How do I read a crop-input label?
The label is the governing document in every jurisdiction. What the guaranteed analysis, derived-from, dilution rate, re-entry and pre-harvest fields actually tell you — and which ones are claims.
The short answer
The label is the governing document in every jurisdiction, and it outranks any website including this one. Read four fields first: what the active is, what rate applies to your crop, the re-entry interval, and the pre-harvest interval.
What each field actually tells you
The active ingredient, or actives, with concentration. This is what does the work, and it is the field to compare between products — trade names are not comparable and percentage totals do not tell you which component matters.
Guaranteed analysis, on a nutrient product, states the nutrient content the manufacturer guarantees, conventionally as N-P-K plus any declared micronutrients. Derived from names the materials those nutrients come from. Reading the two together is how you tell, for example, whether the potassium arrives as a sulfate or a chloride — which matters on chloride-sensitive crops.
Dilution rate and application method, per crop. A rate for one crop is not a rate for another. Re-entry interval is how long before a person may enter the treated area; pre-harvest interval is how long before harvest. They are different numbers and neither implies the other.
What is a claim and what is a fact
Composition fields are statements of fact the manufacturer is accountable for. Performance statements are claims, and their strength depends on what supports them and where they are registered.
"Approved for organic production" and a finished-product certification are different assertions resting on different evidence — the first can refer to the source of the materials, the second to an audit of the finished product. Registration status also differs by jurisdiction, so a product may be exempt or registered in one market and neither in another.
What to do when the label and a website disagree
Follow the label. This applies to rates, crops, intervals, protective equipment and permitted uses, and it applies to this site as much as any other. Nothing in this Knowledge section is a statement of approval in your country.
If a Vegalab page and a Vegalab label appear to contradict each other, tell us — that is a defect worth fixing, and it is the sort of inconsistency this library exists to eliminate.
When to get advice
Ask a Vegalab agronomist or your local extension service where a label does not cover your crop, where two products' actives may overlap, or where you are unsure which residue limit applies in your market.