By Gared Shaffer, SDSU Extension Weeds Field Specialist

With the introduction of many new plant growth regulator herbicides, such as dicamba-based, and 2,4D choline products, sprayer system cleanout has become even more critical before spraying resumes this growing season. Research has shown that it is impossible to remove all dicamba or 2,4-D residues from a sprayer with only water. Herbicides can form deposits in the spray tank, screens, filters, nozzles, end caps and other parts of the plumbing system. For example, if dicamba or 2,4-D residues are present in a tank of Roundup or Liberty herbicide and is sprayed on non-dicamba tolerant soybeans the surfactant in Liberty can act like a powerful tank cleaner and could create a byproduct that can injure sensitive crops.

Procedure to Clean Dicamba Out of a Sprayer

New Restricted Use Pesticides (RUP) dicamba labels require following cleanout procedures.

  1. After last application, drain sprayer immediately including boom and lines. Do not allow spray residues remain in the spray boom lines over night or for extended period of times before flushing.
  2. Flush tank, hoses, boom and nozzles with clean water. If equipped, open boom ends and flush.
  3. Clean and inspect all strainers, screens and filters. 
  4. Using a cleaning solution containing a strong detergent recommended by the equipment manufacturer, mix enough solution to wash entire spray system inside and out, including all surfaces in the tank. 
  5. With cleaning solution in tank. Start spray tank agitation system and thoroughly recirculate cleaning solution for at least 15 minutes. 
  6. Repeat washing all parts of the tank, including all surfaces of the tank, including the top surface. 
  7. Flush hoses, spray lines and nozzles with cleaning solution for at least one minute. 
  8. Remove nozzles, screens and strainers and clean them separately in cleaning solution after completing the above procedures. 
  9. Drain pump, filters and lines.
  10. Rinse the interior AND exterior of the entire spray system, including the boom with clean water.