Almond growers across California’s Central Valley are being urged to stay alert for almond red leaf blotch, a disease that is becoming more common in orchards and can significantly impact tree health and yield if left unmanaged. Todd Burkdoll, Field Market Development Specialist with Valent USA, discusses the growing concern and management strategies in today’s Growing Edge segment.
According to Burkdoll, almond red leaf blotch is a monocyclic fungal disease, meaning it typically completes one infection cycle each year during the spring. The pathogen overwinters on infected leaves left on the orchard floor, producing spores that move into the tree canopy as conditions become favorable. Infections often begin around petal fall, slightly earlier than some other almond diseases growers may be more familiar with.
Symptoms primarily appear on leaves as distinctive burnt orange spots that expand over time. Multiple lesions may form on a single leaf, eventually causing leaves to dry and fall from the tree. Severe infections can lead to substantial defoliation, with some orchards experiencing as much as 40–50 percent leaf loss.
The loss of leaf area reduces carbohydrate production needed for nut production. Burkdoll noted that maintaining healthy foliage is critical to sustaining orchard productivity year after year.
Moist conditions play a major role in disease development. Rainfall during bloom and high humidity can create ideal conditions for infection, particularly on young leaves that are more susceptible to pathogens. Early-season monitoring and timely fungicide applications around bloom and petal fall are important steps in managing the disease.
Cultural practices can also help reduce disease pressure. Winter sanitation, such as blowing berms, mowing, and incorporating leaf debris into the soil, can reduce overwintering inoculum in the orchard. Preventive[MS1] management combined with effective fungicide tools like Quash® Fungicide can help growers protect trees and maintain productivity.
For more information, visit Valent.com/Quash.