Fungicide Use in Corn
The majority of university plant pathologists continue to contend that foliar fungicide applications to corn should be driven by the hybrid’s resistance to foliar diseases, amount of disease present on the corn leaves, and risk factors for the disease pressure increasing after the tasseling (VT) stage.
On the other side of the question of whether a fungicide should be applied to corn are the crop protection manufacturers of fungicides. The argument of pro and con about fungicide use between university researchers and fungicide companies has continued for years, and both sides appear to be armed with research data that supports their arguments.
Carl Bradley, Department of Crop Science, University of Illinois, in speaking to attendees of the University of Missouri Crop Management Conference, said he looks at fungicide use as a tool that should increase yields enough to more than pay for the cost of the fungicide and application. In this day of higher corn prices, that increase in yield doesn’t have to be much of an increase compared to a few years ago when corn prices were much lower.
“For foliar disease control and yield response, we tend to see more consistent profitability when fungicides are applied because of a disease threat,” Bradley said.
From Illinois research run the last five years, he said, “Less than one-half of the time we would have been profitable when spraying fields that had a relatively low level of disease.” These results are most applicable when the hybrid is resistant to disease and especially gray leaf spot.
The main discussion about fungicide use on corn is for an application between the VT and brown silk (R2) stage late in the growing season.
If a corn field is sprayed with a foliar fungicide and there is little or no disease present, but a yield bump occurs, then the fungicide is having an affect other than disease control on the plant. “There are some other factors that can occur with these fungicides that are not related to disease control,” Bradley said.
Crop protection companies and ag retailers have been able to convince a growing percentage of corn growers to use a fungicide application because there have been yield bumps unrelated to disease. BASF was the first company to heavily promote the VT to R2 fungicide application based on protecting “plant health.”
Last fall BASF came out with new study results it claims showcase the plant health benefits of fungicides and its F500 active ingredient component. Protecting a corn plant’s efficient photosynthesis, according to the research, drives increased yields.