- Always start your replant decision with an assessment of plant health, uniformity, remaining stand and yield potential.
- The yield advantage associated with replanting can be negated by replant costs exceeding the value of additional grain.
- The Golden Harvest® replant calculator simplifies the process for understanding replant yield advantage.
Many factors can cause unexpected stand loss or unevenness, and deciding to replant for desired plant population can be difficult. Before making a replant decision that incurs additional costs, it is important to evaluate plant health, remaining stand, uniformity and yield potential in comparison to what might be achieved by replanting.
Evaluating seed and seedling health
When corn is not germinating or emerging as it should, then it is time to dig. If the coleoptile (shoot), radicle (root) and seed tissue appear firm and healthy, then the seedling has a good chance for germination and emergence. However, if it appears water-soaked and mushy, then that indicates seedling decay. It is important to check the condition of the stand every few days to evaluate growth. If an emerged stand is uneven or damaged, then the potential for recovery and growth requires immediate evaluation of the growing point.
Dig up a few plants, and split them down the center. Look for a triangular-shaped structure at the point of nodal root growth, about ¾-1 inch below the soil surface. A healthy growing point will have a light-colored appearance with a firm texture. A damaged growing point will have a distinct yellow to brown, water-soaked appearance with a mushy texture.
Evaluating stands: Plant population and distribution
After an evaluation of plant health, determine the plant population and distribution (uniformity) of the existing stands. Count the number of viable plants in 1/1,000th of an acre and multiply that by 1,000 to obtain a plant population per acre. Plants that are weak or questionable should not be counted. Evaluate if plants are evenly spaced in the rows or if there are skips or gaps.
Existing stand potential versus replanting
Once you have evaluated plant health, remaining stand and uniformity, then it is time to determine yield potential of the current stand versus replanting. The following tables can be used to estimate stand potential. The yield values (expressed as a percent of maximum) are based on uniform distribution of plants within the rows, which is not typically the case.
Due to unique characteristics and adaptability, some hybrids can tolerate and compensate for lower stands better than others. However, if the existing stand is lower than the adapted population range of a hybrid, then replanting may be best.
To help transform your stand count information into a data-driven decision, Golden Harvest has developed a calculator to understand if existing stands will yield more or less than a delayed replant scenario.
Understanding the number of surviving plants is important for determining yield potential. However, yield potential can be further decreased without uniform plant emergence. Research has commonly found an additional 4%-6% yield loss when multiple plants (17%-75% of the stand) emerge 6-12 days later than the remainder of the plants. Uneven emergence can be quantified by comparing the number of leaf stages present between plants. In cases where there are differences of 2 or more leaf stages on at least half of the emerged plants, add an additional 10% yield potential toward the replant advantage of the field you’re evaluating.
Consider the economics
 |
Delayed field emergence with more than 2 leaf stages difference |
In the absence of a yield advantage for replanted corn, it is easy to decide to not replant. It is much more difficult to make replant decisions when small yield advantage exists. In these scenarios, it is important to consider replant seed, grain drying, herbicide, insecticide, tractor fuel, labor and equipment depreciation costs. Combined, these costs could easily offset a 5%-10% yield advantage for replanting.
Should you replant an earlier corn maturity?
Depending on when you can get back into the field to replant, you may need to consider moving to an earlier corn relative maturity. Careful consideration around anticipated fall frost dates and your ability to manage higher moisture corn must be understood when contemplating switching to an earlier corn hybrid.
Golden Harvest® replant calculator tip:
- Use your preferred browser to find the replant calculator at https://www.goldenharvestseeds.com/replant-calculator/
- Select the icon at bottom of the screen, and then select “Add Bookmark” to your favorites to have easy access when evaluating stands in your fields.
Contact your Golden Harvest Seed Advisor with questions or for additional agronomic insights.
Photos are either the property of Syngenta or used under agreement.
Syngenta hereby disclaims liability for third-party websites.