Deep in the potato country which runs all the way from Orkney to East Lothian, Elmwood has found a niche educational market. Roguing - the identification and elimination of plants not true to type - harks back to the turn of the century when merchants would pay premium prices for certified seed. Improvements in the 1940s brought compulsory grading and certification schemes and a bonus to the roguers.

Last year 14,327 hectares of land was laid out to seed potato, and each of the 60,000 plants per hectare was checked by roguing teams before the arrival of inspectors from the Scottish Office. At least 40 of last year’s roguers learnt their trade at Elmwood.

For two weeks at the end of June, a mixed bag of school-leavers, farm staff, students and teachers walked the college potato plots intent on identifying 40 different varieties of potato. From the shape and colour of stems, leaves and flowers, and the height of plants, students were required to identify at least 35 varieties to pass the course.

Rooting out rogues is only part of the job. While modern farming techniques have dramatically reduced the existence of rogue plants, viruses still threaten yields. Any plants that are diseased have to be removed before temperatures warm up enough to allow aphids to spread the infection.

All this sounds impossible to a horticultural illiterate, but Dave Hulbert, the course lecturer, insists there is much to gain from sticking at it. “Very few people fail and most normally gain full employment,” Mr Hulbert said. “The season normally lasts for about four weeks when the plants are in flower, anywhere from late June to August, which makes it an ideal and lucrative summer job for teachers.”

Although he accepts that the work is “tedious, dirty and physically demanding” and can involve long hours, the “social aspect and camaraderie of team work is really good fun”.

Elmwood College will begin its next potato roguing course in the last two weeks of June. Information is available from Dave Hulbert on 01334 658800.