Investing in high-quality cotton seed and planting under favorable conditions sets the stage for a strong cotton stand. But when cotton seedlings begin to collapse from damping-off shortly after planting, that investment can disappear quickly.
Early season cotton diseases are a common challenge for many cotton growers. Understanding what to look for and how to reduce risk before planting can help protect stand establishment and prevent damping-off before it starts.
Identifying cotton seedling diseases
Several soilborne pathogens can infect cotton seedlings as they emerge and begin early growth. When disease develops, it often appears as damping-off, root rot or stem lesions that weaken or kill young plants.
Early scouting can help you diagnose disease in cotton and determine whether plant stands remain adequate. Identifying the likely pathogen can also provide clues about the conditions that favor cotton disease development and help guide prevention strategies in future seasons.
For example, Rhizoctonia solani, often called sore shin, commonly produces sunken reddish-brown lesions on the plant’s hypocotyl near the soil line. These lesions can girdle the stem and cause cotton seedlings to collapse after emergence.¹
Pythium species frequently cause seed rot before emergence or damping-off shortly after seedlings appear. Infected plants often have soft, water-soaked roots and may appear weak, stunted or chlorotic.²
Fusarium species can cause a cotton blight disease characterized by yellowing, wilting and stunted growth, often accompanied by brown discoloration in roots or vascular tissue.
Another cotton disease, black root rot, caused by Thielaviopsis basicola, produces blackened roots and hypocotyls. Affected plants typically have reduced taproot diameter and poor vigor.³
Environmental risk factors and optimal planting conditions
Environmental conditions at planting can strongly influence the risk of cotton seedling diseases. Soilborne pathogens such as Pythium, Rhizoctonia and Fusarium are more likely to infect cotton seedlings when germination and emergence are slowed by stress. Cold or overly wet soils delay cotton seedling growth and give these pathogens more time to attack young plants. Poor drainage and saturated soils also favor diseases like Pythium, which can cause seed rot and damping-off before or shortly after cotton seedlings emerge.⁴
Planting when soil temperatures are consistently around 65 F or higher can help reduce cotton disease risk. Warm, well-drained soils allow seeds to germinate quickly and support stronger early root growth. Faster emergence helps cotton seedlings outgrow early pathogen pressure. Avoiding soil compaction, reducing crusting after planting and selecting favorable planting windows can also improve stand establishment and reduce disease risk.
Proactive cotton disease control and seed treatments
Preventing cotton diseases needs to start before you plant. Because these pathogens live in the soil, if emergence is delayed by cold or saturated soils, cotton seedlings remain vulnerable to infection for longer periods and disease pressure increases.⁵
Using high-quality seed and planting into warm, well-drained soils reduces early stress and allows seedlings to establish faster, limiting the window when pathogens can infect young plants.⁶
Fungicide seed treatments are another important tool for protecting seedlings during this early growth stage. Many cotton seeds are treated with fungicides that protect against pathogens such as Pythium, Rhizoctonia and other soilborne organisms that cause damping-off and seedling blight. These treatments help protect the seed and emerging roots during the first weeks after planting, when seedlings are most susceptible to infection.
In-season scouting and cultural mitigation of cotton seedling diseases
Scouting early and consistently can help you catch these symptoms and determine whether your stands will get established adequately. Most cotton seedling diseases appear within the first 30 days, when young plants are most vulnerable to soilborne pathogens.⁷
As you scout, look for symptoms such as damping-off, root rot or stem lesions that can weaken seedlings or reduce stand counts.
If you find infected plants, your management options this season may be limited. Once pathogens infect cotton seedlings, fungicide applications after emergence generally provide little benefit.⁸ Instead, focus on evaluating plant populations to determine whether the remaining stand is sufficient or if replanting may be necessary.
Cotton seedling diseases can threaten stand establishment, but many of the most effective management decisions are made before problems arise. By planting into favorable conditions, protecting seed with treatments and scouting fields early, you can reduce disease risk and give your cotton crop the strongest possible start.
Experts are available to help you make your cotton seed treatment decisions. Reach out to your seed retailer, a nearby extension office agent or a seed company professional like your regional BASF representative.
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Endnotes
- Cotton Incorporated. “Cotton Seedling Disease Identification.” Cotton Incorporated, National Cotton Council, https://www.cotton.org/tech/pest/seedling/identification.cfm
- Cotton Incorporated. “Cotton Seedling Disease Identification.”
- Davis, R. M. “Seedling Diseases.” UC IPM Pest Management Guidelines: Cotton, University of California Agriculture and Natural Resources, https://ipm.ucanr.edu/agriculture/cotton/seedling-diseases
- Ahumada, Daisy. “Cotton Seedling Diseases.” NC State Extension Publications, North Carolina State University Extension, 29 Sept. 2023, https://content.ces.ncsu.edu/cotton-seedling-diseases
- Hu, Jiahuai, and Randy Norton. Symptom Identification and Management of Cotton Seedling Diseases. University of Arizona Cooperative Extension, Oct. 2020, https://acis.cals.arizona.edu/docs/default-source/agricultural-ipm-documents/cotton/az1856-2020.pdf
- Ahumada. “Cotton Seedling Diseases.”
- Ahumada. “Cotton Seedling Diseases.”
- Davis, R. M. “Seedling Diseases.”
