Stalk Strength and the Importance of Scheduling Harvest Order

BY Dairyland Seed Agronomy Team

Recent strong wind events are exposing some weakened stalks. It’s not uncommon to see stalk strength start to diminish late season, but this year’s growing conditions likely sped up the process. The frequent rain events this spring forced field work and planting in less-than-ideal conditions. This resulted in several corn fields experiencing compaction, sidewall compaction, or shallow roots. When roots can’t take up enough nutrients coupled with high temperatures that speed up plant development, it’s very common to see stalk cannibalization. The corn plant will steal carbohydrates from the stalk and use that to fill kernels in the ear, leaving the stalk tissue depleted.

Stalks that have been cannibalized decline and lose their ability to fight off pathogens. Soil borne pathogens can then invade and colonize the plant much easier, resulting in crown and/or stalk rots. Plants infected with crown or stalk rots are at risk for lodging. Usually, we see more wind events in October and November which can also impact standability.

The disease that I believe is very prevalent this year is fusarium. The photo above shows a corn plant with fusarium that has both crown and stalk rot.

Other common diseases we could see are:

Anthracnose which is mainly thought of as top dieback disease but the more advanced stages of the disease show black lesions on the stalk
Physoderma Brown Spot which in most instances is a leaf disease but can cause stalks rots that is associated with a brown or black ring around one or several of the lower nodes on the stalk
Diplodia Stalk Rot can be found in both the stalk and the ear or kernels with stalks and kernels a rough texture it tends to cause affected tissue to have black fungal formations on it
Gibberella Stalk Rot which is very similar in appearance to Fusairum and is tough to discern which one it is due to both cause pink/red or salmon colors inside the stalk.

The procedure that I follow to check fields is to review which fields were planted in “less than ideal conditions” as well shorter day hybrids and scout them first. I will then walk across a portion of the field and perform Pinch, Push, Shove and Slash tests along the way.

Pinch the stalks 4-8 inches off the soil level. If it collapses, you have a crown or stalk rot, or both.
Push the stalks so the top of the plant touches the row across from it. If it buckles under that pressure, odds are you have a stalk rot.
Shove a few stalks down the row and see how much pressure it takes to break them. The less pressure it takes to break them increases the probability of standability issues.
Slash or cut the stalk 10-12 inches above the soil line with a sharp knife down to or through the roots. (Remember to be safe and cut away from yourself.) I generally will dig the plant first. The crown and stalk should be a white or creamy color. The photo below shows a healthy stalk and root on the left, whereas the stalk and root on the right is not healthy. If it is not, that plant has a crown or stalk rot.

The more plants that fail these tests increases the odds that you will need to harvest that field early or move it up in the harvest schedule. Remember that these affected plants will be more susceptible to wind damage the longer the harvest window gets.

Having and following a harvest order decreases the likelihood of harvesting down corn, and increases the likelihood of capturing more yield but also having a safer and less stressful harvest season.