Volunteer Potatoes

  • Potatoes are often seen growing as casuals on tips and waste ground but it is the volunteer potatoes found in vegetable gardens and arable fields that are the weed problem.

  • These arise from seeds, tubers and tuber pieces that remain in the soil following an earlier potato crop.

  • After potato harvest there may be as many tubers left in the soil as were planted originally.

  • Volunteers that grow from missed or ground-keeper tubers develop vigorously and are difficult to eliminate in poorly competitive crops like leeks and onions, particularly from within the crop row.

  • Where a berry producing potato cultivar such as Maris Piper has been grown, volunteer potatoes that develop from the seeds can be a problem

  • The foliage and green tubers of potatoes are poisonous to livestock.

  • Potato berries and stem pieces can contaminate pea and green bean crops harvested for processing.

  • Volunteer potatoes act as an attraction to pests and diseases, as they carry any diseases suffered during the previous year.

  • All potato cultivars flower but many produce flowers that drop off soon after pollination.

  • Some cultivars, however, form berries each containing 200-300 seeds.

  • Potato berries are produced in large quantities by the cultivars Vanessa, Cara, Desiree, Pentland Ivory, Maris Piper, Maris Peer and several others.

  • Potato seedlings emerge from May to late-June and may continue to appear until September.

  • Plants from seedlings that emerge up until June may produce small tubers that remain in the soil as ground-keepers over winter.

  • Potato foliage is killed by temperatures of around 2F.

  • Once shed, potato seeds can remain viable in soil for 3-9 years.

  • The seeds will also remain viable for long periods in dry-storage at low temperatures.

  • After potato crop harvest, over ten times more tubers can survive following ploughing compared with shallower cultivations.

  • Cultivation with tines is more likely to leave tubers near the soil surface where they can be killed by exposure to frost.

  • However, this may not be effective in a mild winter and even a moderately hard winter is unlikely to eradicate the entire volunteer population.

  • The tubers need prolonged exposure at freezing point to destroy their cell structures.