In recent weeks, we have visited cotton fields in Hebei, Shandong, Jiangsu, Hubei, and Henan. Since the emergence of this year’s cotton crop, the growing conditions have been challenging due to excessive rainfall, lower temperatures, reduced sunlight, and wind damage in certain areas. As a result, the growth of cotton seedlings has been slower than usual. According to field surveys conducted as of June 5, the average height of cotton seedlings was 4.4 cm shorter compared to the same period last year, with 1.8 fewer leaves per plant. The budding stage also started 5–7 days later than in previous years. Given these conditions, it is crucial to implement effective field management practices to ensure a successful harvest this season.
To address the current situation, we will discuss several key strategies tailored to local conditions:
1. **Current Growth Stage of Cotton**
Most cotton fields have now entered the bud stage, which marks the transition from vegetative to reproductive growth. However, vegetative growth still dominates at this point. The development of underground parts, such as roots, has accelerated significantly, with the main root growing 2–3 times faster than the above-ground portion. This is a critical period for root system development. Nutrient demand shifts during this phase—from nitrogen, which was dominant during the seedling stage, to increased needs for phosphorus and potassium. The budding period typically lasts 24–30 days, with Hebei’s usual start around early June. This year, the budding period has been delayed by about 5–10 days.
2. **Key Management Goals**
Given the impact of the current weather conditions on seedling quality, the focus should be on promoting the growth of weaker plants and increasing leaf area to support future yield potential. For high-yielding cotton varieties, maintaining steady growth while encouraging early flowering and multiple buds is essential. All actions should revolve around the principle of "steady growth" to maximize productivity.
3. **Current Field Management Practices**
(1) **Timely Cultivation**
This year, most regions do not require irrigation due to sufficient rainfall. However, proper cultivation is still necessary. Weaker fields should be cultivated more frequently—every 7–8 days—and thoroughly. High-yield fields should be cultivated earlier and more deeply, with a depth of at least 8 cm. On dry land, shallow cultivation is preferred to avoid root damage. In waterlogged areas, deep plowing can help control root growth and prevent premature aging. Late-season cultivation should not be too deep to avoid harming the plants.
(2) **Fertilization Based on Need**
Fertilizer application should be adjusted based on field conditions. For lush, well-fertilized fields, reduce or eliminate nitrogen fertilizer and apply 5 kg of diammonium phosphate per mu. For weak seedlings or under-fertilized fields, apply 12.5 kg of urea and 5 kg of potassium per mu, along with foliar sprays of 2% urea and 0.3% potassium dihydrogen phosphate. Avoid overuse of nitrogen to prevent excessive vegetative growth and bud drop.
(3) **Soil Uncovering After Film Removal**
In northern regions, it's best to remove plastic mulch in late June, after the peak of the Lei period, to promote root development and improve soil aeration. After removal, cultivate the soil promptly to enhance drought resistance. In southern regions, drainage ditches should be dug to prevent waterlogging.
(4) **Pruning Practices**
Pruning should be done scientifically, including removing leaves, pinching back buds, and cutting off wild pods. This should be delayed slightly, ideally when 3–4 fruit branches are visible. This helps strengthen weak seedlings and improves overall plant structure. For vigorous fields, remove lower leaves on the main stem to encourage better light penetration.
(5) **Growth Regulation**
Spraying with growth regulators like mepiquat chloride can help control excessive growth. Apply at a concentration of 30–50 ppm (about 0.4–0.75 grams per 30 liters of water), with 0.3–0.8 grams per mu. The optimal time is during the Sheng Lei period, when four fruit branches are visible. Fields with good growth may need more frequent applications, while weak or dry fields should receive less or no spray. If plant height exceeds 40 cm, increase the dosage to 2 grams per mu.
(6) **Pest Control**
Major pests include bollworms, aphids, spider mites, and weevils. For bollworms, a combination of malathion and phoxim is effective and cost-efficient. Acetamiprid works well for aphid control, and a mixture of acetamiprid and imidacloprid can be used if resistance develops. Spider mites respond well to avermectin-based products. For bollworms, options like chlorpyrifos, acephate, and other insecticides are available.
**Disease Management**
Wilt disease remains a concern during the budding stage. Although the incidence was low early this year, it tends to peak in mid-to-late June. Strengthening field management, improving pesticide application, and enhancing plant resistance are essential to prevent outbreaks.
By implementing these targeted measures, farmers can overcome the challenges posed by adverse weather and ensure a productive and healthy cotton crop this season.
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