Damping-off seedling disease prevalent due to cooler weather

(04/20/20) BATON ROUGE, La. — Cool, damp conditions are affecting some seedlings that are trying to develop a stand.

Damping-off results when seedlings die soon after they emerge. This type of disease is caused by a variety of soil-inhabiting fungi, such as Fusarium and Rhizoctonia, and water molds, such as Phytophthora and Pythium.

LSU AgCenter plant doctor Raj Singh said the disease caused by Fusarium and Rhizoctonia species generally occurs under warm and dry conditions, whereas Phytophthora and Pythium prefer cold, wet soils.

The disease may also occur when seeds are planted too early in spring or too deep or when old seeds are used. The disease can occur on vegetables as well as annual ornamental plants.

“Seedlings affected by damping-off exhibit dark lesion on their stems at the soil line,” Singh said. “Stems at the soil line rot, and seedlings fall over.”

As the disease develops, roots rot and water and nutrient uptake is interrupted. In some cases, bark easily sloughs off on the lower stem where rotting occurred. Affected seedlings eventually die.

“Management of damping-off seedling disease requires an integrated disease management approach,” he said.

Good cultural practices — including proper soil preparation, use of raised beds to provide adequate water drainage, proper planting depth and plant spacing, and planting in fertile soils with proper soil pH — play key roles in growing healthy seedlings.

“Avoid sowing seeds or transplanting seedlings in cool, wet soils,” Singh said. “Overwatering before or during the germination process may adversely affect seedling stand.”

Using fungicide-treated seeds or transplants also may be beneficial, he said.

Fungicides labeled for damping-off seedling disease are available and may be used preventatively where disease is prevalent.

More information on fungicide use is available online in the Louisiana Plant Disease Management Guide at www.LSUAgCenter.com.

Bell pepper plant wilting due to damping-off seedling disease.

A bell pepper plant exhibits wilting due to damping-off seedling disease. Photo by Stuart Gauthier/LSU AgCenter

Rotting okra seedling.

Rotting and sloughing off of the lower stem of an okra seedling is caused by damping-off disease. Photo by Stuart Gauthier/LSU AgCenter

Fallen over okra seedling.

A fallen over okra seedling is affected by damping-off seedling disease. Photo by Stuart Gauthier/LSU AgCenter

4/20/2020 8:40:04 PM
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