The Netherlands
April 22, 2014
Bremia lactucae races BI:1-15 are no longer relevant and resistance to these races will not be claimed any more from September 1st 2014.
Bremia lactucae (Downy Mildew) is known to be a lettuce disease in which frequently new isolates appear. In August 2013 the IBEB has nominated 3 new races of Bremia Bl:29, Bl:30 and Bl:31. As a result of the successful introduction of an increasingly wide range of resistance genes by breeding companies, a clear trend is visible. Local isolates of Bremia appear which spread less fast than races nominated in the past. The three newly nominated races are not evenly spread over Europe and do not cause problems everywhere.
The International Bremia Evaluation Board, collecting and evaluating more than 200 isolates per year, is noticing another important trend during recent years. Several physiological races of Bremia lactucae in lettuce (races Bl:1-15) are agronomical no longer relevant in Europe. As to the best of our knowledge these races are no longer observed in practice.
Therefore reference to the races Bl:1-15 is no longer made in resistance claims in seed catalogues with regard to B. lactucae. From September 1st 2014 onwards, the resistance claim of a variety will only refer to Bl:16-31.
The IBEB consists of representatives of the Dutch and French seed business associations Plantum and UFS, and the organisations of GEVES and Naktuinbouw. IBEB is supported by several Bremia investigators across Europe. The business associations were represented by lettuce breeders of Agrisemen, Enza Zaden, Gautier, Nunhems, Rijk Zwaan, Monsanto Seminis, Syngenta and Vilmorin.
For testing and breeding purposes all nominated races and EU-B determination set are available at GEVES/SNES (France) and at Naktuinbouw (The Netherlands).
B-14-506
Gouda, April 22 2014
Subject: Final announcement letter and Press Release regarding BI:1-15
The International Bremia Evaluation Board has concluded that several physiological races of Bremia lactuca (races Bl: 1-15) are agronomical no longer relevant in Lettuce in Europe.
The IBEB is proposing that from September 1st 2014 onwards reference to the races Bl: 1-15 is no longer made in lettuce seed catalogues and other commercial communications. Resistance claims of Lettuce varieties will then only refer to Bl: 16-31. The IBEB has prepared a press release to be distributed by the end of April 2014 (See above).
The International Bremia Evaluation Board, consisting of representatives of the Dutch and French lettuce seed companies (Agrisemen, Enza Zaden, Gautier, Nunhems, Rijk Zwaan, Monsanto, Syngenta and Vilmorin) and the organizations of GEVES and Naktuinbouw, has come to this conclusion after careful consideration and in consultation with ESA and several lettuce companies that are not part of IBEB.
Lettuce seed companies will be able to prepare themselves properly for this change during the coming months. This will also change the communication of resistance claims in the market from September 2014 on.
This does not change the resistance test protocol for variety registration.
IBEB has prepared the following explanatory note. This text can be used in seed catalogues and other commercial communications to explain this transition to customers:
Physiological races Bl: 1-15 of Bremia lactucae (downy mildew) in lettuce are to the best of our knowledge no longer observed in practice in Europe nowadays. Therefore reference to the races Bl: 1-15 is no longer made in resistance claims with regard to Bremia lactucae. From September 1st 2014 onwards, the resistance claim of a variety refers only to Bl: 16-31.
Some companies prefer to mention also that race BI: 19 is also no longer observed. This might make the message to customers a bit more complicated and the current practice has not changed. If companies wish to mention it, then the following explanatory note can be used:
Although race Bl: 19 is to the best of our knowledge also no longer observed in practice nowadays, reference to the race Bl: 19 will continue to be made in resistance claims with regard to Bremia lactucae to simplify the notation of the resistance claim. In practice this means that for example Bl: 16-31 should be understood as Bl: 16-18,20-31.
Kind regards,
Henk Driessen
Chairman of the IBEB
Crop Research Director Leafy Vegetables
Phone direct: +31 (0)228 351 448/ Mobile: + 31 (0)651 339 449
Enza Zaden Research &Development B.V.
P.O. Box 7 1600
AA Enkhuizen , The Netherlands
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