Denomination of new official downy mildew race in lettuce

On 1 July, the European committee of the International Bremia Evaluation Board (IBEB-EU) published the denomination of a widely occurring new race of downy mildew in lettuce: Bl:41EU.

New officially denominated race

Downy mildew can affect lettuce leaves in both protected and open-field crops, resulting in a loss of yield. A new variant of downy mildew (Bremia lactucae or Bl) has been found across Europe. This race has received the denomination BI:41EU.

IBEB-EU expects BI:41EU to continue to spread in the summer and autumn of this year, although it is currently difficult to predict the extent of the impact in specific areas. Rijk Zwaan’s crop specialists are happy to advise growers with detailed information about the company’s range of lettuce varieties and their resistances.

Over 500 lettuce varieties have been developed at Rijk Zwaan’s research and breeding station in the Netherlands, tailored to diverse growing methods and environmental conditions.

Sustainable solutions

Rijk Zwaan strongly advocates for integrated pest and disease management to minimise the risk of plant disease outbreaks. While resistant varieties play a crucial role, the company also recommends the restrained use of appropriate crop protection agents to prevent the development of new downy mildew variants. Furthermore, the implementation of good hygiene practices, such as removing diseased crops and promptly ploughing in crop residues, can help reduce the spread of downy mildew in lettuce.

International Bremia Evaluation Board

The International Bremia Evaluation Board (IBEB) is a joint initiative of lettuce breeding companies in the USA, France and the Netherlands, as well as the USA’s University of California-Davis, the Netherlands’ Inspection Service for Horticulture (Naktuinbouw) and the French National Seed Station (GEVES). IBEB’s mission is to identify new races of Bremia lactucae that pose a significant threat to North American or European lettuce production and to promote the use of standardised race names in communication with growers.

Races are identified and nominated by regional IBEB committees specifically for each continent. For more information, visit the International Seed Federation’s website.