Regulatory requirements and experimental field design

DFR studies are designed and conducted to describe the decline profile of the active ingredient on foliage and/or soil surfaces when applications are made at the proposed label rate. These surfaces are limited to those which can be touched or disturbed by workers and from which residues can be dislodged, deposited on human skin and clothing, or inhaled during the performance of field work and harvesting operations. 

Important factors need to be considered to design a DPR study  

Type of application equipment used for example, using over-the-top spray boom or air blast for grapes. The sprayer should be consistent with local cultural practices for each test site. 

Timing applications should be made at the time of the year and plant growth stage where potential worker exposure would be at a maximum. It is critical to have a mature crop because exposure will be increased owing to the larger surface area of the foliage compared with that of an immature crop. 

Applications should be made when the activity of field workers will result in maximum exposure (i.e., pruning, girdling, harvesting, etc.) 

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