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I can say with much certainty that many of the ideas we promote are not just necessity, but matters of convenience and efficiency. For example, a sprayer that is cleaned up immediately after spraying is a lot easier to clean than one that is left to sit and dry out for some time before we finally decide to make time to rinse it and clean it up. Those repairs that we know are needed are also just so much easier and safer to accomplish with a clean sprayer too. Not only are they easier, but they prevent you from wasted time and questions about why the thing just isn't working properly the next time you go to the field.

For example. foam marker solution that has been drained from the tank doesn't have the same properties as the original concentrate, so if you intend to keep the already diluted solution, it may be a good idea to mark the original container as 'Already Diluted.' Consider just pitching (meaning proper disposal of) that last half gallon of foam marker mixture. We spent an hour or two trying to make twice diluted foam marker solution make foam at the ends of the boom. We could hear the pump pumping and we could tell we were getting pressure. We were even getting some liquid to come out of the marker, but there was no way we were going to make any foam. By the time we figured out what had happened, I'd already stepped off the first field with flags and missed the prime spraying weather the first day out.

Anyway, whenever you reach the point that you're fairly certain you won't be going back to the field for any kind of re-spray, take some time to make those repairs, but start with a good thorough cleanup procedure. The following cleaning procedure is recommended for all herbicides unless more specific instructions are listed on the label.

Cleaning

Add one-half tank of fresh water; flush tanks, lines, booms and nozzles for at least five minutes using a combination of agitation and spraying. Rinsate sprayed through the booms is best sprayed onto cropland to avoid the accumulation of pesticide-contaminated rinsate.

Thoroughly rinse the inside surfaces of the tank, paying particular attention to the surfaces around the tank fill access, baffles and tank plumbing fixtures. The use of a 360-degree nozzle will improve the thorough cleaning of tops and sides of the tanks. At the very least, I've learned a pressure washer with a straight handle and a straight tip just won't cut it. Don't attempt this - as if it were even possible - but short of crawling inside the tank to clean it, you are going to miss some hard to reach areas. The right tools for the job make the job so much easier and so much safer. Make sure you wear the proper personal protective equipment especially when cleaning the tank where splash-back is certain to occur.

Pressure sprayers are useful for removing caked on internal and external residues. Hot water can increase penetration of dried residues, but the addition of hot water rinsing may cause unacceptable health hazards due to the vapors produced. Carefully review label safety precautions for the agrichemicals and cleaning products used. See MU publication G1917, Personal Protective Equipment for Working with Pesticides.

Fill the tank with fresh water and add one of the following cleaning solutions or a commercially available tank cleaner and agitate the solution for 15 minutes. Add one of the following to each 50 gallons of water to make a cleaning solution: two quarts of household ammonia or four pounds of trisodium phosphate detergent.

Operate the spray booms long enough to ensure that all nozzles and boom lines are filled with the cleaning solution. Let the solution stand in the system for several hours or overnight. Agitate and spray the solution onto an area suitable for the rinsate solution.

Add more water and rinse the system again by using a combination of agitation and spraying. Remove nozzles, screens and strainers, and clean separately in a bucket of cleaning agent and water. Finally, rinse and flush the system once again with clean water.

Storing

After thorough cleaning, finish the needed maintenance, perform a calibration, and then remove nozzles and pumps and allow all parts of the sprayer to dry thoroughly. Seal all openings with tape or rubber stoppers to prevent insects, rodents and pests from nesting in the equipment. Then store the sprayer in a clean and dry location, especially when it will sit through the freezing weather of winter months.

For a complete guide to cleaning field sprayers refer to publication MU publication G4852 available online at http://extension.missouri.edu/explore/agguides/crops/g04852.htm.

Bill Casady
573-882-4370
CasadyW@missouri.edu