What causes stunted cotton seedlings? A detailed explanation of prevention and control methods

During the transplanting period, cotton is often affected by abnormal weather, weak seedlings, inadequate cultivation measures and other factors, which cause a long slow-seedling period and stunted growth after transplanting, delaying the cotton's growth process and reducing cotton yield. The causes of stunted cotton seedlings and their prevention and control are described below:

1. Causes

1. Poor cotton seedling quality. ① Insufficient fertilization of the seedbed produces small, weak seedlings with poor growth vigor that establish slowly. ② Improper seedbed management produces leggy seedlings or overgrown seedlings, which lose too much water after transplanting and suffer severe transplanting injury.

2. Unsuitable temperature. In many places the temperature in early May is still unstable, and cotton transplanted early often suffers cold damage from low-temperature cold waves, with growth inhibited. When late-crop cotton is transplanted, the high temperature and large evaporation cause severe transplanting injury to the seedlings and a long slow-seedling period.

3. Rushed transplanting on rainy days. In some places cotton is transplanted after wheat. @#@245@#@After harvest, the time for transplanting cotton is tight, and some cotton farmers, to reduce the labor of watering at transplanting, rush to transplant on rainy days. Because the soil is wet, human trampling destroys the soil structure, and when the mud dries it becomes severely compacted, making it hard for the cotton seedling roots to penetrate downward. In some fields, prolonged waterlogging, low soil temperature and poor soil aeration reduce the roots' ability to absorb water and nutrients, thereby inhibiting cotton growth.

4. Drought and water loss. If no water or insufficient water is given at transplanting, and this is followed by continuous drought, soil moisture becomes severely deficient, the old roots are damaged, new roots cannot emerge, the upper part of the cotton plant wilts, and growth is inhibited, forming small, old seedlings.

5. Improper application of base fertilizer. Some cotton farmers are accustomed to using a hole-opening tool to make planting holes and applying the base fertilizer directly into the holes before transplanting the cotton, which brings the cotton seedling roots into direct contact with the chemical fertilizer and causes fertilizer burn. The cotton seedling roots are injured and the lower leaves drop off.

6. Damage from diseases and pests. If pesticides are not applied in the seedbed in time, cotton seedlings suffer damage from red spider mites, cotton aphids, thrips, damping-off disease, anthracnose and other diseases and pests and cannot grow normally.

2. Prevention and control methods

1. Cultivate strong seedlings. To cultivate strong seedlings, attention should be paid to fertilizing the pot soil, choosing large pots (pot diameter above 7cm), ensuring full stands with high temperature and high humidity, regulating temperature and fertilizer to raise strong seedlings, and hardening off healthy seedlings before transplanting.

2. Transplant at the appropriate time. Transplant at the appropriate time according to the weather, seedling condition and crop rotation situation. For early-crop cotton, to avoid the effects of low-temperature cold waves on cotton, transplant on a sunny day once the 5cm soil temperature is stable above 16°C, and do not transplant June cotton. For cotton after wheat or rapeseed, clear the stubble early and rush to transplant, doing so as the crop is harvested, and strive to finish transplanting by early June.

3. Cover with plastic film. Covering with plastic film to increase temperature and retain moisture is an important measure to prevent low-temperature stunting in cotton and promote early growth, and it is especially important for early-transplanted cotton. Before transplanting cotton, open a furrow between the small rows and apply the settling-in fertilizer well: nitrogen fertilizer at 20%-25% of the total fertilizer application, potassium fertilizer at 50%-60% of the total fertilizer amount, and all of the phosphorus fertilizer. After rain or after creating soil moisture, cover with plastic film. At transplanting, punch holes in the film; this not only allows earlier transplanting and eliminates fertilizer damage, but also preserves moisture and raises soil temperature.

4. Improve transplanting quality. ① Transplant on a sunny day; do not rush to transplant on rainy days. ② At transplanting, firm the pot soil to ensure the pot body merges with the soil, and do not transplant "hanging-foot seedlings." ③ Open the hole, lift the pot, place the pot, firm the soil and water in the same sequence, and water thoroughly; do not transplant diseased, thin, overgrown or broken-pot damaged seedlings, and transplant large and small seedlings separately. ④ Change the practice of applying base fertilizer in the holes to broadcast application throughout the layer: about 7 days before transplanting cotton, spread the settling-in fertilizer evenly along the cotton rows on the topsoil, then plow and level the land.

5. Strengthen post-transplant management. ① Carry out intertillage and loosening of the soil to break up soil compaction, which can increase temperature and aeration, promote cotton seedling root growth, and enhance the seedlings' ability to absorb fertilizer and water. ② For fields with insufficient base fertilizer, drought and water shortage, or thin cotton seedlings that grow slowly after transplanting, apply a small amount of fertilizer and irrigate heavily in time (generally about 15kg of ammonium bicarbonate per 667 sq m), or spray foliar fertilizer to help the cotton seedlings resume growth as quickly as possible. ③ Do a good job of controlling diseases and pests at the seedling stage.