There's no question that the use of unmanned aerial vehicles (UAVs), or "drones" have gained a lot of attention as a method of pesticide application in recent years. Within large-scale production agriculture, thus far UAVs have mostly been utilized for the application of fungicides. In many ways, this seems to be a natural fit as most fungicides are applied aerially and at ultra-low application volumes. But more recently there has been greater interest in the use of UAVs for the application of herbicides. As with everything there are advantages and disadvantages to this potential use, but I have no doubt that the industry will likely move (and is already moving) more in this direction. So, we need to be ready with answers but unfortunately, I think right now from a herbicide and weed management perspective, most weed scientists would say we are not there yet and probably still have more questions than answers. There is much more work that needs to be done to understand the effects of different drone application parameters on spray quality and weed control, and to determine which kind of herbicides and application timings may or may not be a good fit for a UAV application. We are doing some of this research here at the University of Missouri and sharing our initial results for people to see, and a variety of other excellent UAV application research is being conducted at other universities across the U.S.

However, it seems more often than not within our industry that the rate of adoption of a new practice or technology outpaces the speed with which we are able to generate research results and recommendations. And sometimes the rate of adoption of a practice may not be entirely consistent with the usage allowed on the herbicide label(s). As an example, I have had numerous drone applicators tell me that they have checked the label and that it is OK for them to apply a given herbicide with their UAV because it has an aerial label. I would classify that as "step 1" and almost always applicators have that information correct. But when I ask about the application volume/gallons per acre (GPA) that they are using, that's where things seem to start falling apart. Keep in mind just because a herbicide can be applied aerially doesn't mean that it can be applied at ultra-low application volumes (<5 GPA) like what commonly occurs with UAV applications. To that end, we have combed through a variety of herbicide labels and provide two tables for aerial application restrictions and parameters: Table 1 for common corn and soybean herbicides and Table 2 for common pasture herbicides. We aim to show: 1) what are some of the more common herbicides that are and are not allowed to be applied aerially, and 2) what is the minimum GPA allowed for an aerial application. These tables are not all-inclusive and are only provided as a guideline; be sure to carefully check and read through each herbicide label thoroughly before making any application with a UAV.

Aerial Application Restrictions and Parameters