Today managing your corn crop requires knowledge of the different growth stages of the corn plant. Growth stage identification is critical for scouting and proper timing of fertilizer and pesticide applications. Each week throughout the growing season I will discuss the various corn growth stages and management issue at each stage. 
V3 – V4 – 350 – 400 Growing Degree Days (GDD’s)
Photo source: Iowa State University
The V3 stage is reached approximately 10 – 20 days after emergence. At this stage the photosynthesis process begins and the plant no longer relies on the seed as its food source.
The nodal root system takes over for the seminal root system. The nodal roots continue grow and begins to develop root hairs.
The corn plant is erect due to the combined strength of the leaf sheaths layered on top of each other. Leaves are still developing and the growing point remains underground.
Management/Scouting: Scout for root rots, seedling blight, cutworms, slugs, billbugs, Herbicide injury, flooding, weed escapes and excess weed competition.