Principles of Potato Production
Varieties of potatoes
Potatoes are grown for 2 reasons:
1.Human consumption
2.Seed potatoes
There are 3 main types of potatoes
-First earlies
-Second earlies
-Maincrop
First Earlies
Harvested immature for immediate sale
Generally sown in late January or early February
(depending on the weather)
Harvested in May
Early harvesting may result in lower yield but
the grower is compensated by the higher
market value of the crop
First Earlies
The Home Guard is considered one of the most
superior of the first earlies in terms of eating
quality
Home Guard:
oval in shape
light skin
shallow eyes
creamy white flesh
Second Earlies
Can be harvested immature and sold
or
May be harvested at maturity and stored
If harvested immature:
Sown in mid-February/early March
Harvested in mid-June
Superior variety:
British Queen: Oval in shape
Floury white flesh
Main Crop
Sown in mid-March to late April
When soil conditions are suitable (7C)
Harvested in September/October
Because they are harvested at maturity the yield is
higher
Main crop varieties: Roosters, Kerrs Pinks, Records
and Golden Wonders
Main Crop Varieties
Records
Golden Wonders
Kerrs Pinks
Soil Suitability
• Deep, well-drained, sandy loam soils
• pH 5-6
• Stone free
• Light, sandy soils (Brown earths or grey brown
podzolics)
• South facing slopes for the first earlies
Climate
• Must be sown when plants will not be killed by frost
• Only coastal areas are suitable for growing earlies (no
risk of frost).
• Irelands Climate of mild showery weather is ideal for
potato growth.
• Drought at tuber development reduces yield
(irrigation could be used)
Rotation
• If grown too often in the same filed potatoes may be
affected by potato cyst nematode (eelworm)
Eelworm:
Soil borne nematode
microscopic
Affects root system
-Can be controlled by crop rotation
-Nematicides can be sprayed onto crop
-Some varieties are eelworm resistant
-Seed potato is only accepted from fields that are
eelworm free
Eelworm
Eelworm
Potato affected
with eelworm
Rotation
• Potatoes should not be sown for more than
one year in four in a field
• Potatoes grow well at any point in a rotation
• Farmyard manure (FYM) can increase organic
matter levels in the soil, a benefit for all crops
Seedbed Preparation
• Autumn plough to a depth of 22cm
• A fine seedbed is required
• Ridges should be high and wide
Varieties
• 40 – 50 varieties appear on the ‘National Catalogue of
Agriculture Plant Varieties’
• Potato varieties do not change as quickly as cereal
varieties.
Some common potato varieties:
Home Guard
First Early
British Queen
Second Early
Kerr Pink’s
Records
Maincrop
Golden Wonders
Cultivation
• Deep cultivation required
• Should be autumn ploughed to a depth of
22cm at least
• Cultivation in spring to give fine seed bed
• Rotavator or power harrow are used to give a
deep non-compacted seed bed
Rotavator: used to break up the land in
preparation for sowing for e.g. potatoes
Cultivation
• Stones can also be removed. This prevents brusing /
contamination when harvesting
• Machine deposits stones in a heap at the side of
machine.
• Ridging is done so stones are in furrows between two
ridges.
• Potatoes are grown on ridges. The ridging is either
the final cultivation operation or is done during
sowing
Potato Cultivators
Grading of seed
• Seed potatoes are graded into 2 sizes
35 – 45mm
before planting
45 – 55mm
35 – 45mm seeds are spaced at 20 – 25cm apart
giving about 60,000 seeds/ha
45 -55mm seeds are spaced at 30 – 35cm apart
giving about 40,000 seeds/ha
Sowing the Seeds
• Sown 10cm below the surface of the ridge
• Ridges should be 76cm apart
• Potatoes may be stored prior to planting
Sowing the Seed
• As the size of the seed increases, the number
of ‘eyes’ increases.
• Each eye grows into an individual plant
• Potato seeds can be sprouted prior to planting
by placing in shallow boxes and placing them
in greenhouses or well lit sheds
Sowing the Seed
• This is important for earlies, as it speeds up
growth, plant emergence and increases yield
• Commercially seeds are sown using an
automatic or semi-automatic planter
• Planting by hand can be done in small areas
• Certified seeds are not used annually – too
expensive
Sowing potatoes
Potato with ‘eyes’
Planting potatoes by hand
Producing home grown seed
• An isolated area is sown with certified seed
• It is sprayed with pesticides to control aphids
(e.g. greenfly which spread disease)
• The plants are killed off early to ensure
maximum number of potatoes in seed size
range (35 – 55mm in diameter)
• Methods of killing off potato: Burn off
Harvest
Herbicide
Fertiliser Requirements
Carry out a soil test
Usual rates of 10-10 20 applied are:
- Nitrogen: 125-150 kg/ha
-Phosphorous: 125-150 kg/ha
-Potassium: 250-300 kg/ha
Application is usually decided on after soil tests
Fertiliser is broadcast onto the soil before
planting
Fertilisers
• Too much nitrogen leads to high yields which
have poor eating quality
• Higher water content leads to poorer quality
Fertilisers
Experiment to estimate eating quality of potato:
• Cut potato into cubes
• Find mass of potato cubes
• Place in an oven at 100°
• Find mass after heating for 30 mins
• Repeat steps 3+4 until cubes have constant mass
• Calculate the loss in mass of potato cubes
Fertilisers
Results:
50g
200g
100
1 = 25%
(75%)
Potato content
Water content
Fertiliser
Low dry matter in potatoes
Too much nitrogen
Not enough potassium
Lack of sunshine
Weed control
• Weeds are controlled indirectly by crop
rotation and stubble cleaning
• Deep ploughing buries weeds
• Weed need to be controlled until potato stalks
and leaves meet across drills
• After this, the haulms meet and prevent
sunlight reaching the weeds (shading)
Weed Control
• Crops should be sprayed when 15-20% of
potato plants are visible above soil
• Spray should be a mixture of total herbicide
and residual herbicide of medium resistance.
