Principles of Potato Production Varieties of potatoes Potatoes

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 • p. H 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 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 22 cm • 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 22 cm 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 – 45 mm before planting 45 – 55 mm 35 – 45 mm seeds are spaced at 20 – 25 cm apart giving about 60, 000 seeds/ha 45 -55 mm seeds are spaced at 30 – 35 cm apart giving about 40, 000 seeds/ha

Sowing the Seeds • Sown 10 cm below the surface of the ridge • Ridges should be 76 cm 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 – 55 mm 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: 50 g 200 g 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 - 25 cm 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 1 m 2 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 m 2 1 tonne = 1000 kg

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. 8 m in height • Easy access for tractors and trailers • Strong, reinforced walls Potatoes to be sold after February 1 st 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 p. H 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