Developing Fluopyram as a Tool to Combat Beech Leaf Disease in Managed Landscapes and Nurseries

Beech leaf disease (BLD), caused by the anguinid nematode Litylenchus crenatae mccannii (Lcm), has recently emerged as a severe threat to beech trees (Fagus spp.) in eastern North America. In response, the scientific community has accelerated research on this invasive plant-parasitic nematode (PPN). Advances in BLD pathophysiology can be useful for developing management strategies. However, characteristics of both the pest and host trees make BLD uniquely challenging to manage, leaving arborists, nursery managers, and plant health care specialists with limited treatment options. The first treatment demonstrated to directly affect Lcm and suppress BLD was a late-summer foliar application program using fluopyram. These three sequential field trials explore several variables that must be determined when developing a novel management program: site appropriateness, product dosage, and the timing of foliar applications. The results support the efficacy of fluopyram-based programs in suppressing BLD but emphasize the importance of site conditions, noting that dense beech forests are unlikely to benefit from this treatment. The results also show that significantly reduced product doses can yield excellent control. Finally, the findings suggest that initiating the foliar application program earlier in the summer could be equally or more effective than beginning in late summer. This information will guide the implementation of novel management programs tailored to address the growing threat of BLD.