Spatiotemporal dynamics of fluopyram trunk-injection in Pinus massoniana and its efficacy against pine wilt disease.

ABSTRACT

BACKGROUND: Pine wilt disease (PWD) is a destructive disease of pine trees caused by the pinewood nematode, Bursaphelenchus xylophilus. Fluopyram, a novel nematicide compound with systemic activity, is a prospective trunk-injection agent against pinewood nematodes. The disadvantage of current trunk-injection agents is that they were not evenly distributed in tree tissues and were poor in the persistence of effect and efficiency. Therefore, we investigated the spatiotemporal transport pattern and residue behavior of fluopyram following its injection into the trunk of Pinus massoniana. RESULTS: Fluopyram transport in the trunk occurred through radial diffusion and vertical uptake within 1 week of the injection, reaching all tissues of P. massoniana, including apical branches and needles. Three years after the field test, the infection of PWD declined substantially with treatment using the fluopyram trunk-injection agent, which demonstrated 100% efficacy in both the mild and moderate occurrence areas, and 71.1% efficacy in the severe occurrence area. Fluopyram as trunk-injection agent exerted substantial control over PWD, with its efficacy being influenced by the infection time of PWD. The half-life of 10% fluopyram in treated pine trees was 346.6 days with 3-year persistence. CONCLUSION: The advantages of overall distribution and long persistence of fluopyram in the tree after injection help explain its evident efficacy against PWN. Overall, fluopyram trunk-injection has potential to prevent PWD. © 2023 Society of Chemical Industry.