Cotton Wilt Disease and Its Prevention: A Technical Guide
Source: Seed Technology
Category: Technical Articles
Update Time: October 29, 2008, 4:20 PM
Reads: 69
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, leading to a steady expansion in planting areas. However, the spread of yellow wilt disease has become a serious challenge for maintaining high yields and stable production in cotton cultivation.
1. Symptoms of Cotton Wilt
Cotton yellowing disease is a vascular disease characterized by brown streaks on the stems.
1.1 Seedling Stage Symptoms
The disease can affect cotton plants during the seedling stage, with peak occurrences before and after budding. There are five main types of symptoms:
(1) Yellow Mesh Type: The cotyledons or true leaves turn pale green or yellow, showing a mesh-like pattern while remaining partially or fully green.
(2) Yellow Type: The cotyledons or true leaves turn yellow, sometimes with localized necrotic spots.
(3) Purple Type: The leaves turn reddish-purple or show erythematous discoloration, with purple veins, eventually leading to wilting and death.
(4) Blue and Dry Type: Leaves suddenly lose water, turning dark green, and appear blue and dry.
(5) Shrinkage Type: True leaves thicken and shrink, appearing dark green.
1.1.2 Adult Plant Symptoms
In adult plants, symptoms include yellowing, purpling, and bluing. Additionally, there is a dwarf type where the internodes shorten, the plant becomes stunted, leaves are thick and wrinkled, and many severely affected plants have withered leaves.
1.2 Verticillium Wilt Symptoms
Verticillium wilt typically does not show symptoms at the seedling stage but appears after bud formation. Initially, the middle and lower leaves develop light yellow irregular patches between the veins. Over time, these patches expand into brown, dry areas, while the main veins remain green, creating a mottled or watermelon rind-like appearance. During hot and dry periods, an acute wilting form may occur, with the main veins showing green to gray-green patches, as if burned by hot water, causing leaves to fall off.
2. Onset of Cotton Wilt Disease
Fusarium wilt usually begins in mid-May, peaking around late June when the cotton is in the budding stage. As temperatures rise, the disease activity decreases. A second peak often occurs in late August. Verticillium wilt generally starts during the budding stage, reaching its peak during flowering. Factors such as continuous cropping, low-lying fields, poor drainage, untreated seeds, and old cotton-growing regions contribute to higher disease incidence.
3. Control Measures for Verticillium Wilt
3.1 Selecting High-Yield and Disease-Resistant Varieties
New varieties with strong resistance, such as Zhongzhimian 2, have been developed to help reduce the impact of wilt diseases.
3.2 Agricultural Practices
3.2.1 Crop Rotation: Land with heavy infestations should be rotated for more than 7 years, while general rotation periods should be 3–4 years.
3.2.2 Balanced Fertilization: Applying phosphorus, potassium, and micronutrients helps promote healthy growth and enhance resistance to diseases.
3.2.3 Removal of Infected Plants: Diseased roots and soil should be removed and buried deeply during the seedling stage. Once the plants grow, diseased plants and debris should be pulled out, taken away, and burned to disinfect the soil.
3.3 Chemical Control
3.3.1 Seed Treatment: Soak 100 kg of seeds in 200 kg of water with 1 kg of 40% carbendazim suspension for 24 hours to control Verticillium wilt and seedling diseases.
3.3.2 Foliar Sprays: Applying fungicides and foliar fertilizers can help manage the spread of yellow wilt and improve plant resistance. Products like Greenhenge No. 1, 3, 4, 8, or NEB (En Yibi) from American Science and Technology are commonly used.
3.3.3 Application of Fulvic Acid Fertilizers: These fertilizers have a strong inhibitory effect on cotton wilting and can significantly reduce disease severity.
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