Cotton Planting Tips in the Malvaceae Family and How to Cope with Rain During the Seedling Emergence Stage

Cotton belongs to the Malvaceae family. Grown in tropical regions, it can reach 6 m in height, though it is generally 1 to 2 m. The flowers are milky white, and shortly after blooming they turn dark red and then wither, leaving behind small green capsules called cotton bolls. So what should be noted when planting cotton? What should be done if rain falls during the cotton seedling emergence stage?

I. What should be noted when planting cotton

1. Thinning seedlings at the right time

A seedling-infested field is worse than a weed-infested one. Timely thinning prevents the appearance of leggy seedlings and promptly resolves the competition among cotton seedlings for space, nutrients, light and water, while also making timely intertillage and pest control easier. It plays a very good role in promoting root growth of cotton seedlings, preventing seedling death and encouraging early development. Generally, cotton should be thinned when it has grown 1 true leaf. In drill-sown cotton fields, a bamboo pole marked with the standard plant spacing can be used to thin the seedlings in one pass, keeping uniform, vigorous seedlings. In saline-alkali land, thinning can be postponed until the two-to-three-true-leaf stage.

2. Intertillage early

Intertillage loosens the soil, raises soil temperature, eliminates weeds, promotes water movement and aeration, accelerates the decomposition of soil nutrients, and prevents and reduces the occurrence of cotton seedling diseases. It is one of the main measures for achieving strong seedlings and early development in cotton. The effect is especially striking in open-field, direct-sown cotton fields where the soil is too wet, the soil temperature is low and the soil is compacted. The frequency and depth of intertillage should be appropriate, so as to achieve soil that is not compacted and a field free of weeds. Generally, intertillage is carried out 2 to 3 times; it is shallow around the cotton seedlings and can reach 7 to 10 cm deep between the rows.

3. Controlling diseases and insect pests

Diseases. Seedling-stage diseases are the main obstacle affecting full and strong stands of cotton. There are ten diseases that harm cotton roots, among which are those causing root rot, bud rot and stem-base rot, followed by root rot; diseases mainly harming the cotyledons, true leaves and stems include stem blight, angular leaf spot, leaf spot and soft rot. But those with the greatest impact on cotton development are: damping-off, anthracnose and red rot. They can cause disease before the cotton seedlings emerge, leading to seed rot, bud rot and root decay. In mild cases they affect the growth and development of cotton seedlings; in severe cases they cause massive seedling death during the seedling stage, resulting in serious gaps in the stand and broken rows, and in the worst cases the entire field is destroyed. Control methods: rational crop rotation, fine land preparation, balanced fertilization, increased application of organic fertilizer or biological antagonistic bacterial fertilizer, use of coated seeds, continuous sun exposure for 2 to 3 days before sowing, and appropriately late sowing to improve sowing quality. At the seedling stage, drench the roots with 200-fold 80% Tuzet, or 50% carbendazim, or 70% thiophanate-methyl, or Tanteling, or gentamicin. For controlling cotton red rot at the boll stage, spray with 500-fold 50% carbendazim or 800-fold 70% mancozeb.

Insect pests. The main pests at the cotton seedling stage are cotton aphid, cotton spider mite, cotton thrips and cutworm. With the spread of transgenic insect-resistant cotton, wheat-cotton intercropping and the expansion of cotton fields using delinted coated cotton seed, the number of natural enemies of cotton pests has increased, and the types of cotton pests and the degree of damage have also changed greatly. Therefore, in controlling cotton seedling-stage pests, attention should be paid to protecting and utilizing natural enemies, distinguishing different types of cotton fields, and carrying out pest forecasting and control separately. The control of cotton seedling-stage pests focuses on the cotton aphid: first treat the seed with 3% carbofuran granules, then after emergence control with omethoate.

4. Appropriate topdressing and controlled watering

Fertilization. The water requirement of cotton at the seedling stage accounts for only 5% of its total nutrient requirement over its life, so in cotton fields with sufficient base fertilizer and in high-yield cotton fields, no topdressing is generally applied. However, for cotton fields with poorer soil fertility and a small amount of base fertilizer, the seedling-promoting fertilizer should be applied early; topdressing at the seedling stage is mainly based on quick-acting nitrogen fertilizer and decomposed organic fertilizer. Generally, about 5 kg of standard nitrogen fertilizer per mu is sufficient.

Watering. Cotton needs little water at the seedling stage; to encourage the cotton roots to grow downward and the cotton plants to be stocky, in cotton fields with good pre-planting soil moisture, watering is generally not needed, and the first watering should be delayed as much as possible to avoid lowering soil temperature, causing seedling diseases and resulting in weak, late-developing seedlings. If the maximum water-holding capacity of the soil in the 10 to 40 cm layer falls below 50 to 55%, water promptly. When watering at the seedling stage, the amount should be small; use furrow irrigation or alternate-furrow irrigation, and carry out intertillage promptly after watering to break up compaction.

II. What to do if rain falls during the cotton seedling emergence stage

Remedial measures: (1) With trace rainfall, surface runoff and crusting generally do not form after the rain, so no crust-breaking treatment is needed; the cotton seed can rely entirely on its own energy for germination and growth to emerge normally. (2) With light rainfall, slight crusting of the soil covering the sowing holes occurs after the rain. If the rain falls within 3 days before or after sowing, after the rain dries, a homemade wooden or iron roller with spike teeth can be used for light rolling to break the crust; if the rain falls 5 to 6 days after sowing, after the rain dries, a homemade wooden or iron roller with ridges can be used for light rolling to break the crust; if the rain falls more than 7 days after sowing, only manual seedling release can be used to break the crust so as to avoid damaging the sprouting seedlings. (3) In cotton fields with lighter-textured sandy soil or sandy loam, which have good water permeability and a crust layer of limited hardness, once the soil covering the film is slightly dry and faintly moist, light rolling can be used to break the hard shell on the film. (4) In cotton fields with heavier-textured clay loam, when rainfall is relatively heavy, the soil at the sowing site has already had its loose state destroyed due to the greater degree of waterlogging; rolling too early or too heavily will aggravate soil crusting and is unfavorable for cotton seedling emergence. When the surface soil is slightly dry, manual loosening of the surface layer and the soil near the seeds can be used to break the crust and help the seedlings emerge. When cotton encounters rain, growers need to do a good job of intertillage and keep the soil loose and well drained so that cotton seeds can germinate better.