16 May 2024, Netherlands: A new race of the downy mildew pathogen (Peronospora effusa) on spinach has been denominated by the International Working Group on Peronospora in spinach (IWGP), based on a worldwide evaluation of isolates from growers’ fields and trap nurseries. This was a strong candidate for nomination due to its significant threat to the spinach industry.
Race Pe: 20 poses a significant threat to the spinach industry worldwide, and resistance to this new race is important. The stable performance of isolate RZ2331B, first found in France, has been confirmed in validation tests by all IWGP members and renamed as reference isolate Pe: 20. A new differential cultivar was added to the differential set to distinguish Pe: 20 from races Pe: 1 to Pe: 19. Rijk Zwaan’s spinach program already includes a selection of varieties resistant to Pe: 20.
Broad range of Rijk Zwaan spinach varieties
Our broad range of spinach varieties and genetics give you the possibility of optimal mildew resistance. For the most up-to-date information on varietal performance and mildew resistances, we recommend that growers speak to their local sales representative.
Integrated resistance management
Rijk Zwaan prefers an integrated approach to resistance management; resistant varieties are a large part of this, but disease controls and hygiene measures are also important to help prevent the development of new mildew races. Proper hygiene practices, such as the removal of debris and diseased plants, will reduce the spread of mildew in crops.
About IWGP
The International Working Group on Peronospora in spinach (IWGP) continuously monitors the appearance of strains of the pathogen that deviate in virulence from the known races. In this way, the IWGP aims to promote consistent and clear communication between public and private entities, such as the seed industry, growers, scientists, and other interested parties, about all resistance-breaking races that are persistent enough to survive over several years, occur in a wide area, and cause significant economic impact.
Sector collaboration
The IWGP operates internationally and is administered by Plantum, located in The Netherlands. The IWGP consists of representatives from spinach seed companies (BASF, Bayer, Bejo, DeSeed, Enza, Pop Vriend, Rijk Zwaan, Sakata, Syngenta, Takii, and Vilmorin) and Naktuinbouw, and is supported by public research at the University of Arkansas. Spinach researchers worldwide are invited to join the IWGP initiative and use the common host differential set to identify new isolates. All denominated isolates and seeds of the differential set are available at Naktuinbouw (The Netherlands).
