Pre-harvest interval (PHI) and re-entry interval (REI) explained

Two numbers on a plant protection product label decide when you may harvest a treated crop and when people may go back into a treated field. Getting them wrong can mean residues above the legal limit, rejected loads or a risk to workers’ health. Here is what they mean and how to keep track of them.

What is the pre-harvest interval (PHI)?

The pre-harvest interval is the minimum time that must pass between the last application of a product and the harvest of the treated crop. It is usually given in days, and it can differ between crops for the same product.

The PHI exists so that residues fall below the maximum residue level (MRL), the legal limit for that product in that food or feed. Harvesting earlier than the label allows can leave residues above the MRL even if you used the correct rate.

Things to keep in mind:

• The PHI counts from the last application, not the first.
• If you apply several products, the longest PHI among them decides the earliest harvest date.
• Some labels say “no PHI needed” or give the latest growth stage at which the product may be used instead of a number of days.
• Export markets may have different MRLs, so buyers sometimes ask for longer intervals than the label requires.

What is the re-entry interval (REI)?

The re-entry interval (also called the restricted-entry interval or re-entry period) is the time after an application during which people must not enter the treated area without appropriate personal protective equipment. It protects workers from contact with fresh residues on plants and soil.

In the United States, the Worker Protection Standard requires employers to observe the REI on the label and to inform workers about treated areas. In other countries, labels and national rules set similar conditions. As with the PHI, the REI depends on the product and is stated on the label.

Where to find PHI and REI

Both are set when a product is authorized and appear on the product label or in its safety and use instructions. Always use the label that applies in your country and for your crop: the same active substance can carry different conditions in different markets.

How records help you stay within them

You can only respect a PHI if you know exactly when the last treatment took place on a field. That is where dated records pay off:

• Record every application on the day, with the date and time, field, crop and product.
• Before harvest, check the last treatment on each field and compare it with the PHI on the label.
• Tell your team. If several people work on the farm, everyone needs to know which fields were just treated.
• Keep the records so you can show buyers when the crop was last treated.

In Agro Notes, every treatment is stored with its date, time, fields and product, and the field history shows the latest treatment at a glance. You can plan treatments ahead, mark them as done, mention the people who need to know and export the records to PDF or CSV for a buyer or an audit.