Stalk Quality

Overview

Stalk quality represents the ability of the stalk to remain firm, rigid and upright through harvest.

A number of factors influence stalk quality. First and foremost is yield. During kernel development energy is drawn from the top third of the plant. Less than ideal sunlight or temperature will cause the plant to rob energy from the roots and stalks. Higher yielding hybrids tend to put more stress on the stalk.

Root structure also plays a role. In most cases, stalk-rotting organisms enter the plant through the roots. A larger more fibrous root system is better equipped to fend off the attack of the fungal and bacterial stalk-rotting invaders.

Finally, the plant's genetic background contributes to stalk quality. Some genetic lines simply produce a better stalk.

How we test

iCORN's rating for stalk quality is a measure of the stalk strength at normal harvest moisture (15% to 22%).

We conduct stalk observations and tests beginning at black layer (28% to 32% moisture). Because the rind supports the plant, we conduct a compression test to determine the rind strength (resistance to being crushed). We perform the stalk test by pinching the rind approximately 10 inches above soil level-the point where breakage is most likely to occur. Generally speaking, green plants have more strength so we observe and record visual rating of stay green.

We repeat these tests and observations periodically beginning at black layer and continuing to approximately 15% moisture.

iCORN performs these tests in each region where we recommend the hybrid.

Our rating scale

Our rating scale ranges from 0 to 9, with 9 being the best score. Since lodging is the unforgivable sin, iCORN doesn't offer hybrids rating 5 or less. Here's the definition of our ratings.

Pliable but not mush, little to no green color. Stalks with this rating are acceptable in the west but caution in the East. The only way a 6 will make it into the iCORN lineup is if it is an exceptionally high yielder. Hybrids rated a 6 generally need to be harvested at 18%-20% moisture or higher.
Generally firm but under moderate stress can lead to some (5%-7%) stalk breakage at harvest. Sevens are acceptable west of Route 31 in Indiana. East of Route 31, stalks with a rating of 7 would not be recommended for late harvest.
Green and firm stalk, even into late drydown. Stalks with an 8 have few restrictions. High disease, river bottoms and corn-after-corn are all acceptable environments for an 8.
Green and hard, a near perfect stalk. Under iCORN's rating system, few hybrids ever score a 9.