Disclosed are methods for protecting a tree or plant or harvest product from acquiring a plant pathogen carried by insects through the application of pyroligneous acid composition diluted in water. The methods include subjecting a lignocellulosic biomass to a pyrolysis process and passing an exhaust gas of the pyrolysis process through a condensing column thereby producing the pyroligneous acid composition. The composition is applied to objects, areas, or the surfaces of trees or plants to repel the insects thereby minimizing production loss and preventing the tree or plant or harvest product from acquiring the plant pathogen.
