Europe: Downy Mildew races BI:1-15 no longer relevant
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).
For more information, please contact:
SNES-GEVES France
Mrs. Valérie Grimault or Mrs Sophie Perrot
T: +33 (0)2 41 22 58 00
Valerie.Grimault@geves.fr or Sophie.perrot@geves.fr
Naktuinbouw Variety Testing department
Mr. Diederik Smilde, Mr. Richard Ludlage or Mrs. Amanda van Dijk,
T: +31 (0)71 33 26 213
Resistentie@naktuinbouw.nl
www.naktuinbouw.nl