Seed decay and seedling blight of corn
Many pathogens cause seed decay and seedling blight such as Pythium, Fusarium, Diplodia, Rhizoctonia, and Penicillium spp. The first symptom may be an area of the field with poor or no stand. Decayed seeds are very soft and may be covered with fuzzy fungal growth; seeds can be difficult to find if badly rotted. Postemergence damping off appears as yellowing and wilting; seedlings soon collapse leaving only dead leaves above the soil. Nodal roots may show the same decay symptoms as seminal roots and the mesocotyl. If the nodal root system escapes decay, the plant will survive; it may be stunted or recover fully.
Favored by cool, wet soils, these diseases are more common in low-lying or poorly drained areas or in fields planted too early in spring.
Standard seed treatment fungicides on corn reduce risk of seed decay and seedling blights. Planting corn when the soil temperature is above 50°F and soil moisture is not excessive also may reduce risk. Damping off of corn plants from seedling disease. Image: A. Robertson
Aboveground stunting caused by Pythium infection. Image: A. Robertson