Applying Miravis® Neo fungicide provided economically advantageous yield responses at several sites despite low disease pressure and abnormally dry conditions.
R1 fungicide applications provided the most consistent response in low disease environments.
Conditions more conducive to early disease development will likely result in more response from multiple applications.
Introduction
Foliar fungicide applications can be an effective way to protect and improve corn yield potential. Yield increases can be the result of protection from diseases or plant health benefits that help withstand stress. The most successful disease management programs require proactive fungicide applications at first sign of or just before symptoms develop. In addition, diseases such as tar spot can develop almost anytime throughout the corn reproductive stages. Due to this, early application timings may not have enough residual to provide protection all the way up to corn maturity. The ability of some diseases to rapidly develop at various times has increased interest in better understanding when and what value can be generated with multiple fungicide applications in comparison to a single timing.
Fungicide Application Timing Trials
Fungicide trials were established across the Corn Belt by the Agronomy in Action Research Team in hopes of comparing single and multiple fungicide application under natural disease complexes such as tar spot. This trial compared the following fungicide programs:
Xyway® LFR® fungicide (15.2 oz/ac) applied at planting in a 2×2 placement
Miravis Neo fungicide (13.7 oz/ac) at R1 timing
Miravis Neo fungicide at V12 timing (13.7 oz/ac) and at R1
Xyway LFR fungicide (15.2 oz/ac) applied at planting followed by Miravis Neo fungicide (13.7 oz/ac) at R1
Xyway LFR fungicide (15.2 oz/ac) applied at planting followed by Miravis Neo fungicide (13.7 oz/ac) at V12 and R1 timings
No fungicide, check comparison.
At planting applications were applied with a 2x2 placement attachment on research planters as specified with fungicide labels. Mid-season V12 applications were applied to specified plots using a calibrated hand boom.Late-season R1 foliar applications were made using a drone equipped with a boomless controlled droplet atomizer system to creates more consistent droplet sizes than flat fan nozzles (Figure 1). Overall disease pressure was low across trial sites with minimal symptoms appearing near corn physiological maturity.
Trial Results
Results from this trial showed an average yield increase of 10.6 bu/ac with a single-pass fungicide application at the R1 growth stage in nine of ten trials (Table 1). Responses ranged from 0 to 19.2 bu/ac depending on trial site, although only two of the nine trials were statistically significant. Minimal disease symptoms were observed at locations throughout the season, indicating that positive yield trends were more likely result of increased plant health. Six of the nine sites had a statistical increase in yield from one or more of the individual fungicide treatments. These more responsive sites were averaged together and analyzed for differences among individual timings (Graph 1). There was no yield advantage of additional applications beyond the single R1 timing when averaged across responsive locations, likely due to low disease presence. Xyway LFR fungicide alone did improve yield over the no fungicide, check but yielded less than any Miravis Neo fungicide treatment. It is also unclear from this trial how much protection Xyway LFR fungicide would provide under late season disease progression if present.
Lower disease pressure and drier than normal conditions across all sites likely contributed to the lack of differences between fungicide treatments. There may be situations where a second fungicide application during grain fill may be warranted due to significant late-season pressure. In these situations, relative risk of late disease development based on presence of conducive conditions for disease development in a specific area should be considered before applying. Applying fungicide products that contain multiple active ingredients, like Miravis Neo fungicide and Trivapro® fungicide, can offer a better chance of disease control compared to single active ingredient fungicides.
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