Submitted by Jeanette Gaultier, MAFRD Pesticides Specialist
Crop injury caused by improperly cleaned sprayers accounted for 5 to 15 percent of total pesticide incidents reported to MAFRD over the past three years (see chart below). The acceptable number should be 0%, since injury caused by tank contamination is completely avoidable!
Herbicides effective at low concentrations, such as group 2 herbicides, are the usual suspects. Improper clean out of group 14 herbicides, which also work at low concentrations and are increasing in use, are partly responsible for the 3X rise in tank contamination injury between 2012 and 2014. However, even low levels of other herbicide groups (e.g. group 4s) can cause injury to sensitive crops.
So, while cleaning is not the most fun job on the farm, it’s important (just like mom said). Follow these tips, from page 15 of the 2015 Guide to Field Crop Protection, to achieve a clean sprayer (www.gov.mb.ca/agriculture/crops/guides-and-publications/pubs/crop-protection-guide-intro.pdf):
- Clean your equipment as soon as possible after application. Sprayers should be cleaned at the end of an application, at the end of the day or when switching products (whichever comes first).
- Use the appropriate cleaning method. Cleaning usually begins and ends with water rinses, with an ammonia, a detergent (may include surfactants), or a water rinse in between. Refer to the Guide to Crop Protection or the product label for directions. Rule of thumb for products that don’t list a method: use water for water soluble formulations, detergent for EC, SC or flowable formulations and ammonia for less soluble products.
- Don’t rush. Allow water to circulate for at least 10 minutes, ammonia for 15 minutes and detergent for 5 minutes. Some labels may recommend leaving a rinse in the tank for a few hours or overnight, if possible.
- Remember the nozzles. Run the rinse through the boom and nozzles for about 5 minutes. Take an extra few minutes to inspect your nozzles and screens. New pesticide formulations are less likely to collect on screens but suspended particles or algae in water can also be culprits.
The first rinse of a sprayer is best disposed of by applying in the field that was treated. Further rinses should be disposed of in locations away from water and other sensitive areas.