There are no pesticides available to home gardeners which will control potato cyst eelworms, and so cultural methods should be used to avoid spreading the pest and to reduce infestations.
A high population of cysts may soon develop if potatoes or tomatoes are grown frequently in the same piece of soil. This can be avoided by adopting as long a rotation as possible. Self-set or 'volunteer' potatoes can maintain an infestation and so weed them out in early summer before eelworms can complete their development. Eelworm eggs can survive for up to ten years in some soils and so very long rotations are needed to starve out the pest completely. This process can be speeded up by sowing a half-hardy annual, Solanum sisymbriifolium. This plant’s roots induce egg hatching but eelworms cannot develop in the roots. Suppliers can be found via RHS Find a Plant.
A worthwhile crop of early potatoes can usually be grown in infested ground after a break of five or six years. The increase in cyst numbers can be limited by lifting the crop as soon as the tubers are ready and not allowing the plants to continue growing beyond that point.
There are some potato cultivars that have resistance to the golden cyst eelworm. These include;
Accent, Lady Christl, Pentland Javelin, Premiere, Rocket, Winston (earlies), Blue Danube, Kestrel, Nadine, Saxon (second earlies), Cara, Maris Piper, Maxine, Nicola, Picasso, Sante, Stemster, Valor (maincrop)
The root exudates produced by these cultivars still induce egg hatching and the roots are attacked in the usual way. Females, however, are unable to develop inside the roots and only males are produced, thus reducing the number of eggs in the soil. White cyst eelworms can reproduce normally on these varieties. Crop rotation is still important, even in areas where the golden cyst eelworm predominates, as there is a danger that the other species may also be present and will increase in numbers if potatoes are grown too frequently.
Some cultivars also have some tolerance of white cyst eelworm, in addition to resistance to golden cyst eelworm. These include;
Harmony, Kestrel, Lady Balfour, Maxine, Sante, Valor
The white cyst eelworm is able to complete its normal life cycle and reproduce in the roots of these varieties, but they are nevertheless able to produce a worthwhile crop, provided the soil is not heavily infested.
Hygiene and waste disposal
Once soil becomes infested with cysts it is difficult to prevent them being spread around the garden, but steps should be taken to avoid this occuring in large scale. Sanitize all equipment and shoes that came in contact with the infested soil, dig out roots and weeds from the infested plots but remember not to put them on the compost heap.
Soil that has grown potatoes should never be used in the greenhouse for growing tomatoes. If greenhouse beds become infested, the problem can be overcome by complete re-soiling, or by growing tomatoes in raised beds, growbags, or other systems, such as ring culture, or straw bales, which reduce root contact with the infested soil.