The cool and wet spring has created a slow start to spring applications and planting this spring. Soil temperatures have had difficulty rising to near the 50-degree mark and overnight temperatures continue to dip into the mid-30s.

With less-than-ideal planting conditions, farmers that were able to plant corn should scout for emergence issues related to cold damage, such as seedling diseases and corn chilling.

As farmers know, yield potential lowers with each day planting is delayed. If a replant is needed, it’s best to know it sooner rather than later.

Seedling Diseases

Cool soils combined with wet conditions will slow the germination process of planted seeds. Seeds should take between seven and 14 days to germinate in ideal conditions.

The longer seeds sit in the ground, the higher the probability of having seedling diseases like Pythium and Fusarium. These diseases attack the seed and roots of slow-growing plants.

Unfortunately, with early seedling diseases, you generally need to wait until the plants have germinated before you can see their effects. For instance, you may notice areas of the field, especially low-lying areas or compacted areas, with stunted or yellowing corn plants. You may also notice bare patches where seeds rotted in the ground before germination.

Seed treatments can offer protection from many key seedling diseases. However, it’s still important to dig up seedlings, both healthy and nonhealthy plants, and examine them for these key symptoms:

  • Roots should be white. Dark-colored roots can indicate cold stress or a fungal infection.
  • Seedlings should be firm and not mushy. Mushy seeds are likely rotted.
  • Look at roots for insect feeding, rotted roots, brown lesions on the mesocotyl regions and other injuries.

Corn Chilling

“Cold chill inhibition” is the term used when germinating plants absorb water and soil temperature drops below 50 degrees during the first 24 to 36 hours after planting.

The cold water taken up by the seed causes the cells to weaken and burst. Those who’ve experienced a cold snap after planting should scout fields for signs of inhibitional chilling injury.

Start by digging up plants within two weeks of planting and look for irregular elongation or “corkscrewing” of the mesocotyl or “leafing out” underground with delayed or failed seedling emergence. Additionally, farmers will see an uneven stand as the crop emerges. Uneven stands could signal herbicide injury or compaction issues.

If inhibitional chilling injury occurs, replanting as soon as possible is the only way to avoid yield loss. Otherwise, a farmer may leave 15% to 20% of yield in the field.

The earlier a farmer replants, the more promising the yield. Farmers may still see plants emerge after having chilling injury, but as a consequence, these plants will yield less.

Wait For Ideal Conditions

It’s easy to feel the pressure to get the crops in the ground. But even with the delay of planting, it’s still important to wait for soil temperatures to rise to avoid these challenges. Corn can be planted up until May 15 and still hit 95% of yield potential.

For more information, contact your local agronomist or visit Mycogen.com/Agronomy.

® Trademarks of Dow AgroSciences, DuPont or Pioneer, and their affiliated companies or their respective owners. © 2019 Mycogen Seeds.

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