WEST LAFAYETTE, Ind. — Using fungicides to increase corn yield may only pay off if a crop already has signs of a fungal disease or is at high risk to get one, according to a Purdue University expert.
Kiersten Wise, an Extension specialist in field crop diseases, said fungicides have the best chance to increase yield when fungal diseases are, or have a high risk of, infecting a crop.
But Purdue studies in 2008 showed that yield wasn’t increased enough to make use of fungicides profitable in crops that seemed healthy.
“It doesn’t pay in every situation. In situations where we have resistant hybrids or where corn was planted after soybeans, we don’t tend to see a higher yield,” Wise said.
“Even if you see a few extra bushels over an acre with fungicide application, that may not be enough to pay for the application based on the price of corn.”
As the price of corn has dropped back toward $4 per bushel, it takes more bushels to cancel out the cost of applying a fungicide.
On healthy crops, Wise said, it might not be a good investment, especially when application costs are high.
For instance, if the application costs were $28 per acre, an additional seven bushels of corn per acre would be needed just to break even at $4 per bushel.
Wise suggested checking crops regularly to see if fungal diseases are present before deciding on fungicides.
“The only way you can know if a disease is reaching a threshold is to get out there and scout,” Wise said.
The greatest risk of fungal disease infection in corn is in fields where corn was planted the year before, hybrids susceptible to fungal diseases, crops that are planted late and poor weather conditions.
Wise said another Purdue study she was involved in did not show an increase in soybean yield when a fungicide was used in 2008.
Disease pressure was low in this study, so researchers could not determine how the fungicides might have helped in soybeans with disease problems.