The Incidence and Control of Cotton Verticillium Wilt
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Cotton Wilt Disease and Its Prevention: A Technical Guide
Source: Seed Technology
Category: Technical Articles
Update Time: October 29, 2008, 16:20:29
Reads: 59 times
Authors: Li Guorui, Zhang Gang, Cui Yingshu, Ren Yongxia (Kuantao County Bureau of Agriculture)
Cotton is a major economic crop that has seen increasing profitability with the development of the market. As a result, the area under cotton cultivation has expanded significantly. However, the rapid spread of yellow wilt disease has become a serious threat to the sustainable high yield and stable production of cotton. This article provides an in-depth analysis of the symptoms, causes, and control measures for cotton wilt disease.
**1. Symptoms of Cotton Wilt Disease**
Cotton yellowing disease is a vascular disease that affects the plant's internal structure, causing brown streaks on the stems.
**1.1 Symptoms at the Seedling Stage**
Yellow wilt disease can occur during the seedling stage, with peak incidence occurring before and after budding. There are five distinct types of symptoms:
- **Yellow Mesh Type**: The cotyledons or true leaves turn yellow with a mesh-like pattern while remaining green in some areas.
- **Yellow Type**: Leaves turn yellow, sometimes with localized dead spots.
- **Purple Type**: Leaves take on a reddish-purple color, with purple veins, leading to gradual wilting and death.
- **Blue and Dry Type**: Leaves lose water quickly, turning dark green and appearing blue and dry.
- **Shrinkage Type**: True leaves thicken and shrink, appearing dark green.
**1.2 Symptoms in Adult Plants**
In mature plants, additional symptoms include the **dwarf type**, characterized by shortened internodes, bent stems, thick and wrinkled leaves, and significant leaf drop.
**1.3 Verticillium Wilt Symptoms**
Verticillium wilt typically does not show symptoms at the seedling stage but becomes apparent after bud formation. Initially, the middle and lower leaves display light yellow, irregular patches between the veins. These patches gradually expand into brown, dry areas, while the main veins remain green, creating a mottled or "watermelon rind" appearance. During periods of drought followed by heavy rain, an acute wilting form may appear, with leaves showing burn-like damage and falling off rapidly.
**2. Onset of Cotton Wilt Disease**
Fusarium wilt usually begins in mid-May, with the peak occurring in late June during the budding stage. As temperatures rise, the disease tends to subside. A second peak often occurs in late August. Verticillium wilt typically appears during the budding phase, with the flowering period being its most severe stage. Factors such as continuous cropping, poor drainage, low-lying fields, untreated seeds, and previous infestations in old cotton regions contribute to higher disease incidence.
**3. Control Measures for Verticillium Wilt**
**3.1 Selecting Resistant Varieties**
The development of new, disease-resistant cotton varieties has provided an effective solution. Examples include Zhongzhimian 2 and others that show strong resistance to wilt diseases.
**3.2 Agricultural Practices**
- **Crop Rotation**: Land affected by the disease should be rotated for at least 3–4 years, with severely infected land requiring more than 7 years of rotation.
- **Balanced Fertilization**: Proper use of phosphorus, potassium, and micronutrients helps strengthen seedlings and improve plant resistance.
- **Removal of Diseased Plants**: In the early growth stages, diseased roots and soil should be removed and buried deeply. Later, diseased plants and debris should be pulled out, taken from the field, and burned to prevent further spread.
**3.3 Chemical Control**
- **Seed Treatment**: Soaking 100 kg of seeds in 200 kg of water with 1 kg of 40% carbendazim suspension for 24 hours effectively controls Verticillium wilt and seedling diseases.
- **Fungicide Spraying**: Applying fungicides like Greenhenge No. 1, No. 3, No. 4, No. 8, or high-resistance NEB (En Yibi) from American Science and Technology can help manage the disease and boost plant immunity.
- **Fulvic Acid Fertilizers**: These fertilizers have a strong inhibitory effect on wilting and can improve plant health.
By implementing these integrated management strategies, farmers can significantly reduce the impact of cotton wilt disease and ensure more stable and productive cotton farming.