With a new season upon us, it will soon be time to start assessing corn stands. In a perfect world, we would have uniform, perfect stands in every field, every year.

However, the reality is there are times when we are faced with adverse conditions that could result in stand establishment issues when we look at our corn stands from mid-April to mid-June. 

Less-than-ideal environmental conditions or pests could impact seedling survival or the quick emergence that we are hopeful for. There are also a handful of seedling diseases caused by soil-borne organisms like Pythium, Fusarium, and Rhizoctonia that will cause delayed emergence or seed rotting/decay.

Planting conditions and conditions shortly after planting are important to keep in mind as we begin to consider what is a favorable environment for these diseases to take place. With most seedling diseases, cool and wet soil conditions pose the highest risk.

A few signs to look for when determining if a stand is affected would be skips between plants that did not emerge, above-ground stunting or damping off, or a field with a poor/uneven stand.

Seedling with post-emergence damping off (left) next to a healthy seedling. Photo Credit: Tamra Jackson- Ziems

To determine if it was a disease that affected emergence, we will need to break out our shovels and investigate the seedlings or plants below ground to see if disease or insects are present. Some insect pests, like seed corn maggots and wireworms, can harm the embryo, resulting in failed emergence. The most common pathogens affecting corn seedlings include Pythium, Fusarium, and Rhizoctonia.

Rotted or decayed mesocotyl, pre- or post-emergence death, yellow to brown root system, water-soaked tissue, above-ground stunting

High moisture, areas of field that hold
more water such as poorly drained or compacted areas

Pythium seedling blight symptoms. Photo Credit: G. Munkvold, G. Ruhl, and A. Robertson

 Tan to reddish brown lesions that cause the mesocotyl to decay. Early infection may also lead to stunting, wilting, and crown rot later

Stressed plants from cooler temperatures, compacted or wet soils, herbicide injury or stress

Rotted seedling mesocotyl. Photo Credit: G. Munkvold, G. Ruhl, and A. Robertson

In young seedlings, reddish-brown lesions form on the mesocotyl and roots. Infection in older plants can cause brace root rot or crown rot and lead to lodging

Likes warmer, drier conditions for its development, contrary to most of the other seedling diseases that thrive in wetter, cooler conditions

Reddish-brown root lesions typical of Rhizoctonia root rot. Photo Credit: Tamra Jackson-Ziems

Plant into soil temperatures 50ºF or warmer for a less favorable
environment for Pythium and Fusarium.

If possible, improve soil drainage to allow for a healthier root system to develop.

Reduce stressors on young plants, such as compaction, planting depth, and crusting.

Protect your seed with a comprehensive seed treatment that contains a fungicide to help protect against these seedling diseases and assist with stand establishment. Beck's Escalate® seed treatment contains a fungicide package that includes multiple modes of action against Pythium, Fusarium, and Rhizoctonia.