• The total herbicide kills the potato tips but
they recover and continue growing
• In small areas hand weeding could be done
• Earthing up
Residual Herbicide: A herbicide placed on the target
are that remains active in the soil for a period of time
Earthing up
• Carried out when crop is 20 - 25cm high
Ridges become flattened out due to rainfall,
gravity etc
Potatoes may not be covered with soil
Therefore the earth is placed up around plant
Objective: to protect the crop from light
• Light exposure causes greening of tubers and
leads to alkaloids (poisonous) forming skins
• It is illegal to sell greened tuber – so they must
be discarded
Harvesting
• Earlies are harvested from early June onwards
• Early crops (new potatoes) have low yield but
get high price.
• Maincrop are harvested in late September or
October at full maturity.
• Haulms are killed off 3 weeks before
harvesting. Use contact herbicide.
• In these 3 weeks skin on tuber hardens leads
to less bruising and scratching on harvesting
Harvesting
• Most common potato
digger – elevator digger
• Wide, flat share running
through ridge under the
potatoes
• The soil and potatoes are
moved onto the elevator
where the soil drops
through the bars and
deposits the potatoes on
top of the soil. These are
then hand picked
Elevator Digger
Harvesting
• Complete potato harvesters can also store the
potatoes in a bin or alternatively the potatoes
may be transferred to a trailer with a side arm
Experiment to estimate the yield per hectare of
a root crop
1. Name the crop being estimated
2. Mark out an area of 1m2
3. Dig the crop out of the ground (remove crop) in the marked area.
4. Remove tops off the crop if necessary e.g. sugar beet.
5. Find the mass of the crop dug out
6. Record the mass
7. Repeat the process in a different part of the field
8. Find the average mass per square metre
9. Find the area of the field
10. Calculate the yield per hectare
11. Work out the total yield of the area to be harvested.
1 hectare = 10,000 m2
1 tonne = 1000kg
Yields
• Maincrop (average) 30 -40 tonne /ha
• First earlies, yield can be as low as 7 – 10
tonne / ha
Disease Control
Blackleg
Bacterial disease
Treatment: Avoid badly drained fields and storing
wet tubers
Gangrene:
Fungal disease
Treatment: Spray the crop with systemic fungicide
Storage
Buildings for storage should be:
• Leak proof
• Frost proof
discourage rotting
• Well ventilated- Less risk of sprouting and rotting
• Forced draught ventilation systems are needed where
stacks exceed 1.8m in height
• Easy access for tractors and trailers
• Strong, reinforced walls
Potatoes to be sold after February 1st should be treated
with sprout inhibitor or else refrigerated
Disease and Pest control
• Most common potato disease –
blight
Caused by: fungus Phytophthora
infestans
Symptoms: yellow (later black)
blotches to develop in the leaves
Premature death
Conditions: Warm, humid weather
Warnings are given by Met Eireann
Disease Control
Common Scab
Occurs if potatoes are sown in soils with high pH
Do not apply lime to the potato crop or the
previous crop
Fungal disease
Spray with systemic fungicide
Disease Control
Blackleg
Caused by: bacterium
Symptoms:Blackening of lower parts of stem
Blackening of stored tuber
Control: Use certified seeds
Avoid poorly drained fields
Avoid putting wet tubers in stores
Blackleg in potatoes
Disease Control
Gangrene
Caused by: Soil borne fungus
Symptoms: Dark coloured depressions on stored
tubers
Secondary infection by bacteria
Control: Use certified seeds
Avoid damage by harvest
Appply chemicals if necessary
Disease Control
Leaf roll
Viral disease
Spread by aphids
Treatment: spray with insecticide
Leaf mosaics
Viral disease
Spread by aphids
Treatment: spray with insecticide
Pest Control
Wireworm: use poison baits
Slugs: use slug pellets
Aphids: use insecticides or ladybirds
Potato cyst nematode: Employ crop rotation
Potato cyst nematode
Yield
First Earlies: 7-10 tonnes/ha
Main crop: 30-40 tonnes/ha
Storage
• Well-ventilated
• Frost and leak proof
• Easy access for tractors and trailers