Mustard field inspection at flowering
A seed certification agency inspector visits a 2.0 ha mustard seed crop (variety 'Pusa Bold', certified class) at 50% flowering. The crop was sown on 18 October with 4 kg/ha of foundation seed. The inspector counts 30 off-type plants with yellow flowers and late flowering in five 10 m² quadrats, while the total plant count is about 55 plants/m². The field's north side is 180 m from a farmer's field of 'Varuna' mustard; the south side is 90 m from a patch of wild mustard/rapeseed. The inspector also finds 4 plants of a different Brassica species and some aphid infestation. The seed grower argues that mustard is cross-pollinated but the distance is 'more than enough' and that roguing will remove all off-types. The inspector must decide whether to recommend rejection, provisional acceptance, or a re-inspection.
1. Calculate the off-type percentage and decide whether roguing alone can save the field.
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Off-type percentage: the inspector sampled 5 × 10 m² = 50 m². At 55 plants/m², that is about 2,750 plants. 30 off-types ÷ 2,750 × 100 = 1.09%. That is above the usual certified mustard limit for off-types (often 0.5% or lower), so the field cannot pass as it stands.
Roguing can reduce the count, but it must be done immediately and repeated. The off-types are late-flowering and yellow-flowered; some may already have shed pollen, and mustard is insect-pollinated. A single roguing pass followed by a re-count could allow provisional acceptance only if the count falls well below the limit and no off-types remain within the isolation zone. Roguing cannot fix a pollen cloud that has already moved.
2. Analyse the isolation distances and the significance of the wild Brassica plants.
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Isolation is the harder problem. The Varuna field at 180 m may or may not satisfy the same-species isolation rule for certified mustard; check the prescribed distance. But the south side is only 90 m from wild mustard/rapeseed. Wild Brassica is cross-compatible and is a serious contaminant; the required separation from wild relatives is usually larger than for a named variety. Four different Brassica plants inside the field confirm that the weed pressure is real.
The aphid infestation is a management issue-it can transmit viruses and weaken plants-but it is not by itself a reason to reject. The wild Brassica at 90 m is a reason to reject unless the source can be destroyed and the isolation re-established before flowering.
3. Recommend the inspection decision and state the conditions under which a re-inspection, if any, would be justified.
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Recommend rejection for certification, not provisional acceptance. The off-type level can be corrected by roguing, but the wild mustard/rapeseed at 90 m cannot be corrected by roguing the seed field. Destroying a border of the seed crop does not stop insect-borne pollen from the wild patch. A re-inspection would only make sense if the neighbour's wild Brassica were removed and the prescribed isolation distance were restored-unlikely within the flowering window.
The grower can still harvest the crop, but it should be sold as grain or, at best, as truthfully labelled seed after testing and with a clear declaration; it should not carry a certification tag. Record the rejection and the reasons so the case is defensible.