1. Spring Agronomy Reminders Early Season Stress in Corn

2. Expected based on recent trend When Will Planting Begin?…

3. Quote “I never went to the Indy 500 as a kid because we were always planting corn” –Tom Sinclair, USDA Agronomist ( 3 rd to 4 th week of May annually )

4. Some Common Trends Faster Planting from Start to FinishFaster Planting from Start to Finish Significant increase in planter capacity Wide Spring Temperature SwingsWide Spring Temperature Swings Risk of Planting into Colder Soils (<50ºF or less) Emergence Risks with Cold/Frost after PlantingEmergence Risks with Cold/Frost after Planting As much as 3 to 4 weeks to emerge in some years Damage from Diseases and InsectsDamage from Diseases and Insects Significant help from seed treatments but not 100%

5. Factors affecting stand establishment Planting ConditionsPlanting Conditions Tillage ConditionsTillage Conditions Planter FunctionalityPlanter Functionality Weather / ClimateWeather / Climate Stress EmergenceStress Emergence Seed QualitySeed Quality

6. Snow After Planting Good Planting Conditions Seedling Damage Poor Stand Early Season Stress

7. Why is Corn Emergence Sensitive to Stress?

8. Tropics vs. North America ON, Canada, April 29 Soil temp 42 °F Yucatan, Mexico, April 29 Soil temp 77 °F

9. Soil Temperature Effect on Growth & Development

10. Soil Temperature and Root Growth Soil Temperature (ºF) Growth Rate (In / day) Optimum soil temperature for emergence is ~85 ºF

11. The Risks Fluctuating soil temperatures cause stress on seedlings Data from Iowa State University IEM Iowa

12. How close to a “stress event” can I plant corn? Number of hours with good conditions before imposed stress emergence (melting ice) Replant! Average early root and shoot growth rates for three hybrids under four soil temperatures ranging from 59 to 95F.

13. Cold Temperature Damage

14. Imbibitional Chilling Injury Cell membranes are brittle in the cold Force of hydration causes membrane rupture Leaked cell contents invite pathogens Water temperature during initial contact is critical Most damage occurs during imbibition at < 50°F

15. Exudate triggers attack by soil fungi & insects Cell Soil Membrane Imbibitional Chilling Injury

16. Cold Injury Symptoms Classical cold injury Cold, temperature swings, herbicide injury

17. Cold Damage Key Points Corn is almost always under severe cold stressCorn is almost always under severe cold stress Ideal temperature for emergence is in the high 80’s Small variations in seedbed environment or timing of stress can have dramatic effectsSmall variations in seedbed environment or timing of stress can have dramatic effects Uniformity key for germination and even emergence The first hours (24-48 hours) are the most criticalThe first hours (24-48 hours) are the most critical Cold damage risk reduced significantly after this time Plant into a warming trend (>50F and rising preferably)