Disease & Pest Management

When Ron Roling first implemented drone applications in his 2020 northeast Iowa hybrid trials, he was curious to see how this relatively new technology would perform in real field applications. Roling implemented the drone technology while he was testing the efficacy of various fungicides, micronutrients and biologicals. 

Now, four seasons in, the AgriGold regional agronomist has been able to not only evaluate how AgriGold hybrids respond to products, but also the value of using drone applications within these product categories. 

“Initially, we designed these trials to test fungicide impact on tar spot,” Roling says. “While none of our locations have had the right conditions for the disease, we were able to take a look at a number of other factors when evaluating these trials, including yield impacts of fungicides with no disease presence.” 

Key Takeaways: 

  • Drones can help improve the timing and flexibility of fungicide applications. 
  • Hybrid response to fungicides is based on a number of factors. 
  • Biological performance can vary based on existing field conditions.

The Drones

In Roling’s trials, spraying typically took place at VT or R1 growth stages, while some applications expanded the timeline into R2. Like other application options, there are pros and cons to drone use.

“I wanted to see the coverage a drone would give us as an alternate application method,” Roling says. “With drones, you’re getting closer to the canopy at a slower speed than aerial applications, whether you’re using an airplane or helicopter.” 

Ultimately, he was really impressed with the coverage. It exceeded expectations and was almost equivalent to a ground rig at high volume. 

Roling admitted that drones lack the ability to cover volume with speed like aerial applications, but noted they are getting more capacity all the time. Plus, they open doors for getting in the fields when other options cannot. 

“Drones have the ability to get into spots even airplanes or helicopters can’t because they are flying so much closer to the canopy,” he says. “If you have a saturated field and can’t get your ground rig in, the ability to use a drone will give you solid coverage in a timely manner.” 

Overall, Roling sees drones as another tool in the application toolbox for foliar applications involving fungicides, biologicals and micronutrients.

The Fungicides

While the trial’s intent was to measure efficacy with tar spot, the plots’ dry conditions were not favorable for that specific disease. Roling instead kept the trial applications going and looked at individual hybrid responses to fungicides with or without diseases, as well as the fungicide response with and without disease pressure.

“There are certain hybrids that will give you an ROI from a fungicide treatment regardless of disease pressure,” Roling says. “Knowing how our hybrids will react helps us inform our customers of whether to spray or not when disease pressure is not yet present.” 

The trials also compared brand-name fungicides and generics when disease pressure was present. Overall, Roling noted the higher value fungicide will provide more benefit than generics with disease pressure present.  

As for which product to use where, Roling recommends talking with your local AgriGold representative to identify which hybrids and conditions would benefit the most from fungicide applications.


Multi-Year R1 Fungicide Results:

Disclaimer: Performance may vary from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.


The drone trials also included biologicals. However, the takeaways were not as clear as those with fungicides. Roling noted that results varied greatly based on management and fertility, leaving recommendations vague at this time. 

“We had some situations where biologicals all worked really well, giving a good return on investment,” he says. “But we had others where none of them performed.” 

Roling’s advice? Growers with high-management, high-fertility systems will likely see the biggest return on investment. But growers interested in trying biologicals can still test them in their operation. 


Another area where drones open doors is within micronutrient application. AgriGold supports in-season decision-making through a robust tissue sampling program. Growers looking to achieve high yields can use the sampling to understand if they need those micronutrients and when. 

“The drone gives some flexibility in micronutrient application since it’s more quick-turn than aerial applications,” Roling says. “Compared to ground rigs in saturated fields or hilly terrain, the drone opens up some stability, because of its ability to get closer to the canopy and actually enter the field.” 

Like with biologicals, the results of the micronutrient trials varied based on a given field’s approach. 

Overall, Roling notes that drones are yet another strategy growers should consider using throughout the season. Roling doesn’t view application choices as an either/or scenario. Rather, each has its place given varying circumstances. 

“These drones are just another tool,” he says. “It doesn’t have to be the only tool. Each has its advantages.”

Growers interested in learning more about how AgriGold hybrids react to fungicides, biologicals and micronutrients can reach out to their local agronomist.