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Does a Foliar Fungicide Application Increase Grain Corn Moisture?

In previous CropPest Ontario issues ( July 17, 2009 - "Factors to Consider in Your Corn Fungicide Decision!" and July 31, 2009 - "Lodging (Stalk Rot) and Corn Fungicides") we discussed corn fungicide trials conducted in 2008 (and again in 2009) by the University of Guelph Ridgetown Campus and OMAFRA. In these articles we discussed corn fungicides interactions with hybrids as well as their impact on stalk rot/standability. This time we will present 2008 data which showed an association between increased grain moisture and a fungicide application (Headline) at the tassel to silking stage in 21-hybrid trial (Figure 1). Due to limited space and resources we did not apply any other fungicides in this trial.

Figure 1 shows the individual hybrid grain moistures as compared to the untreated check at the Ridgetown Campus location. When all three locations (Ridgetown, Belmont and Wingham) were combined, we found the application of HEADLINE increased average grain moisture across hybrids by 1.2%. The effect on grain moisture depended on the hybrid, with some hybrids showing no differences while several others were approximately 4.0% higher in grain moisture at harvest compared to the untreated check.

The higher grain moistures associated with certain hybrids could be attributed to longer stay green among hybrids associated with strobilurin fungicides (such as Headline and Quadris).

Does a fungicide application delay physiological maturity? We have no evidence that indicates a delay in physiological maturity beyond the rating of the hybrid. In high disease environments however, maturity may be delayed where leaf diseases were controlled with a fungicide application. In this case, grain moistures may be higher with a fungicide application, but they are usually accompanied with significant yield gains (but not always). For example, Hybrid 21 in Ridgetown was 4% higher in moisture at harvest, but yielded 35 bu/ac higher with much better standability compared to the same hybrid where no fungicide was applied. Our other work in high disease environments (inoculated trials) support this observation as well. Keep this in mind as we approach harvest.

This project was funded through AAC CanAdvance Program, Ontario Corn Producers Association, BASF, OMAFRA, and University of Guelph Ridgetown Campus.