PHI and REI Compliance in the Vineyard

By VitiScribe Editorial·August 28, 2025·Updated November 18, 2025

Pre-harvest interval and restricted entry interval are printed on every pesticide label and enforced under federal law, but they're commonly confused with each other and occasionally ignored under harvest pressure. Understanding the difference, knowing what the record-keeping requirements actually are, and having a system to track both without errors are practical requirements for any commercial vineyard operation.

What PHI Means

The pre-harvest interval is the minimum number of days that must pass between the last application of a pesticide and harvest of the treated crop. The EPA sets PHIs based on residue studies demonstrating that after the stated interval, pesticide residue levels will be at or below the established tolerance for that crop commodity.

For wine grapes, PHIs in common programs range from 0 days for sulfur and most copper-based fungicides to 7 days for many synthetic fungicides including myclobutanil and tebuconazole, to 14 to 30 days for some systemic materials, to 60 days or more for certain organophosphate insecticides. PHIs are specific to the crop, the application site, and the label. The same active ingredient may have different PHIs for wine grapes versus table grapes or other crops.

Violating a PHI is a federal violation under FIFRA. The consequences are real: potential recall of wine made from the fruit if winery testing identifies above-tolerance residues, loss of winery contracts (many contracts include testing clauses that void payment for non-compliant fruit), and potential EPA enforcement action. Export markets, particularly in the European Union and Japan, have their own tolerance standards that are sometimes lower than US standards, creating risk for vineyards in international supply chains.

What REI Means

The restricted entry interval is the length of time, measured from the end of application, during which workers must not enter the treated area without wearing specific personal protective equipment. REIs are set by the EPA based on toxicity data for the active ingredient and are printed on every product label.

REIs range from 4 hours for many low-toxicity materials to 12 hours for common fungicides applied under the Worker Protection Standard to 24, 48, or 72 hours for more hazardous materials. Some organophosphate and carbamate insecticides carry REIs of 48 to 72 hours. During the REI, no worker may enter the treated area for any reason other than emergency rescue, medical treatment, or applicator equipment retrieval, unless wearing the specific PPE listed on the label for early entry.

The REI begins when the application ends and the treated area is no longer occupied by the applicator. It is measured in elapsed time from that endpoint, not from the beginning of the application.

The Critical Difference Between PHI and REI

PHI and REI operate independently. A product with a 0-day PHI and a 24-hour REI can legally be harvested the day after application, but workers cannot enter to pick without full early-entry PPE until 24 hours have passed. A product with a 21-day PHI and a 4-hour REI permits worker re-entry after 4 hours but does not permit harvest for 21 days.

Harvest operations involve workers entering treated fields to pick fruit. This means both the PHI and the REI must be satisfied before picking crews can enter a block. The more restrictive of the two governs when normal harvest activity is legally permitted. This is where compliance errors most commonly occur: a grower verifies PHI clearance without checking REI for an application made the previous day.

Record-Keeping Requirements Under WPS

The EPA Worker Protection Standard requires that for every WPS-covered pesticide application, the following records be maintained and available to workers and their representatives for two years: product name, EPA registration number, active ingredient(s), treated location, date of application, and REI duration.

This information must also be posted at a central location accessible to all workers. The posting must include the product name, active ingredient, treated location, and the date and time the REI expires. The posting must remain visible until the REI expires. After the REI, the posted information must be available in records for two years.

WPS also requires that agricultural workers who may contact pesticides in treated areas receive annual pesticide safety training and that the employer be able to document this training. Failure to document training is a WPS violation separate from and in addition to any record-keeping violations.

Common Violations in Vineyard Operations

The violations ODA, CAC, and EPA inspectors find most frequently in vineyard WPS audits fall into a few recurring categories.

Workers entering treated fields before REI expiration during irrigation, scouting, or leafing operations is the most common. This typically happens because the person supervising those operations was not informed about recent applications or did not have access to spray records. Distributing application information to foremen and supervisors on the day of application, not only to the spray operator, addresses this structurally.

Missing REI postings at field entry points is also common. The posting must be at every entry point to the treated area, not just at the spray shed. If a block has three road access points, each needs a posting during any active REI.

Harvest crews picking fruit before PHI clearance has been formally verified represents the highest-stakes violation because it involves potential residue exceedances in commercial product. Verification should be a written, documented step in harvest planning, not an assumption.

Using Software to Automate Interval Tracking

Manually tracking PHI and REI across dozens of blocks during the compressed pre-harvest period is genuinely error-prone. When multiple blocks are being sprayed and multiple blocks are approaching harvest simultaneously, the number of interval calculations that need to be correct at the same time creates real risk of error.

VitisScribe calculates PHI clearance dates and REI expiration times automatically from spray log entries. The harvest planning view shows the clearance status for every block, identifying any products with pending PHI intervals before crews are scheduled. This turns a calculation that could take an hour of manual work per week into a real-time status check that takes seconds.

For more on the record-keeping systems that support PHI and REI compliance, see our guides on vineyard spray record keeping and California DPR reporting.