A website from UGA Cooperative Extension

With our cool temperatures, growth has slowed us down a lot with our produce and corn. But this week corn is growing with warm days and sunny skies giving us some Heat Units. This corn is right at the V7 growth stage. Much of the yield is determined at V6. The number of rows of kernels around the cob is established around this time as well. The growing point is now above the soil surface, so any frost would hurt it. This is why we don’t¬†plant too early – when it’s warm in February.

Of course our weed control is important, and according to UGA Corn Weed Scientist Dr. Eric Prostko, it is worth 36% of our yield. But remember, so much happens early with corn, and plants stressed at this time can hurt yield. At this time, we need to cut off our over-the-top herbicide sprays. Not only do we lose coverage, but once we get past V6, we can LOSE yield in corn. So, if we use herbicide now, we need to be post-directed.

Growth Stage

How do we check this stage? The easiest way is to locate the collar on the back of the leaf. Your vegetative growth stage (ex. V7) is the fully expanded leaf with a collar on the back side. As you can see in the picture below, there are 6 leaves from the bottom to where the collar is showing, but there are 2 other leaves coming out of the whorl. Those 2 leaves do not count in the growth stage.

At this stage, the 1st leaf is usually not visible. Counting from the second leaf, the collar is showing on leaf 7. Leaves 8 and 9 are coming out of the whorl.
Posted in: ,