V5+ Corn Plant Development

When a corn plant reaches the V5 stage, it has reached a very important stage in plant development. The importance of the V5 growth stage in corn:

The growing point is above ground and is 1-1½ inches above the soil surface.
The plant is determining what the number of rows around the cob will be.
The nodal root system has become the major root system in the plant.
Tillers or suckers are starting to form at the base of the plant.
The plant is starting its above ground growth spurt, and, with good growing conditions, the corn plant may double its height in a 10 to 14 day timeframe.

To use a parental analogy, your corn plant has entered its teenage years.

At the V5-V6 stage, the growing point is about 1 to 1½ inches above the soil surface. Plants that break off at or near the soil surface due to hail, sandblasting, mechanical damage (cultivator blight) or other means, will die.

While the growing point is coming out the ground, the number of rows around the cob is being determined. The row count or number of rows around the cob will always be an even number, with 14-18 rows around the cob being very common. The cob will drop rows at this stage if the plant is lacking moisture, nutrients due to a deficiency or poor root development, disease, insect damage, or lack of weed control.

The nodal root system is now the major root system of the plant, with roots being 8-12” across and 10-12” deep. If your corn plants were a lighter shade of green (this color has been referred to as the “Ghostbusters” yellow green slime color) prior to V5-V6, with proper available nutrients they should start to green up once the root system finds the nutrients in the soil it is growing into. If top dressing or side dressing Nitrogen or other nutrients is part of your nutrient management plan, now is a critical time to get it done. Root growth from now until Tassel emergence (R1) will be dramatic, as will the above ground growth, with plants potentially doubling in height in the next 10-14 days.

It seems as though color differences in specific hybrids or genetic families becomes more apparent at or slightly before that V5 growth stage. This is more apparent when you are in a plot situation and have many hybrids and genetic families to look at.

Another important consideration that comes into play at the V5-V6 growth stage is many Crop Protection Product (CPP) labels become more restrictive, either by growth stage or height restriction. (Due to the amount of replanted corn that has taken place in portions of the Dairyland Seed footprint, we may have corn that is approaching V5 and we may also have corn that is just emerging in the same field. This makes choosing the right time and right Crop Protection Product to utilize more challenging to say the least.) As a rule, I tend to follow the growth stage restriction when limiting CPP applications, this is due to the fact that I can also correlate growth stages by the amount of Growing Degree Unites (GDUs) that we have received since our planting date.

Another reason to choose growth stages over height in making decisions is that different hybrids and or genetic bases grow or put on height at different rates and can reach the same growth stage with different heights. Or, as in the case of the photo above, due to field growing conditions these two corn plants planted on the same day, in the same field with the same hybrid, are at the same V4 growth stage, but are vastly different heights.

If you have questions about how to stage a corn plant or the implications of the timing of spraying a certain herbicide, contact your local Dairyland Seed Agronomist.