This is essential to prevent serious damage to a crop. Disasters happen — and they may be occurring more often than we think.
A water rinse is not usually enough to remove herbicide residue from the sprayer system. Herbicides can bind to the tanks and hoses, and most need water plus a cleaning solution to remove them. If not, you never know when the bound herbicide molecules will be released. Some surfactants do a very good job of scrubbing a week’s worth of herbicide residue from the sprayer system, creating an unexpected and damaging tank mix. Talk to your retailer about effective tank cleaners.
End the day with an empty tank. A University of Missouri factsheet recommends that sprayer operators end the workday with an empty tank. It says: If you will be using the same agrichemical the next day, thoroughly flushing the sprayer tank and sprayer with clean water is sufficient and will help prevent drying and hardening of pesticide residues. If a different agrichemical will be used, then a more comprehensive procedure is recommended immediately after use.