The pallid nematode is the main and most dangerous pest of potatoes in the UK. About 65% of the country's land used for growing potatoes is infested with this pest.
Currently, a combination of the following methods is used to control nematodes: selection of pest-resistant potato varieties, increasing the area of crop rotation so that the crop returns to its original place no earlier than after 8 years and the use of environmentally unsafe chemicals.
As part of the Innovative Farmers program, four British farmers are working with scientists to explore an alternative nematode control method using plants known as trap crops, which naturally protect the plants from pests.
The chemicals released by the roots of trap plants signal the presence of suitable food and encourage nematodes to exit their cysts. The pests begin feeding on the roots of the trap plants, rather than on potatoes, even before the crop is planted. This method of control has a double benefit: by using a trap plant instead of an optimal potato host plant, nematodes cannot accumulate enough energy to reproduce and complete their life cycle, thereby reducing the likelihood of subsequent soil contamination.
Farmers sowed the seeds of the traps in late June and early July, shortly after the grain harvest, with the second sowing taking place one month after the first. Two types of traps were used - Solanum sisymbriifolium (sticky nightshade) and Solanum scabrum (African nightshade).
S. sisymbriifolium can reduce nematode density by up to 80%, but is difficult to grow in the field. The cultivation of S. scabrum is less studied in the UK, but there is a high likelihood that the plant is more suited to the country's climate.
Farmers and scientists suggested that a deeper planting could give a better result than a shallow planting, so they decided to experiment with two options for planting trap planting depths: 1,5 cm and 3 cm.
A tentative conclusion can now be made that sowing earlier, avoiding swampy soils and higher seeding rates are most effective. S. sisymbriifolium, sown to a depth of 1,5 cm, in different conditions and climatic zones of the country, gave the smoothest shoots.
Research on pallid nematode trap plants in the UK is ongoing.