How do you accurately growth-stage corn once the coleoptile has fallen off? Grab your favorite knife and slice a few plants…

Accurately staging corn plants following emergence is as simple as counting the number of visible leaf collars present on the growing stalk. However, at some point in the early vegetative phase of growth, the coleoptile will “burn off” and is no longer visible. This usually occurs somewhere around V4. Since this coleoptile is leaf # 1 or “V1”, you no longer have a starting point. So what now??

Carefully remove an entire plant from the ground, making sure you get the entire base of the plant intact, as shown above. Slice the plant in half along the main stalk. A razor blade works best, but any pocket knife does just fine.

Locate the pithy triangle at the base of the plant. This is the area where nodes 1 – 4 are located, and leaves 1 – 4 all had their origin in this area.

Next, locate the first internodal space immediately above this area, and follow it up the stalk until you locate the next node. This is where leaf 5 attaches to the plant. Locate the leaf sheath that connects here, and then the leaf collar that is attached to that leaf. This is leaf 5.

Now, you can go back to counting collars up to the last visible leaf collar present.

While plant height is an important consideration for certain herbicide labels, many also specify a growth stage as well with a “whichever comes first” statement. This is just another tool in the box for knowing exactly where your corn is during mid-late vegetative growth.

Jake