1. Crop Production
Potatoes

2. Potatoes Potatoes are the most widely used vegetable in Ireland
Potatoes are grown by farmers for two reasons:
“Ware potatoes” to be eaten by humans and exported as food
“Seed potatoes” to re-plant and grow new potatoes
80% of commercial potato production is concentrated in Meath, Dublin, Donegal, Cork, Wexford and Louth

3. Potatoes facts Is a root crop Are underground stems called tubers
Belong to the family Solanaceae
Are perennial plants that grow to a height of approximately 60cm

4. Categories of Potatoes
Potato are classified as:
First earlies
Second earlies
Maincrop
First and second earlies are planted in February and are harvested immaturely from May onwards.
Maincrop are harvested when they are fully mature in September and October.

5. 1st Earlies
2nd Earlies

6. Roosters
Kerr Pinks

7. From early February onwards
Class
Variety
Soil Type
Sowing Date
Harvesting
Yield
Example
1st Earlies
Home Guard
Colleen
Epicure
Sandy
From early February onwards
From May onwards. Available commercially from May to June
12 – 18 tonnes/ hectare
Oval shape, light skin, creamy white flesh.
Suitable for boiling, roasting and chipping

8. 2nd Earlies
British Queen
Orla
Carlingford
Sandy
From mid February onwards
From July to September
17 – 25 tonnes/ hectare
British Queen.
Oval shape, floury white flesh. Suitable for boiling, roasting and chipping

9. Main Crop
Rooster
Record
Golden Wonder
Kerr Pinks
Loam
pH 5 – 5.5
From March onwards
From Aug to Oct. Available commercially from Sep to May
30 – 40 tonnes/ hectare
Irregular round shape with distinctive pink skin, deep eyes and white floury flesh
Superior in terms of eating and cooking quality

10. Seed Production
For commercial potato production, certified seed must be used
Certified seed potato production is centred around Donegal for two reasons:
Firstly, cool windy conditions in Donegal keep the aphid population low. Aphids are vectors (carriers) of a number of plant viruses.
Secondly, Donegal is isolated from other potato- growing regions in the country, therefore preventing the spread of diseases.
Certified seed is also produced by micropropagation.

11. New seed potatoes
New varieties of potatoes are being produced through Teagasc’s Potato Breeding programme in Co. Carlow
New varieties are produced form crossing genetically different parents and a trialling process takes place where their characteristics are tested.
Each variety is compared under a series of headings.
Tuber size
Percentage dry matter
Processing quality
Yield per hectare
Susceptibility to blight and other diseases
Resistance to eelworm, etc.

12. New seed potatoes Newly developed varieties include: Cara Orla Colleen
Camelot
Slaney
Cristina

13. Cultivation Practices
Soil suitability:
Earlies require sandy soil which contains more air and is easier to heat up.
Main crop require well drained loams which holds more moisture in the summer
Soil pH between 5.5 and 6.
Rotation:
Vital to prevent the build up of potato cyst nematode, a soil-borne pest of potatoes.
Potatoes should not be grown in the same field more than once every four years. For seed potatoes, once every five years.

14. Cultivation Practices
Preparation of seedbeds and sowing:
Potatoes need deep well cultivated soils.
Land is ploughed and tilled in preparation for planting.
Stones are removed
A ridger is used to form drills 80cm apart. Wider drills mean quicker harvesting
A potato planter drops the seed down into the soil at least 15cm below the surface to allow for good soil cover. This ensures the tuber is not exposed to sunlight as too much destroys the crop
The seeding rate is 2.5 tonnes/hectare
Seeds may be sprouted prior to planting.

15. Preparation of the Seedbed
A de-stoner
Drill formation

16. Sprouting
Potato seeds are exposed to light so that they develop shoots.
This gives the seeds a head start.
It is essential when growing earlies.
Sprouting speeds up growth and improves yield.

17. Fertiliser Application
Most growers apply a compound fertiliser such as 10:10:20.
Commercial growers place the fertiliser in a band either side of the potato drill, so as to promote uniform growth.
Excess nitrogen and excess phosphate depresses the dry matter content of potatoes, while the addition of sulfate of potash increases dry matter.

