Heads up About New Race of Downy Mildew in Lettuce

A newly identified race of Bremia lactucae, the pathogen responsible for downy mildew in lettuce, has been confirmed by the International Bremia Evaluation Board – United States (IBEB-US). Designated Bl: 10US, this race presents a new challenge to U.S. lettuce production, particularly in California’s Salinas and Imperial Valleys, where downy mildew pressure is consistently high.

Bl: 10US has emerged with strength, demonstrating the ability to overcome Dm25, Dm38, Design, and several other genes. This reinforces the importance of local research to address the pathogen’s well-documented capacity to evolve rapidly under selective pressure.

“With B1:10US recently named, we’re pleased to have several highly resistant varieties available now,” says  Julie Butcher, Product Manager, N&CA Open Field Whole Head Lettuce and Brassica for Enza Zaden. “We are also in the process of advancing more pipeline varieties as we continue to evaluate the impact of the new race and other emerging threats facing lettuce growers.”

While no crop can be guaranteed free from downy mildew, the combination of highly resistant varieties together with appropriate chemical protocols and preventive agricultural practices offers the most effective strategy for successful lettuce production.

For updates and more information, visit enzazaden.com.