Almond growers across California are continuing to monitor the spread of almond red leaf blotch, a disease that has increasingly appeared throughout the Central Valley in recent years. In today’s Growing Edge segment, Todd Burkdoll, Field Market Development Specialist with Valent U.S.A., says research trials are helping growers better understand how to manage the disease effectively.
University and independent trials have examined numerous fungicide options for controlling red leaf blotch. Research led by UC scientists has helped clarify the biology of the disease and identify key control strategies, including the importance of early treatment timing. According to Burkdoll, infections typically begin on young leaves shortly after bloom, making petal fall and the period immediately following bloom critical for prevention.
Trials evaluating roughly 20 fungicide products found several options that provided strong control of the disease. Among the top-performing products was Quash® Fungicide, which demonstrated preventive activity against red leaf blotch. “Quash came out at the top of the list,” Burkdoll said, noting it performed statistically similar to other top-performing fungicides tested in the trials.
Quash has long been used in almond disease programs, particularly for Alternaria control, but Burkdoll noted that its broad spectrum of activity also makes it effective against multiple pathogens including scab, rust, and blossom blight. This broad activity allows growers to manage several disease threats with a single application when timed correctly.
Proper fungicide rotation remains an important part of resistance management. Burkdoll emphasized the importance of rotating products from different FRAC groups rather than repeatedly applying the same chemistry. Doing so helps preserve the effectiveness of available tools and reduces the risk of resistance development.
Application practices also play a major role in performance. Using full labeled rates and ensuring thorough spray coverage throughout the canopy are key to achieving reliable disease control.
For more information about managing almond red leaf blotch, visit Valent.com/Quash.