Verticillium wilt is one of the most destructive diseases affecting cotton production. Often referred to as "cancer" by farmers, it can cause severe damage to crops and significantly reduce yield and quality. With recent heavy rainfall and high humidity in the city, conditions are now favorable for the spread of *Verticillium dahliae*, the pathogen responsible for this disease. Field surveys have shown that some strains have already been detected in cotton fields. In Xinyi block, the disease has appeared lightly, while heavily infested areas have seen more severe outbreaks. Cotton fields with vigorous growth tend to show milder symptoms, whereas weaker plants suffer more. Based on past experience, Verticillium wilt has a major impact on cotton yields, often reducing production by 10% to 30%, and in severe cases, over 80%. In extreme situations, entire fields may need to be abandoned. This has prompted farmers to pay closer attention to the disease and take preventive measures.
**Identification of Cotton Verticillium Wilt**
*Verticillium dahliae* can infect cotton throughout its entire growth cycle. The disease typically appears about one month after sowing. Due to variations in cotton varieties, pathogen virulence, and environmental factors, the symptoms can differ widely.
**Seedling Stage:**
At this stage, the leaf edges become soft and appear water-damaged, with irregular pale yellow spots forming between the veins. These spots gradually turn brown and dry, and the vascular bundles inside the stems become discolored. In some cases, the seedlings look normal, but when cut open, dark brown discoloration can be seen in the xylem and vascular bundles.
**Adult Stage:**
The disease becomes more apparent during the budding phase, with symptoms intensifying in late June. By July and August, the disease reaches its peak. Symptoms vary, including yellowing between the veins, curling of leaf edges, and purplish-red dehydration spots. In some cases, leaves may fall off completely, leaving bare stalks. During drought or heavy rain periods in summer, acute symptoms may appear, such as sudden wilting and leaf drop. Some plants may not show stunting but still exhibit yellowing, while others may become dwarfed or even die.
**Pathogenesis, Transmission, and Disease Conditions**
**Transmission Routes:**
*Verticillium dahliae* spreads through various means. Infected seeds, plant residues, and compost can introduce the pathogen into new fields. Water runoff, agricultural tools, and soil movement also contribute to its spread. Once introduced, the pathogen can survive in the soil for up to 20–25 years, making it difficult to control. Heavy rains can accelerate its spread if no preventive measures are taken.
**Disease Conditions:**
The optimal temperature for disease development is between 22°C and 25°C. At higher temperatures (above 30°C), symptoms may slow down or temporarily disappear. The disease is most active during the budding and boll-forming stages. Resistant cotton varieties can help reduce the impact, but continuous cropping and excessive nitrogen fertilization increase the risk of infection.
**Comprehensive Control Measures**
1. **Plant Resistant Varieties:** Choosing resistant cotton varieties is the most cost-effective and efficient way to manage Verticillium wilt.
2. **Crop Rotation:** Rotating cotton with non-host crops for 3–5 years helps reduce pathogen buildup in the soil.
3. **Field Management:** Keeping fields clean, draining excess water, and maintaining balanced fertilization can prevent disease development. Organic manure and potassium-based fertilizers promote strong plant growth and improve resistance.
4. **Chemical Treatment:** Soil disinfection before planting using products like quintozene or Libenjing is effective. During the seedling stage, spraying fungicides like mancozeb or allicin can prevent infection. For more severe cases, repeated treatments and removal of infected plants are necessary to break the disease cycle.
By implementing these strategies, farmers can significantly reduce the impact of Verticillium wilt and protect their cotton crops.
Upper Limb External Fixation
The wrist joint external fixation fully considers the physiological characteristics of the wrist joint and the structural stability of the biomechanics, so that the metacarpophalangeal joint can be completely bent freely, and the tendons and ligaments of the fingers and wrists can be relatively relaxed. Moreover, the insertion method, length and stress of the bone traction needle are also considered, and the overall force of the bone traction needle is relatively uniform.
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