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Stress Emergence Ratings Differentiate Corn HybridsStress Emergence Ratings Differentiate Corn Hybrids

Early planting and crop residue set stage for planting in cool soils; here are tips to help improve corn emergence.

March 19, 2014

3 Min Read

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 to 90 degrees F. However, in Iowa soil temperatures at planting are more likely to be at 50­ to 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 hybrids and their ability to emerge in high-stress environments. The result is a rating called Stress Emergence. Pioneer agronomists 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 to 9 scale. Ratings of 6 to 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 to 4 indicate below-average potential to establish normal stands in cool soils.

Iowa is getting closer to planting season; soils will likely be cold
Successful stand establishment begins by selecting hybrids with strong Stress Emergence scores, the company's agronomists advise. They say growers can also take five additional steps to ensure strong emergence:

1) Insist on fungicide, insecticide and biological seed treatments pre-applied on the seed. 

2) Consider additional Premium Seed Treatments for specific insect pests.

3) Protect seeds by planting slightly deeper than normal (at least 2 inches).

4) Use planter-mounted row cleaners in heavy residue.

5) Plant at soil temperatures above 50 degrees F.

For more information, contact your Pioneer sales professional, or visit the Pioneer website.

Tips to help mitigate early-season stress effects on emergence
Delayed emergence due to cold, wet conditions lengthens the duration during which seed and seedlings are most vulnerable to early-season insects and diseases. Seed treatments can help protect stands from both disease and insect pests. The PPST 250 seed treatment, standard on all Pioneer brand corn hybrids in the U.S., includes fungicide (multiple modes of action), insecticide and biological components. In areas with high nematode or insect pressure (such as cutworm or wireworm), growers can choose the added protection of Poncho 1250 + VOTiVO seed treatment. For more information on seed treatments contact your local Pioneer sales rep or visit the soybean seed treatment and corn seed treatment sections on www.pioneer.com/.

Every decision that you make influences the size and scope for corn yields. From the corn hybrid you select to the seeding rate and row width you choose. Download our FREE report over Maximizing Your Corn Yield.

Planting date is one of the most important factors
Planting date is one of the most important factors in stand establishment. The likelihood of reduced corn stands is greatest when planting into cold, wet soils or directly before cold, wet weather is expected. To help mitigate risk, consider the following tips:

1) If a cold spell is expected around planting time, it is advisable to stop planting 1 or 2 days in advance. Allow seed to begin hydration in warmer soils in order to minimize damage due to cold imbibition.

2) In sandy fields, be aware that low night time temperatures can dip soil temperatures below advisable planting levels. Large temperature swings in lighter soils can also hurt emergence.

3) If planting in fields with high amounts of crop residue, consider using strip-tillage or use a row cleaner to allow soils to warm up faster.

4) Selecting hybrids with higher stress emergence scores and the right seed treatment can help reduce the risks associated with planting in cold-stress conditions.

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