Corn leaf speckling from tank contamination
- Most tank contamination issues can be avoided by following good equipment cleanout practices.
- Try to always spray out the full load before finishing for the day and flush the boom with clean water.
- Switching from pre-emergence products to post-emergence products may result in crop injury if precautions are not taken to clean and flush out equipment properly.
- Proper cleanout of the spray tank, booms and lines are critical components to the application process and protection of the crop.
- When using a tank cleaning agent, remember to always read and follow the label and be patient, proper tank cleanout takes a significant amount of time.
MANAGING THE RISKS
Crop injury from sprayer tank contamination continues to be one of the most common crop protection application concerns in agriculture. Most tank contamination issues can be avoided with a minimal investment of time and effort. It is also important to recognize the circumstances that increase both the risk of tank contamination and the potential for crop response. This is extremely important, especially with multiple herbicide tolerant traits in various crops currently in the marketplace.
Switching Crops – This poses the highest risk for tank contamination problems and for crop response. Solution – As much as possible, dedicate sprayers to use on a specific crop. When you must use the same sprayer for different crops, be prepared for the necessary downtime involved in proper tank cleanout.
Changing to Post-Emergence Applications – Several soil-applied products may cause crop response such as spotting, speckling, burning, or distorted growth if residue is contaminating the spray tank. Solution – Recognize which products may cause adverse effects to crop foliage. Take the time for a thorough system flush or for a complete tank and system cleanout.
Highly Active or Persistent Products – Certain products are active at low concentrations, or are particularly prone to adhering to tanks, boom lines, end caps and nozzle bodies. Solution – Create a list of the products you handle, and which are likely to cause problems. Note when those products are being used. Take extra care when prior spray loads have included those products. With the persistent products, crop response may be noted even when multiple loads have been sprayed since those products were first used.
Accidental Tank Cleaners – Some products or tank mixes are surprisingly good at cleaning tanks and booms of residue from previous loads. Problems of this kind normally show up with post-emergence applications. Solution – A simple rinse or water flush ahead of these products and mixes may not be enough. Be prepared for a thorough tank and boom cleaning.
General Recommendations:
Frequent, Thorough Rinsing – There is no substitute for frequent rinsing of the sprayer system. This keeps residue from building up. As a minimum, sprayers should be thoroughly rinsed, and booms flushed before parking equipment at night or when equipment will be inactive.
Spray Out the Loads – Sprayer and boom contamination can be partially caused when product sits in the tank and booms for extended time periods, even overnight. Completely spray out the load, especially with the last load of the day. If you are interrupted by sudden rain or other problems, arrange to agitate the partial load frequently to avoid product settling and sticking to tanks and in booms.
Special Nozzles / Rinse Systems – If your sprayer is equipped with rinse and flush systems make use of this equipment. It is always best to spray out rinsate on the field where the application took place. If you don’t have this equipment, arrange for someone to bring rinse water to you and use special nozzles designed to help rinse insides of spray tanks.
Straighten Hoses – Hose bends and end caps are places where product can settle out in the spray boom. To the best of your ability, straighten these hoses and eliminate other “dead zones” where product can accumulate.
Chemical Inductors – Chemical Inductors are prone to product and product solution sitting in the bottom near the valve. This becomes an issue when switching from one crop to another without thorough cleanout. To best minimize: always clean with fresh water after all products are added into the tank and do a complete and thorough cleaning when doing a whole system cleanout, this will help to alleviate crop response due to contamination.
THE PROPER CLEANOUT PROCEDURE
Understanding the importance of proper sprayer tank clean-out procedures, and practicing these procedures, should be a critically important part of the application process. Remember that crop protection product labels frequently specify the proper sprayer cleaning process for these products. Become familiar with the label guidelines for sprayer cleaning. These general guidelines, offered below, should not take the place of label-specific cleanout recommendations.
There are two essential aspects for effective sprayer system cleanout - time and patience. Thorough sprayer cleaning is very time consuming, however, a crop response complaint can be costly in lost time investigating, company dollars and reputation. Remember that some herbicides can even cause crop response at the parts per billion (PPB) level.
When switching crops, and sometimes when switching from soil to foliar applications, it is essential to take the time for a thorough tank clean-out. (A complete tank clean-out will take approximately 12 to 24 hours.) Review the following general tank cleanout procedures. (A 1200-gallon tank is assumed for these guidelines.)
- A thorough clean-out involves three, separate, time-consuming rinses that require a total (minimum) of 900 gallons of water, or 300 gallons per rinse.
- The first rinse uses 300 gallons of clean water, only. Be sure to circulate the water thoroughly through the sprayer to ensure that the agitation reaches above the sparge lines.
- Recirculate the water through the entire sprayer system for a minimum of thirty minutes. One hour is preferred.
- Drain the entire tank, lines, and booms. Capture the rinsate to use as makeup water (for the same crop) or spray the rinsate on an appropriate field.
- Immediately, add another 300 gals of water, plus the labeled rate of tank cleaner. If you’re using FS RinseOut™, use six quarts of tank cleaner in the 300 gallons of water (2 qt./100 gal.).
- Thoroughly recirculate the water, containing the tank cleaner, for one hour. Be sure to charge the booms and then let everything sit for a minimum of four hours… Overnight is preferred.
- The next day, completely drain the entire sprayer. Remove and check all strainers and screens. (Note: On a 120-foot boom (15-inch spacings), that means 96 nozzle screens!)
- Be sure to clean the end caps from each section of the boom.
- Add the final 300 gals of clean water and recirculate for a minimum of 30 minutes. Again, a one-hour rinse is preferred.
- Drain the entire tank, lines, and booms.
- When getting ready to spray the first load, after cleaning the tank and sprayer system, find a place where you can safely run full spray for thirty to sixty seconds before making the crop application. This will clear most remaining contaminants from the boom.
Herbicide residue in boom end caps