Field Selection, Isolation and Roguing
Field Selection, Isolation and Roguing
This domain tests whether a candidate can choose a safe seed-production site, apply the correct isolation distance and remove contaminants at the right time. Questions often combine field history, volunteer plants, pollen flow and inspection timing.
Field selection rules
- Use land free from volunteer plants of the same crop and from noxious weeds.
- Check the previous crop and field history; a field that grew the same variety last season can contaminate the new crop.
- Ensure reliable irrigation, drainage and access; avoid fields with heavy weed pressure or difficult boundaries.
- Measure isolation from the nearest contaminating plant, not from the field edge or road.
- Use border rows, barriers or spatial separation where the prescribed distance is not available.
Rogue off-types, diseased plants and other crop plants before pollen shed; remove them from the field and destroy them. Late roguing after flowering cannot prevent pollen contamination.
Worked example
A foundation seed field of a cross-pollinated crop requires 400 m isolation. The nearest field of another variety is 340 m away. The actual separation is 340 m, so the field fails the isolation requirement unless the certification agency permits a specific border-row relaxation for that crop. A road or canal is not automatically an absolute barrier.
Traps that cost marks
Measuring from the field edge rather than the nearest plant; roguing after pollen shed; confusing diseased plants with genetic off-types; ignoring volunteer plants; and assuming a barrier is automatically acceptable.