Avoid herbicide spray tank contamination

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

Later planted and replanted crops have put us in the situation where postemergence herbicide applications will be made to several different crops during the same time period. Because of the vast number of acres that need to be sprayed with different types of products, caution needs to be taken to avoid spray tank contamination. In the past, it was particularly important to make sure the spray tank was clean when switching between corn and soybeans or other sensitive crops; however with herbicide-resistant crops, it is important now more than ever to not only make sure the spray equipment is clean when switching between crops, but when switching from herbicide-resistant crops, like Roundup Ready to conventional crops.

To avoid spray tank contamination, it is important to take the extra time and care to thoroughly clean out spray equipment: tank, lines, filters, sumps, pumps and nozzles. All of these areas can be a potential source of contamination. Even though the spray tank has been thoroughly rinsed, small amounts of herbicide residue can linger in the spray lines and filters. This can cause considerable damage to the next crop that is sprayed. For example, imagine spraying glyphosate on a Roundup Ready soybean field and then switching to spraying a postemergence corn herbicide on a conventional corn hybrid. How much damage do you think you would observe in the corn? I could imagine the first few hundred feet with dead corn plants, which could lead to substantial yield reductions at the end of the season. Or what if you sprayed dicamba postemergence on your corn and then switched to spraying soybeans or dry beans without properly cleaning out your sprayer. How many acres would you expect to see with cupped or twisted beans? Because these issues happen every year, it is important to thoroughly clean out your spray equipment when switching from one herbicide to the next. Below are a few tips to avoid spray tank contamination.

Always clean spray equipment thoroughly when switching from one crop to another or switching from an herbicide-resistant to a conventional crop hybrid or variety.

Just spraying until the sprayer is empty does not mean the sprayer is clean. There are herbicide residues that can be on the side of the spray tank in the spray lines, sump, pump, filters and nozzles. It is important to thoroughly clean all of these areas.

Clean spray equipment immediately or as soon as possible after spraying. Dried herbicide residues are more difficult to remove from the sprayer.

Always follow the herbicide label for directions and recommendations for the best method and cleaning agent to use when cleaning out the spray equipment. Several labels specify agents that work best at removing that particular herbicide’s residue from the spray equipment.

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