Potatoes
Potatoes are a popular, high yielding root crop of the Solanaceae Family. First
cultivated in Ireland in the early 17th century, they remain a staple part of the Irish
diet today.
Part of their popularity is…
1. High yield - ware crops yield up to 40tonnes/ha
2. Grow in virtually all soils and pHs
In modern times, potatoes are eaten as is, or as chips/fries; sold by local fish & chip
shops or large, multinational corporations such as McDonald's or Supermacs.
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To supply potatoes year round, potatoes are harvested at 3 times throughout the
year.
1. First Earlies: Harvested in May
2. Second Earlies: Harvested in July
3. Maincrop or Ware: Harvested in October
The only disadvantage to this is reduced yields for first and second earlies.
Varieties
Potato crops are sown based on the traits of their variety. Some traits include
Yield: high yields are profitable and desired.
Eating Quality: crop should be high in DM and desired by consumers.
Resistance to disease: to reduce loss of crop/maintain as high of yield as possible,
the crop must be resistant to disease e.g blight, leaf mosaic
Some examples of potato varieties include
· Rooster: main-crop potato. Moderately high yielding, red skinned and yellow
fleshed. Good tuber blight resistance. It has good resistance to common scab
and leaf roll virus. It is classed a medium dry potato and is used mainly for
boiling and baking.
· Queen: second early potato. Have gained popularity in Ireland in recent
years. The variety has white skin and flesh, an excellent floury texture,
beautiful taste and can be used for boiling, steaming, roasting and chipping
· Kerr’s Pink: another main-crop variety. Red skinned, white flesh, high DM
and suitable for boiling, chipping and baking. Susceptible to common scab
and tuber blight. It has the disadvantage of being difficult to store.
Sowing
Crop should be sown in April/May, depending on weather conditions i.e. there should
be no risk of frost – frost will kill the seed.
Conditions must be dry at sowing, as well as at harvest.
Crop rotation is incredibly important for potato farming. Crop can only be sown 1 in 4
years. This is to prevent a build-up of pests in the soil and to prevent nutrients in the
soil being overused.
Soil must be ploughed to 25cm, however this should be varied during crop rotation to
prevent a plough pan developing.
All stones must be removed from the soil to prevent damage to the crop.
Seedbed should be ploughed and harrowed the day before sowing. However, the
seedbed must not become wet.
Fertiliser is broadcast on the harrowed seedbed. A 7-6-17 NPK fertiliser is used.
Nitrogen: used to increase yield. Too much can cause large tubers DM to be
lowered.
Phosphorus: Increases DM, hardens skins, reduces chance of tuber blight.
Potassium: Increase tuber size. However, excessive K will lead to reduced DM,
therefore a potash e.g KCL is used.
Potatoes are sown using a potato planter.
Potatoes are sown in drills. Drills are trenches in the soil, called a furrow, with raised ridges
on either side. Potatoes are sown in these ridges. Ridges are 75cm wide, potatoes are 15cm
from the surface of the soil and potatoes are sown every 30cm.
Crop Protection
As with all crops, potatoes must be protected from weeds, pests and diseases. This is
ensued yields are high and the crop remains undamaged.
Weeds
Weeds affect all crops, as the two species compete for water, sunlight and soil nutrients.
Weeds are dealt with in the following manners
1. Ground is ploughed on January 15th. This is to encourage weeds to grow and
establish. The seedbed is then ploughed again before sowing, ploughing in weeds,
killing them.
2. Harrowing will kill any weeds that still remain or if ground is not ploughed twice.
3. Crop rotation, as with all crops, helps to prevent weeds.
4. Post Emergent Spraying: This is a control method unique to potato plants. As each
plant produces 4-5 stems, the plant has 4-5 chances to grow. The crop is sprayed
with a contact herbicide when ¼ of the crop haulms emerge. This kills all weeds and
the crops haums, however the crops other stems mean the crop continues to grow.
5. Shading is a common defence against weeds for root crops. Haulms will shade the
ground beneath them, prevent weeds from photosynthesising.
Pests
As with all crops, there are common pests associated with potato crops. Most are dealt with
using crop rotation, however some are dealt with by unique methods.
1. Wireworms, which eat the roots of the developing crop are combated with crop
rotation.
2. Slugs must be controlled and, if possible, not present on the farm. These are killed by
slug pellets spread on the sown fields.
3. Crows are eradicated by a scarecrow, bangers or the most permanent option hunting them.
4. Rats are controlled with poison, cats or ensuring all entries to the farm and storage
are as sealed as possible.
5. Aphids: a vector for viral diseases, they are a pest associated with cereal crops also.
Aphidicide may be sprayed on the crop, killing aphids after contact with the plant,
reducing crop loss.
Organic methods involve introducing a natural predator of aphids on the farm i.e.
ladybirds or cutting back hedges to prevent housing in winter.
Another method is to grow potatoes, specifically seed potatoes in coastal counties, such as
Donegal. The cool, windy climate is unsuitable for aphids and therefore are not a problem on
coastal county farms.
Disease
1. Leaf Roll - Virus
2. Blackleg - Bacteria??
3. Blight - Fungal