March 28, 2023
- There are many issues that may contribute to reduced corn populations including planting, insects, diseases, and/or environmental conditions. Replanting is not an easy decision, and numerous factors determine a crop’s yield potential.
- The main objective of the trial was to determine how much loss in yield potential can be expected with reduced plant stands and when a replant is justified.
RESEARCH SITE DETAILS
|Planting Date||05/24/22, 06/07/22|
- This study was planted at the Bayer Market Development Research Farm located in Canandaigua, NY.
- The trial was a complete randomized design with four replications.
- Individual plots where 10 feet wide by 250 feet long.
- Plots were planted in 30-inch rows with a four-row planter.
- 210 lb/acre nitrogen was split applied with 50 lb/acre applied as a 2x2 starter and 160 lb/acre applied sidedress at V3.
- 25 lb/acre phosphate and 160 lb/acre potassium was preplant applied.
- All other agronomic inputs followed local standards.
- Two 99 -relative maturity (RM) corn products were used for this trial.
- One semi-flex ear corn product and one semi-determinate ear corn product.
- Six plant populations were tested 30,000, 27,000, 24,000, 21,000, 18,000, and 15,000 seeds per acre. This represented 100%, 90%, 80%, 70%, 60%, and 50% of the desired population respectively.
- Randomization of plant placement was done by mixing corn product with glyphosate-resistant trait with conventional non-traited corn at ratios of 100:0, 90:10, 80:20, 70:30, 60:40 and 50:50, respectively (Figure 1). Plots were sprayed with glyphosate at the V3 growth stage to kill the conventional corn to mimic stand reduction.
- A second planting of both corn products at 30,000 seeds per acre was planted two weeks after the initial trial to check yield reduction due to late planting.
- Average yield (bu/acre) determined by harvesting with a Kincaid 8XP small plot combine using the two center rows of the plot to collect weight, moisture, and test weight data.
- All yield data was corrected to 15.5% moisture.
Figure 1. Seed lots used to establish final plant populations. Photo taken on 5/16/2022 at the Bayer Market Development Research Farm in Canandaigua, NY.
Figure 2. Overhead drone photo that shows the different final plant populations established with the different seed lots. Photo taken on 7/15/2022 at the Bayer Market Development Research Farm in Canandaigua, NY.
UNDERSTANDING THE RESULTS
Table 1. Loss in yield potential for two corn products due to reduction in stand or replant (Canandaigua, NY, 2022).
- The average yield loss for both corn products was not proportional to the loss in plant stand (Table 1).
- The 99RM semi-flex ear corn product planted two weeks later yielded 194 bu/acre with a 54.3 lb/bu test weight.
- The 99RM semi determinate ear corn product planted two weeks later yielded 204 bu/acre with a 53.1 lb/bu test weight.
- Data from this 2022 study indicates that under these growing conditions and using these corn products it took a plant stand loss of over 30% to justify replanting the semi-flex corn product two weeks later. In this study, the replanted crop did not out yield the original planting with a 70% stand loss (Table 1).
- Similarly, it took a stand loss of over 20% of the semi-determinate corn product for replanting to be warranted.
- The additional crop revenue from a replanted corn crop must consider the added replant costs.
- Understanding how uneven emergence impacts yields is a factor that was not considered in this trial.
- This study demonstrates that even with significant population losses, yield potential may be as good or better than yields obtained from a replant.
- In addition to comparing yield potentials, the cost of replanting should also be considered. Additional replant costs include destroying the original crop, replant seed cost, labor, equipment, and potential additional herbicides.
- Always ask your agronomist or seed dealer for the recommended planting population for your area and the corn products used. A 30,000 seeds/acre population was used for this trial but does not guarantee optimal yield return for all corn products.