In the last couple of days, I received several calls about flatheaded borer in walnuts from various clientele up and down in San Joaquin Valley. Flatheaded borer has become a new issue in several young and mature walnut orchards in the past few years. I know we want to know what insecticides can be used to manage this pest. Unfortunately, there have not been any studies investigating the efficacy of insecticides to control this pest in walnuts. At the moment, the best line of thinking to manage this pest is to know the symptoms of flatheaded borer damage in walnuts, and follow winter cultural practices (i.e., removing the infested and dead branches from the orchard) to reduce the pest incidence and damage. For more information about Pacific flatheaded borer, it's biology, and management options, read this article that I wrote for the West Coast Nut a few months ago.
