In 2024, a Wisconsin corn grower found a tar spot infestation in his corn field and called Dairyland Aviation to make a fungicide application. The timing was tricky — already late August — and the applicator was skeptical the application would work nearly two weeks after the R4 growth stage. The farmer and the applicator agreed to roll the dice and make the application with a control strip to analyze its effectiveness.
Between the treated field and the untreated strip there were 15 bu. to 20 bu. more.
Despite being outside the optimum window for disease control, this field trial yielded strong results.
From an aerial view, there was a clear line between the treated and untreated parts of the field. Within the canopy, the treated rows were clearly delineated from the untreated.
Since 2018 when tar spot was identified as a widespread epidemic in the Midwest, many crop protection companies, applicators and farmers have explored different ways to protect corn yields from the disease. Tar spot infestations are heavily weather dependent, and the disease thrives in cool temperatures between 60 F and 70 F, with high humidity.
The disease has been either confirmed or reported in Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kentucky, Maryland, Michigan, Minnesota, Missouri, Nebraska, New York, North Dakota, Ohio, Pennsylvania, South Dakota, Virginia and Wisconsin.
The National Agricultural Aviation Association details how the above case study used an 800-gal. turbine-powered airplane, guided by a state-of-the-art GPS, at an application rate of 2 gal. of spray per acre. The aircraft’s spray boom used a pulse width modulation nozzle control system — similar to those equipped on ground sprayers.
You can find an aerial applicator near you via the National Agricultural Aviation.
