Thiabendazole as a Therapeutic Root Flare Injection for Beech Leaf Disease Management

Abstract

Background: Thiabendazole (TBZ) has long been used in the arboricultural industry for tree injections as a key management tool of Dutch elm disease and sycamore anthracnose. This active ingredient is systemically distributed throughout the canopy and can offer multiple seasons of protection from these diseases. Well-studied in anthelmintic medicine, TBZ and other benzimidazole chemistries can be potent nematicides beyond their fungicidal use, disrupting microtubule assembly during mitosis with site-specific binding in some parasites. These nematicidal properties of TBZ allude to its potential in the management of beech leaf disease (BLD), caused by the foliar nematode Litylenchus crenatae mccannii (Lcm). Methods: To test TBZ for BLD management, symptomatic beeches were injected in Aurora and Chardon, OH, and Hillsborough, NJ. Treatments were evaluated using a combination of late-season dormant bud nematode counts and year-over-year change in canopy density and BLD symptom expression. Results: After 11- and 22-months post-treatment, trees significantly improved based on visual ratings, and Lcm was reduced in dormant buds of TBZ injected trees, while nontreated controls continued to have high disease severity and large numbers of Lcm in dormant buds. An injectable TBZ treatment for beech trees offers a new mode of action and application method against Lcm and a more appropriate tool where foliar applications are impractical or where environmental exposure is of concern. Conclusions: This study introduces a novel and effective tool that can be utilized in an integrated pest management program for BLD.