How to Test Pesticide Spray Technologies for Drift Reduction

Manufacturers interested in participating in the voluntary drift reduction technology (DRT) program can submit data to EPA. We prefer that applicants conduct their studies using EPA's test method, described below.

We will evaluate each data submission to verify the technology's drift reduction potential. If appropriate we will assign a drift-reduction star rating to the specific tested technology, based on the technology’s potential to reduce spray drift.  

Read more about EPA's review and rating of technologies.

Testing Protocol Available

With technical input from external experts, we have developed a protocol for testing pesticide application technologies for their potential reduction of spray drift.  DRT verification testing should be performed according to the Generic Verification Protocol for Testing Pesticide Application Spray Drift Reduction Technologies for Row and Field Crops

This protocol addresses three testing approaches:

  • Low speed wind tunnels (to simulate application by ground boom equipment).
  • High speed wind tunnels (to simulate application by aircraft).
  • Field testing (groundboom or aerial applications).

We anticipate that the testing of smaller technologies, such as spray nozzles and combinations of nozzles and drift-reducing adjuvants (an adjuvant is any substance separately added to a pesticide product--typically as part of a spray tank mixture--that will improve the performance of the pesticide product), would be conducted in wind tunnels that measure the amount of the relatively smallest driftable droplets produced by the technology under conditions of the test. Larger technologies, such as shielded sprayers, would be tested in field studies in which the amount of pesticide deposition from spray drift downwind from the edge of the field is measured. Manufacturers may also choose to use field studies for nozzles and adjvant-nozzle combinations.

In both types of studies, measurements of droplets or deposition are compared with those from a standard set of nozzles used in the study. The protocol describes the specific set of nozzles to use for the standard. Using a standard protocol with a standard set of nozzles as a baseline allows EPA to calculate comparison of drift reduction potential for each validated technology and across all validated technologies. We can use data from both wind tunnel and field tests in our risk assessments and therefore for risk management decisions for pesticides labeled for use with DRTs.

We limited the protocol to technologies for application to row and field crops because a large majority of agricultural pesticides are applied to these crops by ground boom and aerial equipment. Encouraging the use of DRTs for these uses should have an overall greater benefit to drift reduction. In the future, we may consider expanding this voluntary program to application technologies for orchard and vineyard crops, which require the use of significantly different application equipment (e.g., air blast sprayers).

Technology manufacturers should contract with a qualified testing facility capable of performing these tests with the appropriate equipment, methods and quality control standards. Refer to the protocol, section A8, Special Training and Certifications, for further information. Also, we strongly recommend those who plan to conduct a field study to contact us in advance so we can review the field study protocol, since such studies are complex and expensive.