1 July 2023

Three new races of Bremia lactucae, Bl: 38EU, Bl: 39EU and Bl: 40EU identified and denominated in Europe

Nunhem, 1 July 2023 | Source: Plantum

Bremia lactucae, or downy mildew, is a common plant disease in lettuce. This fungus can have a major impact on lettuce cultivation. Bremia lactucae, the causal agent of downy mildew in lettuce, is genetically very variable. Even within one lettuce production field, several races may be present. 

The IBEB-EU evaluated Bremia lactucae isolates found in Europe in 2021 and 2022 and concluded that three candidate isolates provided consistent test results. The IBEB-EU decided to denominate these variants as Bl: 38EU, Bl: 39EU and Bl: 40EU.


For more detailed information about Bl: 38EU, Bl: 39EU and Bl: 40EU, please download the official press release of IBEB-EU.

BASF resistances in lettuce

Lettuce is a key crop in Nunhems portfolio. Providing best in class solution to our customers is always our priority.  Bremia lactucae resistance is a key trait in our lettuce breeding program. Together with our Breeding and R&D team we are continuously monitoring the development of Bremia and looking for new resistance sources. These efforts help us to offer a reliable Bremia resistant portfolio to our customers. Next to genetic resistance, BASF wants to emphasize the importance of an integrated crop management. The combination of genetic resistance together with suitable chemical protection should deliver a good crop that is clean of Bremia.

BASF offers a wide range of lettuce varieties with a broad resistance pattern. Updated resistance information of the lettuce assortment can be found in the lettuce crop tables on our website.

Resistance to Bremia lactucae races Bl: 16-28EU will not be claimed any more in commercial communications from July 1st 2023

IBEB-EU is collecting and evaluating more than 300 European isolates per year. Commercial resistance claims of resistance for races that were important in the past but not in the present time are not relevant for growers. In recent years, Bl: 16-28EU were no longer found. Therefore, IBEB-EU proposes the following disclaimer in seed catalogues and other commercial communications:

The races Bl:16-28EU of Bremia lactucae (downy mildew in lettuce) are hardly observed in practice in Europe anymore and thus have no value for describing resistance levels to the disease. Therefore, from July 1st, 2023, onwards, commercial resistance claims for lettuce varieties will refer only to Bl: 29EU and races with a higher number, and no longer to races Bl: 16-28EU.

For more detailed information about Bl: 38EU, Bl: 39EU and Bl: 40EU, please download the official press release of IBEB-EU.


For more detailed information about Nunhems lettuce varieties and their resistance patterns, please contact the lettuce sales specialist at BASF’s vegetable seeds business.



Last Update 1 July 2023