Happinas RZ and Friendlinas RZ the first of several blackcurrant-lettuce aphid-resistant varieties being developed by the company
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 blackcurrant-lettuce aphid Nasonovia ribisnigri (Nr:0,1).
The Dutch fruit and vegetable breeding company hailed it as a very significant development for lettuce growers and their customers, especially in Europe.
The new resistance provides an extra weapon 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.
Growers face substantial risks because lettuces affected by the aphids are virtually impossible to sell. “They are asking themselves how they can stay aphid-free,” said crop coordinator Peter Sonneveld.
Rijk Zwaan said the new iceberg lettuce varieties – which are being marketed under the Nasonovia Defense label – represent a significant step towards futureproofing lettuce production.
The high resistance has been proven in multiple field trials carried out by the company 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,” the company said.
Moreover, the new iceberg lettuce varieties have positive agronomic traits. According to Rijk Zwaan, trials at 20 growers’ facilities in north-western Europe showed that they perform well in terms of head shape, base, weight and strength against tipburn. “We’re happy to share the details with growers,” Sonneveld said.
Rijk Zwaan expects to have sufficient seeds of both iceberg varieties available for the upcoming season. It is also developing varieties of other types of lettuce with the same resistance, which will shortly be available on the market.
Breeding manager Johan Schut commented: “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 Bremiaraces and against the soilborne fungus Fusarium”.
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 said growers who would like to see the new Nasonovia Defense varieties for themselves are welcome to visit the company’s 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.
