Deep in the DNA of a corn seed lies a genetic predisposition to thrive in tropical temperatures. The optimum temperature for a corn seedling to emerge is 80–90 degrees F. However, soil temperatures at planting are more likely to be at 50­–55 degrees F — the temperature at which emergence is inhibited.
To help growers select the right product for their planting conditions, researchers at DuPont Pioneer identify and measure the genetic differences among Pioneer corn products and their ability to emerge in high-stress environments. The result is a Pioneer agronomic rating called Stress Emergence
Pioneer researchers test hybrids in a wide range of stressful environments in the lab and field and measure stand establishment. Hybrids are rated relative to other Pioneer hybrids. No uniform industry rating currently exists.
Pioneer Stress Emergence ratings are assigned on a 1–9 scale. Ratings of 6–9 indicate above-average potential to establish normal stands under harsh conditions; a rating of 5 indicates average potential to establish normal stands under stress conditions; and ratings of 1–4 indicate below-average potential to establish normal stands in cool soils.
Successful stand establishment begins by selecting hybrids with strong Stress Emergence scores. Growers can also take five additional steps to ensure strong emergence:

  • Insist on fungicide, insecticide and biological seed treatments pre-applied on the seed. 
  • Consider additional Premium Seed Treatments for specific insect pests.
  • Protect seeds by planting slightly deeper than normal (at least 2 inches).
  • Use planter-mounted row cleaners in heavy residue.
  • Plant at soil temperatures above 50 degrees F.