News - March 29, 2007

Sticky nightshade almost ideal nematode killer

Fields infected with potato cyst nematodes can be biologically disinfected by growing sticky nightshade for a season. The trap crop is difficult to combine with other crops in the same growth season, however. Nevertheless Wageningen plant researchers see good opportunities on the international market for the nematode killer.

‘Of course we had hoped that sticky nightshade would be the perfect trap crop for potato cyst nematodes. Economically it is most attractive if you can combine the crop with another one, but in the Netherlands this is not likely to be feasible,’ says Dr Jan Vos, a researcher at the Crop and Weed Ecology group. The research that Vos did with Dr Bart Timmermans has been published in Annals of Applied Biology, and the results indicate that the growing season required for the nightshade is too long for other crops to be grown in combination with it. Vos: ‘The plant is permitted in green fallow, which means that Dutch farmers can get a subsidy for growing it for a season on a field infected with potato cyst nematodes.’

Nematodes are found in nearly all types of soil. They cause considerable harvest losses and are also responsible for indirect damage as it is forbidden to grow seed potatoes on fields that are infected with nematodes. Sticky nightshade (Solanum sisymbriifolium), a wild relative of the potato, attracts the potato cyst nematodes out of the protective reproductive structures (cysts) and therefore prevents them from multiplying.

The Dutch seed company Vandijke Semo has bred three varieties of sticky nightshade that can reduce the nematode population in the field by 60 to 75 percent. This effect is almost as great as that achieved by chemical soil fumigation.
The sticky nightshade also produces a good leaf harvest, but a use for this has not yet been developed. Vos: ‘By the end of the season the plants are almost as tall as a man. The dry mass is high, so there might be possibilities in the biomass direction.’

The growth simulations carried out by Timmermans and Vos indicate that the crop does better in a slightly warmer continental climate than in the Netherlands. ‘There would seem to be good potential for potato growers in Poland.’