Grower guides

Withholding periods and re-entry intervals, explained

Two clocks start the moment you spray a block. One protects the fruit, one protects your people, and mixing them up is one of the more expensive mistakes a vineyard can make.

The withholding period protects the fruit

A withholding period (WHP) is the minimum number of days that must pass between applying a product and harvesting the crop, so residues have time to fall to a safe level. It comes off the product label, and the label is the legal source. Harvest inside the withholding period and the fruit can breach residue limits — the winery's residue testing will find it, and a load can be rejected on the spot.

The re-entry interval protects your people

A re-entry interval is a different clock: how long workers must stay out of a treated block after spraying, unless the label allows earlier entry with specified protective equipment. It has nothing to do with the fruit. A block can be weeks clear of its withholding period and still unsafe to send a crew into after a fresh spray, and the reverse is just as true.

How the clocks combine in practice

• The longest product wins. A tank mix carries the withholding period of its longest product. One short-WHP fungicide doesn't clear a block that also got a long-WHP one in the same pass.
• Every block keeps its own clock. The withholding date belongs to each block the spray covered, not to the spray. Two blocks sprayed a week apart clear a week apart.
• Respraying resets the clock if the new product's withholding reaches further out than the date the block already had.
• Know the earliest harvest date before booking a pick. The question isn't "when did we spray" but "when is this block clear" — that's the number to check before harvesters and cartage are locked in.

Wine grapes: the label is only half the story

Label withholding periods are set for domestic use. Because most Australian wine is exported, the industry works to the AWRI's agrochemical recommendations — the "Dog Book" — which for many products recommend longer restrictions on use before harvest so the wine clears export residue limits. Wineries commonly write those recommendations into grower contracts, so the practical withholding on a wine-grape block is often the stricter of the two. Check what your winery holds you to.

Where growers get caught

Almost every withholding breach traces back to the same thing: the harvest decision was made from memory rather than from the record. A late-season botrytis spray with a long withholding period, a pick brought forward by weather, and a block that "should be right by now" — that's the pattern. The fix is boring: a spray diary that turns every spray into a per-block earliest-harvest date, checked before every pick.