Tests confirm that a ”significant portion” of the group’s lettuce portfolio shows high or intermediate resistance to Bl:38EU, Bl:39EU, and Bl:40EU

The International Bremia Evaluation Board for the EU (IBEB-EU) has announced three new Bremia races, Bl:38EU, Bl:39EU, and Bl:40EU, and said that tests by Enza Zaden have found a significant portion of its lettuce portfolio showed high or intermediate resistance to these races.

Romaine lettuce

The IBEB-EU also announced on 1 July the removal of BI:16-28.

Bremia lactucae, which occurs worldwide, causes downy mildew in lettuce and is genetically very variable.

It represents a great problem for the yield and quality of cultivated lettuce and, due to the high variability of the pathogen, there could be frequent mutations in the virulence genes, and newly emerging races could rapidly break the resistance genes.

After the test following IBEB-EU protocol, Enza Zaden concluded that it’s lettuce portfolio offered a wide range of solid varieties with ”excellent field performance, outstanding post-harvest quality, and high or intermediate resistance to Bremia”.

In combination with the usual preventive treatments, these varieties ensured a high level of protection, leading to successful lettuce production, the group said.

The International Bremia Evaluation Board for the EU (IBEB-EU) evaluates over 300 European isolates annually, focusing on lettuce varieties from breeders’ and growers’ fields.

They track the emergence of new races and the disappearance of known races.

Breeders are working together to monitor the changes in the Bremia population in response to the introduction of increased resistance.