Posted on July, 25, 2024 at 06:37 am
Extending grain fill is important for improving corn yield. Overall, this period is critical due to its influence on final kernel size and dry weight. Grain fill duration and kernel weight accumulation in corn is typically a function of both late-season environmental conditions and plant health prior to maturity.
In 2022 and 2023, a research trial at Purdue University funded by the Indiana Corn Marketing Council studied how both fungicide use and corn disease control can influence grain fill duration and kernel weight. The research trial compared corn with and without a foliar fungicide applied at silk emergence, which is R1.
Ears were sampled weekly from R2, or milk stage, to maturity. The goal was to see how grain fill duration and kernel weight accumulation may or may not be impacted by sufficient disease control. In addition to the weekly ear samples, corn foliar disease severity ratings and final grain yield measurements were collected.
In both 2022 and 2023, these trials were impacted by foliar diseases — highlighted by tar spot, gray leaf spot and northern corn leaf blight. When corn ear leaves were rated at the R5, or dent, stage in 2022 and 2023, severity ratings reached 4% and 8%, respectively.
However, where a foliar fungicide was applied, ear leaf disease severity was reduced to 1% and 2% in 2022 and 2023, respectively. So, here was the first observation from the study: A foliar fungicide application has potential to reduce corn leaf disease severity when applied at R1.
However, here is the big question. What is the impact of improved disease control on length of grain fill, kernel weight and yield?
Length of grain fill boils down to days after silking until maximum kernel dry weight was achieved. In both 2022 and 2023, it was extended with a fungicide application at R1, and an observed reduction in leaf disease severity.
In 2022, applying a fungicide at R1 extended grain fill duration by four days and increased maximum kernel dry weight by 11%. This translated to an overall yield increase of 19 bushels per acre.
In 2023, similar results were observed. Grain fill was extended five days, maximum kernel dry weight increased 8%, and overall yield jumped 11 bushels per acre after applying a fungicide at R1.
Overall, this research highlights the potential for extended grain fill duration, kernel weight accumulation and higher yield when foliar disease is adequately controlled. In addition, this research provides further understanding of the influence on yield of extending grain fill and achieving maximum kernel weight. Put another way, it underscores the importance of maintaining and managing late-season corn plant health to improve grain fill duration and kernel weight accumulation.
However, it doesn’t address fungicide impact or lack of it when no disease is present. Foliar disease was observed in both years of this trial. Corn producers still should maintain informed and targeted foliar fungicide applications to maximize yield response and profitability, and to prevent fungicide resistance. That implies using rigorous scouting to spot disease and spray when necessary.
Source: Farm Progress