Weed Control Guide for Ohio Field Crops

Weed Control Principles

Cleaning Spray Equipment

Clean sprayers immediately after use. Most herbicides, and especially growth regulator and ALS-inhibitor herbicides, will injure crops other than those for which they are labeled. Small quantities of these herbicides left in the sprayer from a previous application can cause extensive damage to the next field sprayed. The amount of these products left in the spray lines, filters, or tank can be sufficient to injure nonlabeled crops even when diluted by refilling the tank. Sprayer contamination can be more of a problem with plastic spray tanks, compared to stainless steel, since small amounts of some herbicides can adhere to the plastic. These herbicides can then be released from the tank walls when nitrogen fertilizer solution or solvent-based herbicides are used for subsequent applications.

Use of water alone is generally not sufficient to adequately clean spray tanks when switching from one crop to another, especially for growth regulator herbicides or some of the newer low-rate herbicides. Labels for these products generally recommend use of household ammonia or a commercial tank cleaner. Labels vary somewhat in their directions for sprayer cleanup, but the following is an example of a thorough sprayer cleanup procedure:

1. Drain tank and thoroughly hose down the interior surfaces of the tank. Flush tank, boom, and hoses with clean water for a minimum of 5 minutes.
2. Partially fill the tank with water and add houshold ammonia (one gallon per 100 gallons of water) or a commercial tank cleaner (follow label directions). Complete filling the tank with water, then flush the cleaning solution through the boom, hoses, and nozzles. Add water to completely fill the tank again, and allow to agitate or recirculate for at least 15 minutes. Again, flush the boom, hoses, and nozzles, and drain the tank.
3. Remove the nozzles and screen, and clean separately in a bucket containing water and the cleaning agent.
4. Repeat step 2.
5. Thoroughly rinse the tank with clean water for a minimum of 5 minutes, flushing water through the boom and hoses.

This procedure may need to be preceded by a pressure wash or steam cleaning of the tank to help remove caked deposits.

To prepare spray equipment for storage over the winter, disconnect all hoses and allow water to drain out. Coat bare metal parts with oil or a rust inhibitor. Disassemble metal nozzles and store in oil. Prepare the spray pump for storage based on the manufacturer's recommendations.

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