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Evaluating Stalk Quality to Maximize Yields
What affects stalk quality?
Plant stress — drought, disease, hail, pest feeding — impedes the plant’s ability to photosynthesize and produce carbohydrates.
With photosynthesis limited, corn prioritizes ear development and kernel fill, sending energy to the ear and leaving fewer carbohydrates available to other areas of the plant.
As carbohydrates get directed to corn ears, less is available to stalk tissue, which weakens it, increasing stalk rot and lodging risk.
As harvest nears and excitement builds for farmers and seed companies alike, nothing can cause that optimism to fade faster than down corn. Farmers know that if corn doesn’t have good standability throughout the season, they’ll lose yields at harvest. And while many factors — heat, rainfall, drought, hail — are out of their control, assessing corn’s stalk quality can help them plan their harvest calendar to maximize each field’s yield potential.
Why stalk health is important
Many factors affect corn’s ability to maintain stalk health. During corn ear development, the plant produces a significant amount of carbohydrates, but any stress that decreases the energy produced forces the plant to preserve grain fill at the expense of stalk quality. (see graphic) Carbohydrates are redirected to the ear, leaving the roots and stalk weak and less able to resist further disease and lodging. Stress from insect feeding, disease pressure, drought, frost or other weather issues can all affect stalk quality. For example, hail damage decreases the leaf area available for photosynthesis and carbohydrate production, causing poor stalk development. Too little sunlight can limit photosynthesis as well. Even summer’s high temperatures and dry conditions are stressors, accelerating crop maturity and forcing plants to direct most of their energy to grain fill.
Poor stalk health puts corn at an increased risk of lodging, which can make harvest more difficult and significantly reduce yield — from 5% to as high as 43% — depending on when lodging occurs, according to a three-year Ohio State University study.1 Different stressors throughout the growing season can affect stalk quality:
- Seeding rate is important, since competition among closely planted plants can reduce stalk thickness and increase lodging risk.
- Soil fertility — such as having high nitrogen or low potassium — can negatively affect stalk quality.
- Multiple diseases that weaken corn plants could be present at the same time in the same field, including Anthracnose, Diplodia, Fusarium and Pythium. Without the use of foliar fungicides, farmers could see significant losses.
- Severe weather such as high winds or heavy rain during dry-down could become a significant lodging risk for weak stalks.
How to check for stand issues
Timely decisionmaking is essential to help farmers preserve yield potential at harvest. Two or three weeks before harvest, farmers should begin to carefully scout fields for stalk quality indicators and identify any standability concerns. With this scouting information, farmers can create a harvest plan that prioritizes at-risk fields. Any (or all) of the steps below can help farmers evaluate fields, identify stalk rot and other stand issues, then determine which fields to harvest early.
Split stalks open to gauge stalk health – Do a visual check of stem interiors, looking for cannibalization or a styrofoam-like appearance.
Conduct a pinch test – At one of the lowest two internodes, pinch the stalk between your thumb and finger. If that pressure is enough to crush the stalk, it fails the test.
Do a push test – Push a stalk at ear level. If the stalk bends or breaks between the ear and lower nodes, stalk health may be compromised, putting plants at greater risk of lodging.
No matter which method — split, pinch or push — farmers should check at least 100 plants per field. Experts at the Iowa State University Extension recommend evaluating 20 plants from five different areas of a field, being especially vigilant about checking areas that have corn rootworm pressure or are at risk of damaging winds. If 10% or more of the sampled plants fail the test, they could be at greater risk for lodging issues. Farmers should prioritize these fields for harvest. They may also want to harvest at a reduced ground speed to minimize grain loss.
While many farmers determine their corn harvest schedule based on dry-down, potential yield loss from poor stalk health should receive equal consideration when deciding which fields to harvest first. Farmers may want to consider starting harvest at 20%-25% moisture to reduce lodging risk.2
When farmers start choosing hybrids for their fields next season, suggest they look for strong ratings for resistance to major leaf diseases and stalk rots along with good standability scores.
While poor stalk quality can dramatically affect yield at harvest, scouting, testing and monitoring can help farmers identify problem fields, allowing them to plan their harvest schedule to maximize returns.
1 Alex Lindsey and Peter Thomison, “Corn Yield Response to Damage from Strong Storms,” Ohioline, Ohio State University Extension, February 23, 2022, https://ohioline.osu.edu/factsheet/ac-1054.
2 Rhonda Brooks, “Focus on Stalk Quality to Maximize Harvest Results,” AgWeb, September 8, 2025, https://www.agweb.com/news/crops/harvest/focus-corn-stalk-quality-maximize-harvest-results.