If you haven’t winterized your pesticide spray equipment, you better hurry up.
A little maintenance now could save you a lot of money next spring. You should also consider how you will store your unused pesticides to ensure they will be effective next year.
First, the outside of a sprayer should be washed, while also rinsing spray tanks. Spray tanks can be rinsed by circulating water through the spray system.
Add water up to 10% of spray tank capacity and spray on a labeled site. Solutions rinsed/drained from spray equipment, or rinsates, contain herbicide residues.
Select a location to clean equipment where any spilled rinsate will not contaminate water supplies, streams, crops or other plants and where puddles will not be accessible to humans, pets, livestock, or wildlife.
If a facility to catch and/or contain the rinsate is not available, spray the rinse water or the cleaning solution on a site and in a manner consistent with the label use of the herbicide.
Many pesticide product labels will recommend adding select cleaning agents to spray tanks to aid in removing water and oil soluble pesticides.
Detergents, ammonia or approved commercial tank cleaners are required to remove many herbicides from spray equipment. Be sure to follow label recommendations.
• Dry-formulated household detergent mixed with water can adequately remove some herbicides.
• Ammonia increases the pH of the solution, which increases solubility of some herbicides and the potential to remove them from the spray tank.
• Commercial tank cleaners are recommended for some oil- and water-soluble herbicides. These cleaners generally raise the pH of the solution and act as detergents.
Nozzles, screens, and strainers should be removed and cleaned separately in a bucket containing water and the recommended cleaning agent once tanks have been cleaned. Remember, bleach should never be mixed with ammonia as this creates a deadly chlorine gas.
When cleaning herbicide-contaminated equipment, wear the same personal protective equipment (PPE) that the labeling requires for making applications, plus a chemical-resistant apron or other appropriate protective equipment. Also wear eye protection, even if not required by the label directions.
To protect sprayer pumps and lines from corrosion and freezing damage over the winter months, circulate antifreeze through entire sprayer.
A 50/50 mixture of antifreeze and water should be pumped through system for at least 5 minutes. With the antifreeze mixture still in the system remove some components:
• Remove pressure gauges and check valves. Store them in marked container at room temperature over the winter to avoid damage from freezing temperatures. Plug assemblies.
• Nozzles and screens should be removed and placed into a marked container filled with lightweight oil (kerosene or diesel fuel). Correctly plug these assemblies as well.
By capping assemblies, remaining antifreeze will ensure that lines don’t freeze and crack.
Antifreeze should remain in sprayer through winter months to avoid air moisture from corroding internal components of sprayer.
Sprayer should be ready for storage in a sheltered location away from liquid and dry fertilizers which will corrode paint and hardware.
How should you store your unused pesticides? Dry formulations (ex. granular and wettable powders) are not generally impacted by freezing but should be stored in a dry location.
Liquid pesticides may freeze and result in separation of the active ingredients from carriers, which could reduce effectiveness of pesticide product.
This reaction may include coagulation or crystallization which may cause further plugging of spray lines. Some frozen pesticide products often retain effectiveness if applicators follow steps when thawing and re-dissolving the suspension.
Pesticide products have different freezing temperatures due to the presence of hydrocarbon solvents in many formulations. Hydrocarbon solvents actually reduce the freezing point below 32 degrees F.
Pesticide product labels often explain a pesticides minimum storage temperature, in addition to whether:
1) freezing poses a problem
2) active ingredients separate from carriers if frozen
3) effectiveness of a pesticide is reduced if frozen
4) the active ingredients and inert ingredients go back into suspension. For more information on storage of specific pesticides read the label or go to: http://www.pesticides.montana.edu/Reference/Coldweatherstoragemt8706.pdf
Source: Cold Weather Storage and Handling of Liquid Pesticides, by Greg Johnson, Pesticide Education Specialist, and Robert Hendrickson, Program Assistant
