MRL compliance starts in the field, not in the lab report.

Why dried herbs fail more often than fresh produce

Pesticide limits in the EU are set by Regulation 396/2005, and where no specific limit exists, a default of 0.01 mg/kg applies — close to the limit of detection. Dried herbs carry an extra handicap: drying removes most of the water but not the residues, concentrating whatever was on the fresh leaf several-fold. A spray that would have been unremarkable on fresh mint can put a dried lot comfortably over the limit.

Add compounds that arrive from outside the field — chlorate from chlorinated wash water, residues drifting from a neighbour's cotton — and you see why testing alone is not a strategy. Testing tells you which lots to reject. It doesn't produce lots you can accept.

The controls that actually work

1. Contracted, named plots. If you don't know which field a lot came from, no other control is real. Plots should be mapped and contracted before the season starts, so every downstream record hangs on a named piece of land.
2. An approved-inputs list, agreed before sowing. The grower should know from day one which plant-protection products are acceptable for the destination market — and which ones end the contract.
3. Spray diaries, kept per plot and per application. Product, dose, date. Boring, and decisive: the diary is what turns a residue result from a mystery into a traceable event.
4. Pre-harvest interval (PHI) enforcement. Most MRL failures are not exotic chemistry — they are legal products sprayed too close to picking. Insist the PHI is enforced and recorded, not assumed.
5. A field-sample screen before purchase. Require that, before a plot's harvest is committed, a field sample goes to an ISO/IEC 17025 laboratory for a multi-residue screen — and that a field which fails is not bought. This is the single control that changes the economics: rejection happens at the farm gate, not at Rotterdam.

What a commercial lot should ship with

The commercial lot should then carry its own ISO/IEC 17025 report referencing EU Reg. 396/2005, tied back to the plots of origin along with the spray diary, PHI record and custody chain.

Three questions for any supplier

• Can you name the plots behind this lot — and show the spray diary?
• Was a residue screen done before you bought from the farmer, or only after?
• Which laboratory ran the panel, and is it ISO/IEC 17025-accredited?

A supplier with real field controls answers all three in one email, with documents attached rather than assurances.

To be plain about our own position: we do not yet buy from contracted plots — no crop has been purchased and no laboratory is yet appointed. The programme above is what we are designing, and we will name the growers and the laboratory when they exist.