After each rainfall, intertillage and soil loosening should be carried out in a timely manner so that the loose soil layer remains loose, and soil temperature, air, moisture, and nutrients are better regulated, promoting fast root growth, deep penetration, and wide distribution, forming a well-developed root system, enhancing the ability to absorb water and nutrients and resist adverse external conditions, and achieving strong seedlings with early development. The intertillage depth for open-field rows should be 8-10 cm. Intertillage should not be too frequent; it is sufficient to keep the ground free of weeds, uncompacted, and the surface soil relatively loose.
Early Disease Prevention
Diseases that occur in cotton before budding are collectively called seedling-stage diseases. During this period, the nutritional area is relatively small and the root system is not yet well developed. When encountering low-temperature and rainy weather, pathogens can easily infect the plants. In mild cases, cotton seedlings grow weak and small; in severe cases, large areas of seedling death occur. Based on incidence patterns, damping-off, anthracnose, and red rot are the most prominent. These diseases occur early, spread quickly, and cause severe damage, so they must be prevented with great attention. In preventing seedling diseases, emphasis must be placed on the word “early” and the word “prevention.” So-called early means spraying before disease occurs. Putting “prevention” first means preventing disease without seeing disease; only with preventive awareness can initiative be shown in the “early” aspect. If treatment is delayed until disease is visible, it will increase control costs, require more labor, produce more weak seedlings, lead to premature senescence, and affect final yield. Spray no fewer than two times before three true leaves appear. The first is at full emergence, spraying 80% ethylicin diluted to a 2000-fold solution. The second is during the 1-2 true leaf stage, spraying 70% hymexazol at a 3500-fold solution. When temperature changes greatly, spray agents that nourish and strengthen seedlings, such as Tianfengsu, Shuofeng 481, Fengshousu, Tianda 2116 Zhuangmiaoling, Fushenzhuang, and others.
Early Pest Control
Pests during the cotton seedling stage are relatively severe. Different damage times and damage modes bring greater impacts on cotton seedling growth and also create certain difficulties for field control. Some pests transmit viruses, some affect cotton growth and delay development, and some cause loss of growing points, turning plants into male cotton or breaking stems to form headless plants. For cotton aphids, small thrips, mirids, and red spider mites, spray 50% pirimicarb wettable powder at a 1000-fold solution or 10% imidacloprid at a 2000-fold solution for control. For young larvae of cutworms, spray 20% fenvalerate at a 1500-2000-fold solution or 50% phoxim at a 1500-fold solution. For older cutworm larvae, use the toxic bait method: mix 5 kg of roasted wheat bran or cottonseed meal with 50 mL of 50% phoxim added to 1 kg of water, spray and mix evenly, and scatter between rows in the evening.
Eliminating Large and Small Seedling Differences
As the saying goes, large seedlings bully small seedlings, and small seedlings do not set bolls. This means that large seedlings have a larger form and a stronger advantage in competing for light and nutrients, while weak seedlings are at a disadvantage and become more passive under inferior conditions, and the gap between the two widens. Such a population structure will not produce ideal yields. Therefore, in cotton field management, action should be taken early to apply supplemental fertilizer to small seedlings, using a 0.5-1.0% urea aqueous solution for root drenching (use lower concentration when seedlings are smaller). The method is to put the solution into a sprayer, remove the nozzle, and let it flow along the plant. About 150-200 mL of solution per plant is sufficient.