Restrictions are put on pesticide labels to make sure crops are safe to eat and that future crops will not be affected by pesticide residues. Common types of label restrictions include harvesting restrictions, slaughtering restrictions, grazing restrictions, and replanting restrictions.
Harvesting restrictions indicate when a crop can be harvested after a pesticide application. Research determines how long it takes for a pesticide to break down to below the maximum residue limit. This period is called the pre-harvest interval (PHI) or days-before-harvest. The PHI may vary with the crop type, the rate applied, and whether the application is outdoors or in a greenhouse. Refer to the pesticide label for the pre-harvest interval for each crop-pest combination. Do not harvest the crop before the pre-harvest interval has elapsed.
Slaughtering restrictions state when an animal can be slaughtered after a pesticide application. For example a label may say "Leave a seven day interval between last spray and slaughter". This time period (pre-slaughter interval) allows a pesticide to break down to below the maximum residue limit in the animal. Pesticide labels state the required pre-slaughter interval, which may vary for different rates and for different species of livestock. Refer to the pesticide label for the appropriate pre-slaughter interval for the type of livestock you are treating.
Milking restrictions state when or if a dairy cow can be milked after it has been treated with a pesticide. For example, "Do not apply within 30 days of freshening" or "Do not apply before milking". Since pesticides applied to dairy cows can move into milk, pesticide labels may have milking restrictions to make sure milk does not contain pesticide residues. The interval on a pesticide label applies to the pesticide rate and type of animal stated on the label. Check and follow pesticide labels to make sure milk does not have pesticide residues above the maximum residue limit.
Grazing restrictions are designed to protect animals and to ensure pesticide residues will not exceed the maximum residue limits in milk or meat products. Grazing restrictions state when animals are allowed to graze an area treated with pesticides. For example, a label may say: "Allow 3 to 5 days for the herbicide to translocate into all plant parts before grazing." Other labels may prohibit grazing treated crops. For example, a label may say: "Do not graze the treated crops or cut for hay". Check pesticide labels before applying the pesticide to make sure the timing is compatible with your grazing plans.
Replanting restrictions state when, and what crop can be planted on land that has had a certain pesticide used on it. The replanting restrictions protect future crops from phytotoxic effects caused by pesticide residues in soil and also protect consumers by helping ensure future crops will not contain pesticide resides above the maximum reside limits. An example of a replanting restriction is: "Rotation of fields treated with this insecticide to wheat is acceptable after a minimum plant-back interval of 30 days and to beans after a minimum of 9 months. Rotation to all other food and feed crops require a 12 month plant back interval." Other times the label may list the crops that can be grown safely the following year.
Replanting restrictions are typically only found on a few labels. They can be found under several different topics including: following crops, rotational crop restrictions or replanting, or re-cropping.