Characteristics and Conductivity of Emamectin Benzoate-Inclusive Nanocapsule in Pinus massoniana Lamb.

To improve the conductivity of nematocidal emamectin benzoate (EB) in pine trees (Pinus massoniana Lamb.), EB-inclusive nanocapsules (EB-NCs) were developed as trunk injections and spraying agents. Microscopy revealed that the EB-NCs were spherical in shape (100-200 nm in diameter) and micro-agglomerated with an obvious core-shell structure. The EB-NCs formulation maintained high toxicity in Bursaphelenchus xylophilus pine wood nematodes (LC50 = 0.44 mg L-1). Moreover, the formulation had better EB slow-release and photostability. In addition, the EB-NCs formulation was effectively absorbed and transported in the pine trees via either trunk injection or spraying. In terms of trunk injection, the average residues of EB in the lower, middle, and upper branches of P. massoniana 30 days after application in summer were 8.11, 16.42, and 6.98 mg L-1. In terms of spraying treatment, the EB-NC formulation was successfully conducted from the cortical tissue to the cambium and the EB fluorescence intensity inside of the branches was better than that of the 2% EB micro-emulsion. The EB-NC formulation has suitable conductivity in pine trees; hence, this study provides a potential agent for the control of pine wilt disease in the field under all weather conditions.