Development of Composite Microbial Products for Managing Pine Wilt Disease in Infected Wood Stumps

Wood-decay fungi, including white- and brown-decay fungi, are well known for their ability to degrade lignin and cellulose, respectively. The combined use of these fungi can increase the decomposition of woody substrates. Research has indicated that these fungi also exhibit inhibitory effects against <i>Bursaphelenchus xylophilus</i>, the causative agent of pine wilt disease (PWD). In this study, we investigated a composite microbial formulation that efficiently decomposes pine wood while inhibiting <i>B. xylophilus</i>. We initially established a correlation between the degradation rate of wood blocks and fungal biomass, underscoring the necessity of optimizing biomass for effective treatment. A systematic approach involving a one-way test, a Plackett-Burman design, a steepest ascent experiment, and a Box-Behnken design, was employed to optimize the fermentation process. Validation trials were conducted in a 10-L fermenter. The bioagent's efficacy and safety were assessed through field applications in a forest, with a focus on wood degradation capacity and <i>B. xylophilus</i> mortality rate. Additionally, the environmental impact of the microbial products was evaluated by analysing soil quality around treated areas to ensure that the formulation did not adversely affect soil health.