New iceberg lettuce varieties with new Nasonovia resistance launched

Rijk Zwaan has introduced the first two iceberg lettuce varieties – Happinas RZ and Friendlinas RZ – with a high resistance against biotypes 0 and 1 of the extremely troublesome blackcurrant-lettuce aphid Nasonovia ribisnigri (Nr:0,1). This innovation by the Dutch fruit and vegetable breeding company is a very significant development for lettuce growers and their customers, especially in Europe.

© Rijk Zwaan

The new resistance creates an extra option in the battle against the blackcurrant-lettuce aphid. This is particularly important now that lettuce growers in the European Union (EU) will no longer be allowed to use systemic pesticides containing Spirotetramat as the active ingredient as of next season. "They are asking themselves how they can stay aphid-free," explains Peter Sonneveld, Crop Coordinator at Rijk Zwaan. Growers face substantial risks because lettuces affected by the aphids are virtually impossible to sell.

High resistance proven in field trials
Therefore, the new iceberg lettuce varieties – which are being marketed under the Nasonovia Defense label – have come at just the right time for growers. They represent a significant step towards futureproof lettuce production. The high resistance has been proven in multiple field trials by Rijk Zwaan over the past year. When disease pressure was high, susceptible lettuce varieties became heavily infested by blackcurrant-lettuce aphids. In contrast, the researchers found hardly any aphids in the high-resistance varieties in the same field.

© Rijk Zwaan

Positive agronomic traits
Moreover, the new iceberg lettuce varieties have positive agronomic traits. Trials at 20 growers' facilities in north-western Europe showed that the varieties perform well in terms of head shape, base, weight and strength against tipburn. "We're happy to share the details with growers," says Peter Sonneveld. Rijk Zwaan expects to have sufficient seeds of both iceberg varieties available for the upcoming season.

More lettuce types with Nr:0,1 resistance in the pipeline
Besides the iceberg lettuce varieties Happinas and Friendlinas, growers can expect to see varieties of other types of lettuce with the same resistance before too long. Johan Schut, Breeding Manager at Rijk Zwaan, explains: "Our team is busy crossing the resistance into other lettuce types for each market. Furthermore, our goal is to combine the Nr:1 resistance with the complete package of resistances against Bremia races and against the soilborne fungus Fusarium."

© Rijk ZwaanGrowers face substantial risks because lettuces affected by the aphids are virtually impossible to sell

Protecting the resistance
To help protect the resistance for the future, Rijk Zwaan advises growers to apply every aspect of Integrated Crop Management (ICM). Among other things, that means monitoring pests, using natural predators and biological pesticides, and controlling aphids with the chemical agents that are still permitted.

© Rijk Zwaan

Varieties on display during the Demo Days
Growers who would like to see the new Nasonovia Defense varieties for themselves are welcome to visit the Rijk Zwaan Demo Days this autumn. The Open Field Demo will be held in the Dutch town of Fijnaart from 15 September to 10 October. The varieties will also be on display during the Pfälzer Feldtag in Germany on 11 September.