Are You Smoking?

by Dennis R Gardisser, WRK of Arkansas LLC

Weather at the time and location of any spray application is essential. Careful monitoring of the weather during all applications is important for both knowledge of the event and possibly defense of an application, if it later scrutinized. Most agricultural aircraft have the ability to release a dollop of smoke by spraying a lightweight oil into the exhaust.

The use of smoke allows applicators to closely verify the exact direction of air movement throughout the duration of an application. The verification of velocity isn’t quite as exact. Applicators might not be able to determine minute differences in wind speed. By doing a daily observation over time and comparing that to actual measurements, applicators should easily be able to professionally estimate if the wind speed at the application site mimics recorded values closely.

By knowing the direction and speed, applicators may adjust as appropriate for any potential undesirable movement of their spray. This could result in leaving a larger buffer downwind or simply waiting for a time frame with a more desirable wind direction. This is just one of many tools an operator has at their disposal to mitigate any drift potential.

The use of smoke and observation results need to be recorded if the accuracy of any application is challenged. I’ve told many applicators, “If the use of smoke and the observation isn’t recorded – it didn’t happen.” This means that it is much more convincing to a regulator or, if you’re unlucky enough to be in civil proceedings, to a judge or jury, if the use of smoke is reflected on the job records. A simple statement of smoke use from applicators after the fact doesn’t seem to be as convincing.

With that in mind, the recommendation would be to include a check box or statement with VBS (Verified By Smoke) included on the weather observations placed on job tickets or records to reflect this application practice on every job. I have been told by some GPS manufacturers that they might be able to show a tic mark on log files to reflect smoke use in the future. At a minimum, weather records should show wind speed and direction at the start and finish of each application. Any major changes throughout the application should be noted as well. Smoke On!!

Gardisser received a bachelor’s degree in agricultural engineering in 1979, a master’s degree in 1981 and a PhD in 1992, all from the University of Arkansas. He is currently the president of WRK of Arkansas, an application technology and aviation insurance company. He has been inducted into the National Agricultural Aviation Hall of Fame and the Arkansas Aviation Hall of Fame.