This may be a good time to put your sprayer in a safe place for the winter, unless you intend to spray for winter annual weeds after grain harvest. The most important thing is to clean it thoroughly before storage.

Many pesticides cause rapid corrosion of metal parts in the spraying system. Pesticides should be washed from the whole system immediately after use. Cleaning a sprayer thoroughly not only increases its life, but also reduces the chance of cross contamination of chemicals and prevents crop injury.

The cleaning solution used depends on the pesticide used. Always check the pesticide label for specific cleaning instructions. A solution containing 2 pounds of detergent for each 30 to 40 gallons of water is sufficient for removing most pesticides. First, flush sprayer with clean water. Then add the cleaning solution to the tank. Agitate thoroughly and allow the water-detergent solution to circulate through the system for several minutes. Remove nozzles and flush the system twice with clean water. Clean nozzle tips and screens in a strong detergent solution or kerosene, using a soft brush such as an old toothbrush.

Some pesticide combinations (especially if oil is used) may produce a putty-type paste (buttering out) in the tank. Flushing out the residuals of such chemicals after each load may prevent an accumulation. If water alone does not dissolve and remove the buildup, prepare a mixture of water and solvent such as kerosene, diesel fuel, or comparable light oil (1 gallon solvent for 25 gallons of water). Allow paste to dissolve, then agitate, and flush. Next, flush with detergent and clean water as explained in the previous paragraph.

After rinsing the equipment with an oil-based solvent or a water-detergent solution then rinse with one of the following in 25 gallons of water: 1 quart of household ammonia, or 1 cup of trisodium phosphate (TSP). Circulate this solution and let a small amount flow through the nozzles. Keep the remainder of the solution in the system approximately 6 hours (or overnight), and then pump it out through the nozzles. Finally, remove the nozzles, strainers, and flush the system twice with clean water.

Cleaning the outside of the sprayer components deserves equal attention. Remove compacted deposits with a bristle brush. Then flush the exterior parts of the equipment with water. A high pressure washer can be used.

When cleaning a sprayer, select an area where it will not contaminate water supplies, streams, crops, or other plants, and where puddles will not be accessible to children, pets, livestock, or wildlife. Preferably, the area should have a wash rack or cement apron with a well-designed sump to catch contaminated wash water and pesticides. Spray the rinse water and the cleaning solution on the same field where the pesticide was applied in a manner consistent with the intended use of the chemical. Avoid discharging the whole cleaning solution in a small area.

The quickest, easiest way to rinse a tank and spraying equipment and dispose of the waste safely is to carry a 25 to 50 gallon drum of fresh water with the spraying equipment. When spraying is finished, flush the system in the field. A concrete pad with a rinsate collection pit can be used to wash the interior and exterior of the sprayer without creating potential contamination of soil, ground water, and surface water. Most importantly, the concrete rinse pad also helps contain pesticides that are spilled on the sprayer or to the ground during loading or mixing.