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POTATO CULTURE

This information was compiled by Phil Cooper and originally posted by the Hamphire HDRA.
It was gleaned from HDRA and British Potato Council leaflets, Organic Gardening magazine and a talk given by Bob Sherman, the HDRA's Gardens Curator, at an HDRA potato day at Ryton.


Out of the 157 varieties of potatoes for which seeds are available in the United Kingdom, 30 are acknowledged as being commercially grown by the Potato Council, but 2/3 of earlies and of maincrops sold are from just 6 varieties! Organically grown potatoes have no chemicals used on them but the others are routinely treated against pests, weeds and diseases whilst growing and, at this time of year, the tubers are treated to prevent sprouting. Non-organic commercially grown varieties are selected for their ability to produce high yields in preference to flavour and organic producers have to rely on disease resistant varieties. The alternative is to grown your own (organically, of course). Currently, of the 157 varieties available as seed, 19 are available as organic seeds (See list of suppliers below). Having selected your seed what then?

Step One. Chit the seed. Set the seeds, eye end uppermost, in egg trays and place in a cool well lit spot to produce short fat sprouts.

Step Two. Plant choosing from the following methods:

Method A. Trenching. Dig a trench 1 spade deep and place farm yard manure*(FYM), at no more than 1 barrowload to 10 square yards in the trench, together with compost** and wilted comfrey leaves* as available. Place the seeds (sprouts pointing up!) 12" apart for earlies and 15"-18" apart for maincrop on the materials in the trench and cover with the soil removed from the trench. Ensure that the seeds are 2 - 2 times their diameter in depth below the surface. Trenches should be 2’ apart for earlies and 2’ apart for maincrop. As the leaves emerge, earth up to cover the emerging shoots by 2" -3", this will protect them from frost. Earthing up consists of making a low ridge of soil over the row by use of a draw hoe or spade so that the sprouts are just covered. When the leaves are 1’ high earth up again, this time to produce as high a ridge as possible using the soil between the ridges. To harvest dig up all the potatoes from each row using a fork. Any tubers, no matter how small, will miraculously survive the winter and grow again the following year.

Method B. No dig. Place FYM, compost, leafmould, wilted comfrey leaves, as for the trench method on the surface. Place the chitted seeds on the ground/material spaced 12" for earlies and 15" for maincrops. Cover with 1’ of hay, wet straw, leaf mould or grass cuttings. To harvest merely pull back the mulch and pick the potatoes as required.

Method C. Raised beds. Plant chitted seeds 2 - 2 times their diameter deep using a trowel or special potato planter. Space as for no dig. Cover with soil and mulch with materials as for no dig as the sprouts emerge; repeat the mulching until it is approximately 6" thick. Harvest as for trench method.

Method D. Under polythene (not encouraged by HDRA which is trying to cut down on the use of this material). Prepare grown as for no dig, place chitted seeds in the material, and cover with black polythene. When shouts appear to be pushing up the polythene, cut a cross in it to allow the sprouts through. Harvest as for no dig.

Method E. Container. fill a large container (12" wide to dustbin) or 2 stacked old tyres with a mixture of soil, FYM, compost, comfrey leaves as above. Place the chitted seeds on the mixture, approximately 3 in a car tyre, and cover with 2 - 2 times their diameter of the same mixture. Keep just covering the emerging shoots until the container is full or 4 -5 tyres are stacked. To harvest empty the container or remove the tyres.

Step Three. Enjoy the different flavours - Wendy is looking into producing some recipes for future editions of Compost Box.

Variations. Eyes. Cut a chip sized piece of material with at least on eye from the potato, allow to dry before planting as above.

Peelings. Potato peelings instead of whole potatoes may be used in any method

Compost. Grow entirely in compost using the no dig or trench method ("earth up" with additional compost).

Method Advantage Disadvantage
Trench Improves ground because of frequent movement of soil
Good protection from frost for earlies
Least additional material required
Hard work
Very easy to leave tubers in ground
Maximum susceptibility to eelworm and scab
No dig Less effort to plant and harvest than trenching or raised beds
Less chance of leaving tubers in ground
Lowers effects of scab and eelworm
Cleaner tubers
Mulch can be disturbed by birds causing tuber greening
Mice can get at easily crops
Earlies susceptible to frosts
Raised beds Less effort to plant than trenching
Reasonable protection against frost for earlies
Unlikely to be troubled by scab or eelworm
Mulch can be disturbed by birds
Requires high levels of fertility in the bed
Polythene Least effort to plant and harvest
Lowest risk of leaving tubers in ground
Lowers effects of scab and eelworm
Cleaner tubers
Cost of polythene
Mice can get at easily crops
Not suitable for earlies (risk of frost damage)
Blight easily transferred from leaves to tubers
Containers Can be fitted in small area
Extra early crops can be raised if container under cover
Can remove risk of slugs, eelworm and scab
Not suitable for earlies, whole container harvested at once
Large quantities of soil/compost required
Lots of watering needed

Problems.

Blight. This is a fungal infection that starts on the leaves and then spreads to the roots as the spores are washed down into the soil by rain. The problems is that blighted tubers quickly rot. The disease is less prevalent in dry summers and is also less likely to be washed down. Spraying with Bordeaux mixture will contain light infections which can be recognised by yellow blotches on the leaves. By the time the blotches are large and brown it is too late and the only treatment is to cut off and remove the tops. Note that the spores remove alive on the surface for up to 3 weeks. Do not harvest tubers you hope to keep during this period or the disease may well be spread to the tubers. Some varieties are less prone to blight than others.

Slugs. The slugs that cause the damage are keeled slugs. They are small, black and quite sneaky in that they live in the soil. There are no organic measures to prevent slug damage except the removal of material over winter that provide them with home and food. This is an added reason for removing all tubers when harvesting; similarly other root crops that remain in the ground, such as carrots and parsnip provide food and shelter. Although some varieties may claim to be less affected by slugs, as many growers will claim that a given variety is resistant to slug damage as will claim that it is ruined by the pests.

Scab. This disfiguring disease, which does not appear harm the crop, is worst in alkaline soils. Do not lime before planting potatoes. The incorporation of acidic material such as FYM, compost, grass mowings may improve your chances of avoiding the problem on a given variety. Some varieties are accepted as being less prone to scab than others.

Drought. Potatoes require adequate supplies of water, particularly when the tubers are forming, typically during the period 4-9 weeks after the emergence of the first sprout. More important, as the tubers develop, is that the availability of water is as even as possible. Large variations cause the skin to harden when the ground is dry then split when water becomes available again. If you do start to water, only water the ground not the foliage and do not subsequently allow the ground to dry out. Some varieties are noted as being less susceptible to drought than others.

Eelworm. There are 2 distinct types of this long lived soilborne pest which is only detected by low yields for no other reason. The best answer is not to try to grow potatoes in ground known to be infested. If this is not an option choose one of the varieties that are noted as being resilient to your type(s) of eelworm. Rotation may help but the pest survives for up to 20 years without its host. (You could ask the estate agent if the garden has the pest before buying a new house!). Good levels of humus and no dig methods may also reduce the impact of the pest.

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