Seedling Blights Are a Concern for Which Crops?

Definition

• Seedling blight is a fungal infection in the soil most commonly caused by Pythium, Fusarium, Diplodia, Rhizoctonia and Penicillium.

  These fungus infections are common in soils throughout the U.S. crop-growing areas.

  Seedling blight, also known as damping off, is what causes the seed and emerging seedling to rot and die.

  Conditions like poor weather that prevent seeds from emerging and growing give these soil fungi more time to attack the seed and developing plant.

Weather

• A cold, wet spring will make seeds slow to germinate. This increases the chances of seedling blight occurring either in the seeds or in the newly developing plant.

  Crops that are planted too early tend to be susceptible to seedling blight. Corn that is planted in April or in early May will be more susceptible to blight and tend to show damage.

  The fungi that cause seedling blight varies depending on the weather. Some, like Pythium, like cool wet weather, while the fungus Rhizoctonia prefers a cool, dry spring to flourish.

Symptoms of Blight

• Patches in the field will show where the seed has failed to germinate. The seeds that have not germinated will show evidence of root rot -- they will be discolored and soft and may have fungi growing all over them. Seeds that have just started to germinate will be discolored and also have a wet, rotted appearance.

  Corn seeds that have germinated through the soil surface will tend to be yellowy, wilt and die. There will be discolored, sunken lesions on the mesocotyl -- the part of the young plant that lies between the seed (which remains buried) and the plumule, which gives rise to the first true leaves.

Treating Seeds to Prevent Blight

• Treating seeds before planting can help prevent seedling blight from occurring by protecting the seed and the newly emerged seedling.

  Seeds should be planted shallowly, instead of deep, so the seedling does not have to rely on the nutrients from the seed for very long.

  A good quality seed should also be planted, as this prevents fungi from attacking cracked seeds, which leads to decay.