Managing Pesticide Applications for Me and the Environment

2018 Crop Production Clinic Proceedings

Managing Pesticide Applications for Me and the Environment

Pesticide applications dominate today’s agricultural landscape. These applications are critical for mitigating yield loss and managing a wide variety of pests. In today’s environment, it is critical that pesticide applicators focus on both managing the pest as well as mitigating environmental impact to non-target areas or non-target organisms. Balancing the two pieces is difficult and has created a dynamic which is changing the way pesticide labels are written and the way we approach pesticide applications.

In 2017 a significant number of cases of off-target movement from pesticide applications were reported. For example, damage from dicamba was reported on 3.6 million acres of soybeans. Despite having vague, abstract, and inconclusive evidence on why so much off-target movement occurred, many theories have been postulated in the media and other agricultural information outlets. Having an equal or greater number of off-target cases next year could jeopardize the reregistration of dicamba as well as the registration and reregistration of future pesticides. It is critical that both private and commercial applicators recognize their value in the continued availability of crop production products in the agricultural industry.

If we look at where we are, it is imperative to recognize that the pesticide application process is complicated and it is difficult to point to any one thing as the overwhelming problem. While it is cliché to say “the pesticide label is the law,” it is important to recognize that the pesticide label is not only a recommendation, but a document that the user is legally obligated to follow. In regards to dicamba, it is easy to point out that volatility is a contributing factor of the off-target movement that occurred in 2017, but a closer look will clearly show that there are many other things that also contributed to the problems we observed.

An in-depth analysis will highlight that pesticides can move away from the intended target area in a myriad of ways. There are two types of pesticide drift: physical particle drift and vapor drift. Physical particle drift is associated with the movement of spray particles away from the intended application site at or near the time of application prior to the particle depositing in the target area. Vapor drift is when the pesticide turns to a gas and then moves away from the target area after it has deposited in the intended application area. Both forms of drift have the potential to cause injury to susceptible vegetation, wildlife, and people.

The consequences of pesticide drift can be quite significant. In the last two years, there have been numerous incidents of dicamba damage from dicamba, particularly on soybean. In 2017 alone, there was 3.6 million acres of dicamba damage reported by Kevin Bradley on soybean nationally. Vapor drift has been a primary culprit that many have pointed to the challenges that have occurred. However, with a closer look at the situation it becomes evident that off-target movement occurred because of a wide range of things including but not limited to tank-contamination, physical particle drift, vapor drift, and temperature inversions.

With the newly registered products, the labels included extremely specific guidelines on how to apply the products. While the extensive label restrictions appear to be cumbersome to applications, it is critical to follow the restrictive guidelines. The restrictions, in many cases, directly address the major factors that contribute to tank-contamination, physical particle drift, vapor drift, and temperature inversions. These label recommendations for the new dicamba formulations provide good recommendations for applying all pesticides in terms of reducing off-target movement as they address the primary underlying principles for off-target movement.

Most of the guidelines for reducing pesticide drift are targeted toward physical particle drift because it is usually a larger contributor to off-target movement than vapor drift and the applicator has greater ability to reduce physical particle drift than vapor drift. A few examples of this can be seen in the pesticide labels for Engenia, Xtendimax, and FeXapan. One of the biggest contributors to physical particle drift is wind speed and direction. The labels of these products address this by having a maximum wind speed of 10 mph in which applications can be made and also have language restricting and/or prohibiting applications when the winds are blowing toward certain sensitive crops or habitats. The labels also specify a maximum boom height of 24 inches because increasing boom height increases the potential for physical particle drift. They address distance to sensitive crop habitats through the use of buffer zones, recognizing that greater buffer distances reduce the potential for products to end up in those same sensitive areas.

The most extensive area where the new labels focus in terms of physical particle drift reduction is droplet size. It is well known that the larger the droplet, the lower the potential for off-target movement. The labels have been written to ensure that applicators use nozzles, pressures, and tank-solutions that will have a low propensity for physical particle drift. Applicators should adhere strictly to these label restrictions to minimize the drift that could occur from using these products.

Pesticide drift, including that from dicamba over the top of dicamba-tolerant crops, is a responsibility of the applicator and all others involved in the crop protection industry. Adhering to basic principles of drift reduction is a good practice not only for dicamba, but for all pesticides. However, applicators should take care to make sure they are balancing management of off-target movement with the performance of the pesticide.