Wet spring conditions in 2019 compromised early season root growth in corn plants, which, in turn, affected nitrogen availability and uptake. As we approach harvest, symptoms of nitrogen deficiency in the form of leaves firing from the bottom are prevalent in many fields.
While some of the firing may be a symptom of moisture deficiency stress, it also is likely due to nitrogen deprivation. This is a natural reaction as the plant tries to redistribute nitrogen in the lower parts of the plant upward to feed the ear and promote kernel development. While the plant cannibalizes available nitrogen within the stalk for grain development, it also compromises the integrity and fibers of the stalk that help keep the plant strong and sturdy leading into harvest.
Scout for stalk rot symptoms
This season, poor root development early in the season and nitrogen deprivation are likely the most common causes contributing to compromised stalk integrity, but other factors may play a role. Drought stress and foliar disease pressure — especially in later planted fields — are stresses that can lead to stalk problems when followed by a less favorable environment. Many additional factors, including cropping history and soil fertility, can heighten stalk integrity issues.
As harvest approaches, monitor fields to identify stalk quality problems. There are a few ways to do this:
- Push stalk tops away: As you walk through a field, randomly select a minimum of 100 plants that represent a large portion of the field and push the stalk tops away from you approximately 30 degrees. Plants that don’t snap should be a concern.
- Pinch the internodes: If you pinch the internodes of the lower stalk and the stalk crushes easily by hand, that could indicate stalk rot and mean your stalks are prone to lodging.
- Split open stalks: You can also split open stalks to look for discoloration, indicating loss of stalk fiber integrity that may appear as rotting or have a stringy appearance.
Prioritize fields based on stalk conditions
Scouting two to three weeks before your expected harvest date can help you develop a plan that includes prioritizing fields according to crop condition. If more than 10% of stalks in a field have symptoms of stalk rot, consider prioritizing that field to limit the possibility of stalk lodging. If conditions worsen, balance corn loss potential and grain moisture when deciding which fields to harvest first. Drying expenses may be a better option compared with loss of yield due to stalk rot and stalk lodging.
Many of the fields that may have standability issues are a result of conditions in 2019 that we hope to never experience again. As you begin to think about 2020, work with your local retail team and agronomist to consider fertility plans and identify hybrids with high stalk strength and good disease ratings.