By Louis Sutton
Regional Product Manager (West) and Agronomy Lead

During the spring planting season, farmers need to watch for several diseases that can affect corn and soybean seedlings. Below we will explore some of the most common emergence diseases.

Corn Diseases

The first symptom of diseases like Pythium, Fusarium, and Rhizoctonia may appear as an area with poor or no stand in a recently emerged field. If you dig for seeds in these rows, watch for these symptoms of decayed seeds: very soft and covered with fuzzy fungal growth. It can be difficult to locate badly rotted seeds. These diseases are favored by cool, wet soils and are commonly found in low-lying or poorly drained areas. These diseases are also common in fields planted too early, so make sure you are planting into fit soil conditions (temperature, seed bed, depth) and protecting your seed with a premium treatment package.

Pythium seedling blight symptoms. (Photo courtesy of Crop Protection Network)

Aboveground stunting caused by Pythium infection. (Photo by A. Robertson)

Pythium seedling blight: This disease is caused by the soil-borne fungus Pythium, which thrives in wet soils. It can cause seed rot, seedling damping-off, and root decay.

Fusarium seedling blight: This is another soil-borne fungal disease that can affect corn seedlings, causing seed rot and seedling damping-off. It is also favored by cool, wet conditions.

Rhizoctonia seedling blight: This disease is caused by the fungus Rhizoctonia solani and can cause seed rot, seedling damping-off, and root decay in corn seedlings. It is more common in warm, moist soils.

Common smut galls can form on most corn plant tissues.
(Photo by D. Mueller)

Common smut: This is a fungal disease that can infect young corn plants, causing swollen, distorted galls on the plant. It is spread by spores and can be more common in fields with high nitrogen levels.

Soybean Diseases

Seedling damping off from Pythium seedling blight and root rot. (Photo by M. Chilvers)

Pythium seedling blight: This disease can also affect soybean seedlings, causing seed rot, seedling damping-off, and root decay. Soil will stick to infected seeds, which appear rotted and may have water-soaked lesions on they hypocotyl or cotyledons that develop into a brown soft rot. It will be easy to pull diseased plants from the soil due to rotted roots. Saturated soil, with lower temperatures (50 to 60°F) in the north and warmer temperatures (85 to 95°F) in the south, are the most common conditions for disease prevalence. Avoid planting in cold, wet soils and utilize a premium seed treatment that targets Pythium to protect soybean yield potential.

Early season symptoms of Phytophthora sojae infection include damping off. (Photo courtesy of Crop Protection Network)

Phytophthora root and stem rot: This disease is caused by the soil-borne fungus Phytophthora sojae and can cause wilting, stunting, and root and stem rot in soybean plants. It thrives in warm, wet soils. Phytophthora root rot is more severe in no-till fields, poorly drained soils, or low-lying areas that are prone to flooding.

Damping off caused by Rhizoctonia seedling blight and root rot. (Photo by M. Chilvers)

Rhizoctonia seedling blight: This disease can also affect soybean seedlings, causing seed rot, seedling damping-off, and root decay. Caused by the fungus Rhizoctonia solani, infected seedlings will show reddish-brown lesions on the hypocotyls at the soil line. The fungus survives on plant residue or in soils as sclerotia. Infection may occur soon after seed is planted. Cool, wet springs followed by hot, dry conditions are conducive to disease.

Crushed brown cysts with eggs are signs of soybean cyst nematode. (Photo by Kaitlyn Bissonnette)

Soybean cyst nematode: This is a microscopic worm that can infect soybean roots, causing stunting and reduced yields. It is more common in fields with a history of soybean cyst nematode infestations. SCN is considered the most yield limiting disease of soybean in the U.S. and Canada with estimated yield losses exceeding 125 million bushels annually.

Talk to your AgVenture Yield Specialist about the best products to plant in each field. Make sure your seed investment is protected with a premium Security Seed Protection System™ treatment package.