Proper Pesticide Application/Use
It’s not uncommon for me to reference pesticides in news columns/consultations etc…. Whether a fungicide for wheat or corn diseases or insecticide for alfalfa weevil or a herbicide for weed/brush control, I often include a statement along the lines of: always read and follow label directions. It’s a generic statement that really deserves much greater explanation.
Every pesticide has a label. At its most basic, it outlines the product’s active ingredient, crops it can be used on, and pests it controls – but there’s more to them than that. Reentry intervals (REI) are an example. They are in place to prevent entry before it’s safe to come in contact with the applied product.
Pre-harvest intervals (PHI), pre-plant restrictions, and grazing restrictions are important, too. They’re in place to insure we don’t harvest while product residue might still be present and potentially cause problems for consumers or animals or markets. It also provides guidelines to make sure we aren’t trying to seed something back too soon following application.
Take the harvest restrictions on some of our common pasture/hay field herbicides (chart above) for example. Many of them have very few restrictions for grazing by beef or non-lactating animals, but quite a few have restrictions when it comes to grazing by lactating dairy animals. They have different restrictions for removal before slaughter as well. The restrictions before hay harvest are even greater, with many products requiring a minimum of a week or more between application and haying, That’s an important point this time of year when we might be trying to control weeds ahead of hay harvest.
The instructions and application rules on product labels are the law. Can’t find a label? Many companies have them available online and they are available from other sources (Greenbook, CDMS, etc…) as well. You can also get a quick look at some of the label requirements using our 2025 KSU Chemical Weed Control Guide (online or via any District Office). It provides a very brief snapshot of many labels plus application guidelines. Drop me a line if you are interested in a copy – and always read and follow label directions.