Crop Management Demo-Uneven Plant Emergence

Why does uneven emergence sometimes happen within the same field? Common causes include planting into wet soils and planting in fields with a higher level of residue. Pioneer evaluated how uneven emergence affects corn growth and development in its uneven emergence goof demonstration.

In this goof demo, corn was planted on May 7, 2009. To emulate three distinct emergence patterns, 13 days later when plants had emerged and were at the V1 stage, every third plant in the row was either clipped at the surface or removed and then replanted by hand.

Seven days later, the clipped plant was slightly behind in development compared to the check plant. The hand-planted seed was just emerging.

Three weeks later and nearly 500 Growing Degree Units (GDUs), the plant that was clipped on May 20 was approximately one collar behind in growth compared to the check plant. The hand-planted seed was two collars behind in growth.

Nearly two months after the initial planting, the differences in root development begin to tell the story of how important uniform emergence is throughout a field.

The check plant had good root development while the root growth on the clipped plant was similar but just slightly behind in development. However, the hand-seeded plant was developing much slower, likely because it was being shaded out. According to Jeff Mathesius, Pioneer agronomy research manager, the hand-seeded plant was actually acting more as a weed in the field than contributing as a corn plant.

Three months later, the check plant had a thick stalk and good root system. The clipped plant had good stalk development but limited brace roots. The stalk of the hand-seeded plant was spindly and weak.

Ear development helps show the significance of uneven emergence. The clipped plant had normal ear development but the silk indicated it was slightly behind development compared to the check plant. Why is this so important? According to Mathesius, any type of late-season application where timing is critical, as is the case with foliar fungicides, can have a significant and potentially negative effect on plant development and yield.

"It's critical that foliar fungicides be applied after plants are flowering," says Mathesius. "Even if there is only a slight difference in plant and ear development throughout a field, there is the potential for significant damage if a fungicide and non-ionic surfactant are applied when some of the corn in the field is at the wrong growth stage. It's amazing how important what happens to corn plants early in the season and how it impacts growth and yield as the season progresses." He adds the weather delays in 2009 caused some growers to plant in less than ideal soil conditions, potentially increasing the risk of uneven emergence.

Why does uneven emergence sometimes happen within the same field? Common causes include planting into wet soils and planting in fields with a higher level of residue. Pioneer evaluated how uneven emergence affects corn growth and development in its uneven emergence goof demonstration.