Many parts of Iowa have had airplanes buzzing low over the ground applying fungicides during the last half of July and into early August this summer. The question is whether or not there will be a positive return with this application.
Tristan Mueller, manager of operations for the Iowa Soybean Association’s On-Farm Network, says corn and soybean producers need to check the costs when it comes to applying foliar fungicide. He provides the following information and explanation.
Total cost of fungicide and application is $15 to $30 per acre
First, let’s start with some simple math: the average cost of a fungicide is $10 to $15 per acre, the cost of application is $12 to $15 per acre for aerial and $5 to $8 per acre for ground. This brings the total cost of spraying the fungicide to between $15 and $30 per acre.
Next, an estimate of the crop cost needs to be figured in. Let’s be optimistic and say $3.50 for corn and $10 for soybeans. This means on corn, the farmer will need at least a 4.3 to 8.6 bushel-per-acre yield response from the fungicide to break even and a 1.5 to 3 bushel-per-acre response to break even on soybeans.
Finally, let’s analyze the likelihood of a fungicide having a return-on-investment in a drier year like we have experienced in some areas in 2016. Historically, both corn and soybeans have followed very similar trends for yield responses from fungicides. When the summers are drier like we are experiencing in some areas this year, disease pressure is lower therefore the yield response from a fungicide is typically smaller.
Potential payoff is much lower when conditions don’t favor disease
To illustrate this point, the graphs accompanying this article show the average response to fungicides tested with the Iowa Soybean Association (ISA) On-Farm Network since 2006. Keep in mind these graphs only show the average yield response. It is still possible for a fungicide to give a positive return-on-investment, but ISA On-Farm and Iowa State University testing shows that the probability is much lower when conditions are not favorable for disease.
Situations where the variety or hybrid is very susceptible to foliar diseases, such as northern leaf blight on corn, will increase the likelihood of a fungicide giving a positive return-on-investment. Look up the disease susceptibility or talk to your seed dealer to find out more information about your specific hybrid.
Another reason, besides yield, some farmers are spraying fungicides is to improve end-of-year standability of their corn in the field. The fungicide application may not add more bushels to the bin, but can make harvest go much smoother.
Leave some untreated strips in the field to and check results
It is good practice for farmers to leave some check strips during application to test how effective products or practices are on their operation. If applying a fungicide, leave some strips untreated and have the results analyzed by an unbiased organization. If interested in submitting trials to be analyzed, contact an ISA On-Farm regional field research specialist.