18. Important elements for potato growth
Nitrogen – helps with growth of plant
Phosphorous – gives a higher yield
Potassium – increases dry matter and improves skin
Magnesium – part of chlorophyll for photosynthesis

19. Weed Control and Earthing Up
Deep ploughing in the preparation of the seed bed can eliminate weeds.
A residual herbicide should be sprayed before the potato plant emerges. This helps to eliminate annual and soft weeds growing.
For perennial weeds, e.g. common cleavers, a contact herbicide is used. Contact herbicides destroy only the plant tissue in contact with the chemical
Scotch grass is killed off using a graminicide, e.g. glyphosphate.
Once the stems and leaves (haulms) of the potato plant grow, they form a canopy so emerging weeds have no sunlight for photosynthesis and growth.

20. Earthing up
Earthing up has not been practiced in commercial potato production for many years
Once potatoes are 20 – 25 cm in height, a ridger is used to widen ridges and deepen furrows so developing potatoes are not over-exposed to light and fungal spores in the air.
It also reduces the emergence of weeds by smothering them.
Sunlight can cause greening of the tuber where poisonous alkaloids, e.g. solanin, build up
Earthing up is also used as a preventative measure against blight. Spores from the leaf find it difficult to attack tubers as additional soil is packed around them
With advancement in technology, drills are wider than before so earthing up is not required. Fungicides and herbicides are also used.
Organic farmers may still practice earthing up as they don’t spray any chemicals.

21. Potato Diseases Potato blight
Blight is caused by an airborne fungus.
Warm humid weather favours the spread of blight.
Potato crops should be sprayed every ten days with a fungicide when blight warnings are issued by the Met Office.

22. Lifecycle of blight
Fungal spores can survive the winter in blighted tubers or in the soil
Hyphae emerge from these spores and grow between the cells in the leaf of the potato plant.
Haustoria (fine branches of hyphae) penetrate the cells of the leaf and absorb food from them.
Sporangiophores then develop and grow out through the stomata and produce more spores.
Zoospores, with flagellae, swim in a film of water on the leaf and produce a germ tube to penetrate leaf cells and form new hyphae.
Rain washes spores into the soil, infecting tubers or they may come in contact with spores at harvesting if infected haulms are not burned off.

23. Lifecycle continued
Blight affects the potato haulms by causing black spot on the upper side of the leaves, while grey mould develops on the bottom during wet conditions. Eventually the whole plant appears black and withered.
The tuber displays a brown/purple colour skin with shrunken areas. A rusty brown colour is evident when the potato is cut open

24. Blight

25. Prevention of Blight
Spray with blight fungicide every 7 to 9 days from May 1st for 1st Earlies, mid May for 2nd Earlies and June 1st for maincrop potatoes
This means that 18 to 20 applications of fungicide are made until the end of the growing season.
If blight does occur, spray with a curative fungicide, e.g. Curzate – M, twice, four days apart
A good rotation will reduce the likelihood of blight as spores will not be present in the soil
The use of certified seed ensures blighted seed is not used
Chemically burning haulms three weeks prior to harvesting prevents spores being washed onto soil

26. Potato Diseases Blackleg is a disease caused by bacteria.
Cool, wet weather favours the spread of blackleg.
It commonly affects the established crop.
The disease is spread through contaminated seed.

27. Pests
Wireworms can sometimes be a problem if potatoes are grown after pasture.
Slugs can damage tubers especially in wet summers.
Aphids are vectors of viral diseases.

28. Harvest Early varieties are harvested from May onwards.
Maincrop is harvested in September and October.
The haulms are killed off with a herbicide and the tubers are left for three weeks to allow the skins on the tubers to harden.
Potatoes are harvested using an elevator digger.

29. Storage
Potatoes must be stored in purpose-built buildings that are well ventilated, leak proof, insulated and frost proof.
Potatoes are often sprayed to prevent sprouting.
Commercial farmers store their potatoes in refrigerated units.

30. Yields First and second earlies yield around 7–10 tonnes per hectare.
Maincrop yield between 30 and 40 tonnes per hectare.