You probably won’t use your sprayer again until next spring. To avoid potential problems, frustration, and major headaches next year, it’s wise to give your sprayer some TLC (Tender Loving Care) this time of year. While there may still be other important matters demanding your attention, don’t forget to winterize your sprayer. Don’t delay if you haven’t done so already. You want to prevent a cracked pump or reduced efficiency caused by not properly winterizing before temperatures drop below freezing. Here are some essential steps to take with your sprayer now.

Rinsing
You probably did the right thing when you last used the sprayer: thoroughly rinsed the entire system (tank, hoses, filters, nozzles). If you didn’t, be sure to do this before storing the sprayer. An unrinsed sprayer after each use, especially after the spraying season ends, can lead to cross-contamination of products applied to different crops next spring. Pay special attention to avoiding cross-contamination, which can cause severe crop damage, especially when using some of the newer 2,4-D and Dicamba herbicides. Another issue caused by not properly rinsing all sprayer parts is clogged nozzles. Once nozzles are clogged and remain that way for a long time, it becomes difficult to restore them to their normal working condition, which is what you expect from a properly cleaned nozzle. Leaving chemical residues in nozzles often causes changes in flow rate and spray pattern, resulting in uneven chemical distribution on the target.

The ease of properly rinsing a tank’s interior depends on its type. It is very simple if the tank is relatively new and has special rinsing nozzles and mechanisms inside. If not, manual rinsing becomes more difficult and can pose safety risks, such as inhaling fumes from leftover chemicals during the process. To avoid these issues, you can either replace the tank with one that has interior rinse nozzles or install an interior rinse system in your current tank.

For effective rinsing of all sprayer parts, circulate clean water through the entire sprayer for several minutes first with the nozzles off, then flush out the rinsate through the nozzles. Rinsing should ideally be done in the field or on a concrete chemical mixing/loading pad with a sump to recover rinse water. In any case, dispose of the rinsate following the instructions on the pesticide labels you have used. Always check the label for specific directions. Most labels recommend the following procedure: if rinsing on a concrete rinse pad with a sump, return the collected rinsate to the tank, dilute it with water, and spray it in the field where it cannot reach ditches or other water bodies. If rinsing is done in the field, make sure you are not flushing rinsate in one area. It’s best to dilute the rinse water in the tank further and spray it on the field in places where it won’t contaminate nearby water bodies or ditches.

Cleaning
Rinsing the system with water, as explained earlier, may not completely remove chemicals from the sprayer. This could lead to cross-contamination issues. Residues of certain pesticides left in the sprayer might cause serious problems when applying a spray mixture containing those residues to a crop highly sensitive to that pesticide. To prevent such issues, it’s best to thoroughly clean and rinse the entire spraying system with a cleaning solution. Usually, a mixture of 1 part household ammonia to 100 parts water works well for cleaning the tank. However, if the tank hasn’t been cleaned for weeks or immediately after the last spraying, you might need to start with a detergent solution. Some chemicals require specific rinsing solutions. Always check the product label for the latest cleaning instructions.

Cleaning the outside of 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 if available. Wash the exterior of the equipment either in the field, away from ditches and nearby water sources, or on a specially constructed concrete rinse pad with a sump. Again, the rinsate should be disposed of according to the label recommendations. As I mentioned earlier, most labels recommend the same practice: put the rinsate collected in the sump back into the tank, dilute it with water, and spray it in the field where there is no potential for the rinsate to reach ditches or other nearby water bodies.

Inspecting sprayer during winterization.

Winterizing
Recheck to ensure no liquid remains inside any of the sprayer parts to prevent freezing. The pump, as the core of a sprayer, needs special attention. You don’t want a cracked pump or one that isn’t working properly due to inadequate winterization before temperatures drop below freezing. After draining the water, add a small amount of oil, then turn the pump four or five revolutions by hand to coat the inside. Ensure this oil won’t harm rubber rollers in a roller pump or rubber parts in a diaphragm pump. Refer to the operator’s manual. If oil isn’t recommended, pouring one tablespoon of radiator rust inhibitor into the pump’s inlet and outlet can also help prevent corrosion. Alternatively, use automotive antifreeze with rust inhibitor in the pump and other sprayer parts. This helps protect against corrosion and freezing if any water remains. To prevent corrosion, remove nozzle tips and strainers, dry them thoroughly, and store them somewhere dry. Another option is to submerge them in a can of light oil, such as diesel fuel or kerosene.

Storage
Find ways to protect your sprayer from the harmful effects of snow, rain, sun, and strong winds. Moisture in the air, whether from snow, rain, or soil, causes rust on the metal parts of all types of unprotected equipment. This is especially true for a sprayer, which has various hoses, rubber gaskets, and plastic components. While the sun can help reduce moisture in the air, it can also cause damage. Ultraviolet light weakens and softens rubber parts like hoses and tires, and degrades some tank materials. The best way to protect your sprayer is to store it in a dry building. Keeping sprayers inside also allows you to work on them anytime during the off-season, regardless of the weather. If storing inside isn’t possible, cover the sprayer with a material that shields it from sun, rain, and snow. For trailer-style sprayers, place blocks under the frame or axle and reduce tire pressure during storage.

Finally, double-check all sprayer parts before leaving it behind. Identify parts that may need repairs or replacement. Inspect the tank and hoses for any signs of cracks or damage. Check the painted surfaces for scratches and touch up with paint to prevent corrosion. Also, remember to cover openings to prevent birds from nesting in the sprayer and to keep insects, dirt, and other debris out of the system.

Erdal Ozkan
Professor and Extension State Specialist
The Ohio State University