Avoid Getting Burned by Herbicide Residues

Herbicide residues in the tank can cause devastating yield losses:

Even if the sprayer has been "rinsed out" with water the addition of surfactants or liquid fertilizers (eg. AGRAL 90, 28% UAN) to the next tank load may cause inadvertent loosening of previous residues. For example, applying a fungicide like "Folicur" to a wheat crop following an application of a corn herbicide (i.e. Accent, Option, and Ultim) has caused severe yield losses due to an incomplete sprayer cleanout procedure. Therefore the following pointers, along with information specified on the product label should be used to minimize the risk of contamination.

General tank clean out steps:

1. Before cleaning the sprayer, dispose of surplus spray solution. The Grower Pesticide Safety Course suggests diluting the remaining spray solution with water at a 1:10 ratio. This diluted solution can be applied to the previously treated area provided that the maximum recommended product rate on the label is not exceeded.
   
2. Fill tank with water and add detergent, ammonia or other tank cleaner products (See table 1) and allow agitate vigorously for 10-20 minutes.
3. Flush the boom, hoses and nozzles with solution. Be sure to operate every circuit in the pumping system. Flush each boom section individually with full liquid flow. Important: When flushing the boom, open the boom ends to blow out particles and spray solution from the line. Drain tank.
   
4. Wash out any self-cleaning filters or strainers using your cleaning solution.
5. Wash outside of sprayer with soap and water.
6. Remove all screens, nozzles and wash separately in a bucket containing cleaning solution. Wash out any measuring containers with the cleaning solution.
7. Thoroughly rinse tank, booms, hoses, strainer and pump. These parts are often overlooked and can trap residues. Because of today's highly active, low-use-rate herbicides, it is essential to clean out every trace of herbicide.

General Precautions:

• Wash water contains herbicide residues. Never allow wash water to run into any water source (i.e. a well, pond, lake).
• Do not leave puddles that may be accessible to children, pets, farm animals or wildlife.

Choose the right cleaner:

Each herbicide should have a recommended cleaning agent listed on the product label. The following table summarizes herbicide-specific cleaning agents found after several hours of combing through product labels. This is by no means a comprehensive list and therefore the pesticide label should always be consulted.

What if the label doesn't specify a cleaning agent or a cleanout procedure?

Some product labels simply don't state a cleanout procedure. In that case, the 7 step cleanout procedure above along with one of the three "cleaning solutions" listed would be acceptable. For "group II" products like Pursuit, the preferred cleaning agent is household ammonia, according to the manufacturer.

Cleaning Solutions

• Clean water rinse (i.e. triple rinse)
• Ammonia solution at 3%/100L water
• Strong detergent solution (i.e. 1.0 kg detergent/150 L water)

Warning: Do not mix ammonia with chlorine bleach. This can produce toxic chlorine gas.

Table 1. Recommended tank-cleaning agent for several herbicides used in Ontario

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