Nasonovia Defense™: High resistance as a building block for future-proof lettuce production

The pressure from currant-lettuce aphid (Nasonovia ribisnigri) remains a key concern for lettuce growers. At the same time, the range of available crop protection products continues to decline, increasing the need for sustainable alternatives. With Nasonovia Defense™, the label for lettuce varieties with high resistance (HR) to Nasonovia ribisnigri Nr:0,1, Rijk Zwaan is taking an important step forward. "We are very pleased with this resistance," says lettuce Crop Coordinator Peter Sonneveld. "It makes life easier for growers and provides an additional tool for managing aphids."

Supporting growers with a complex challenge

As Lettuce Crop Coordinator, Peter acts as the link between the market, growers and breeding. In this role, he closely monitors the challenges growers face and how new varieties can help address them.

Resistances have played an important role in lettuce production for many years. Bremia (downy mildew) is a good example, with new physiological races emerging continuously. Resistance to Nasonovia ribisnigri has also proven not to be permanent. The original resistance against Nasonovia Nr:0 was overcome several years ago, making the search for new resistance sources essential.

"Finding new sources of resistance was a major challenge. Thanks to many years of breeding efforts, we have been able to develop this resistance and make it available to growers."

Working together to maintain durable resistances

The introduction of Nasonovia Defense™ creates new opportunities for lettuce growers. At the same time, Peter emphasises that past experiences demonstrate the importance of deploying resistances carefully and sustainably.

The original Nr:0 resistance provided protection against currant-lettuce aphid for many years until the aphid adapted. According to Peter, this highlights why the sector should not rely entirely on a single solution. After all, nobody in the chain accepts aphids in lettuce: not the grower, not the processor, not the retailer and ultimately not the consumer. That is why it is important to use new resistances as sustainably as possible, helping them remain effective for the long term.

According to Peter, the real strength of Nasonovia Defense™ lies in an integrated approach. "The resistance is not the solution; it is part of the solution."

For this reason, Nasonovia Defense™ fits well within the principles of Integrated Pest Management (IPM). Growers combine resistant varieties with crop monitoring, natural enemies and other cultivation measures. This reduces dependence on any single solution and increases the likelihood that resistances will remain effective over time.

From breeding to commercial practice

In 2025, the first iceberg lettuce trials featuring commercially promising Nasonovia Nr:0,1 material were planted in the field. These trials eventually resulted in the varieties Happinas RZ and Friendlinas RZ, which are now being grown successfully in commercial production.

The positive market response is not based solely on the resistance. In terms of weight, crop health and product quality, both varieties also meet growers' expectations.

Continuing to invest in new solutions

Development does not stop with Happinas RZ and Friendlinas RZ. From this season onwards, Rijk Zwaan also offers iceberg lettuce varieties with a complete resistance package against both Nasonovia Nr:0,1 and Bremia Bl:29-41EU. In addition, the resistance is gradually being introduced into other lettuce types.

"We are only at the beginning of this development, but progress is moving quickly. The first breeding lines are already in the field, and we expect new commercial material in other lettuce types carrying this resistance to become available to growers as early as next year."

New challenges, such as Fusarium in various production regions, also require continuous innovation. That is why Rijk Zwaan continues to invest in solutions that support growers in overcoming the challenges of today and tomorrow.

Working together towards future-proof lettuce production

For Peter, the key message is clear: "We need to keep talking and working together to achieve a total solution."With Nasonovia Defense™, Rijk Zwaan introduces a new generation of lettuce varieties with high resistance to Nasonovia ribisnigri Nr:0,1. Combined with Integrated Pest Management, it provides growers with a valuable building block for resilient and future-proof lettuce production.

Want to learn more? Visit our Demo Weeks from weeks 38 to 41 and discover the latest developments in lettuce and Nasonovia Defense™ in practice.