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This article discusses the factors affecting stand establishment in corn, including planting conditions, tillage, planter functionality, weather, and climate. It also explores the risks of planting into colder soils, emergence risks with cold/frost after planting, and damage from diseases and insects. The importance of seed quality and the sensitivity of corn emergence to stress are highlighted. Additionally, the article provides insights into the effects of fluctuating soil temperatures and cold temperature damage on corn seedlings.
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Spring Agronomy Reminders Early Season Stress in Corn
When Will Planting Begin?… Expected based on recent trend
Quote “I never went to the Indy 500 as a kid because we were always planting corn” • Tom Sinclair, USDA Agronomist (3rd to 4th week of May annually)
Some Common Trends • Faster Planting from Start to Finish • Significant increase in planter capacity • Wide Spring Temperature Swings • Risk of Planting into Colder Soils (<50ºF or less) • Emergence Risks with Cold/Frost after Planting • As much as 3 to 4 weeks to emerge in some years • Damage from Diseases and Insects • Significant help from seed treatments but not 100%
Factors affecting stand establishment • Planting Conditions • Tillage Conditions • Planter Functionality • Weather / Climate • Stress Emergence • Seed Quality
Early Season Stress Good Planting Conditions Snow After Planting Poor Stand Seedling Damage
Yucatan, Mexico, April 29 Soil temp 77 °F ON, Canada, April 29 Soil temp 42 °F Tropics vs. North America
Soil Temperature and Root Growth Growth Rate (In / day) Soil Temperature (ºF) Optimum soil temperature for emergence is ~85 ºF
The RisksFluctuating soil temperatures cause stress on seedlings Iowa • Data from Iowa State University IEM
How close to a “stress event” can I plant corn? Replant! Average early root and shoot growth rates for three hybrids under four soil temperatures ranging from 59 to 95F. Number of hours with good conditions before imposed stress emergence (melting ice)
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
Imbibitional Chilling Injury Exudate triggers attack by soil fungi & insects Soil Cell Membrane
Cold Injury Symptoms Classical cold injury Cold, temperature swings, herbicide injury
Cold Damage Key Points • Corn 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 effects • Uniformity key for germination and even emergence • The 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)