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Tennessee State University helps to manage flathead borers

Impacts from the 1890 research program submitted by scientists at Tennessee State University

The flathead borer is a beetle that attacks nursery, nut, and orchard trees/shrubs from coast to coast – crops that account for millions of jobs and billions of dollars in economic impact. Managing these destructive pests has been a long-time challenge for producers. But thanks to a multi-state, multidisciplinary research and outreach initiative led by Tennessee State University (TSU), there’s hope on the horizon.

With Drs. Karla Addesso and Jason Oliver of TSU’s Otis L. Floyd Nursery Research Center are at the helm, and the initiative includes 24 researchers from across the nation. They are focused on flat-headed borers in the genus Chrysobothris, a native complex of species found across the U.S. that lays its eggs in the trunks of trees. The larvae feed on vascular tissue, disrupting the movement of water and nutrients, causing trunk scars, bark shedding and splits, suckering, sap leakage, crown dieback – and, for smaller trees, ultimately, the tree’s death. In the southeastern U.S. alone, Chrysobothris is responsible for more than 40% of losses in some nursery tree species.

Producers need better tools for managing flat-headed borers, and the TSU-led initiative aims to deliver. Funded by a $6 million grant from the USDA-NIFA Specialty Crop Research Initiative, its results will fill key knowledge gaps and develop best practice management tools. The work’s targets are a better understanding of Chrysobothris, more reliable ways to identify the species and trap it, more effective practices to reduce attacks and more effective chemical/biological management strategies that meet cost-benefit and social acceptability standards important to producers and consumers.

Some of the notable progress achieved thus far includes the following:

  • In efforts to develop genomic resources for more than 64 species of Chrysobothris, researchers have built phylogenies using more than 1,630 nuclear genes and 12 mitochondri-al genes. In 2023, the new COX1 primer was used to diagnose a novel pest relationship of Pacific Flat-headed Borer larvae (C. mali) found to be infesting pear fruit in California orchards – the first time a Chrysobothris species has been observed infesting fruit instead of wood.

  • The work to create better traps has resulted in the development of a “trunk mimic” design that has increased the trap capture of Chrysobothris while reducing the by-catch of other wood-boring beetles.

  • Optimizing a system to apply pesticides to only the tree trunks, researchers have been able to re-duce overspray between trees and canopies and off-target effects. By reducing spray volume by 30%, they also delivered savings to growers.

  • Trials showed that using in-row winter cover crops of crimson clover and triticale protected red maple trees to the same level as systemic drenches of imidacloprid.

  • Preliminary results suggest irrigating first-year transplants can protect red maple trees from attacks.

For more information, please contact Dr. Karla Addesso (; 931-815-5155).

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