Abstract:

Recently more and more evidence confirmed that pine wilt disease were caused by both Pine Wood Nematode and its carrying bacteria. Dynamics of population of nematode, variety and the quantity of bacteria in non-inoculated branches along with the process of the disease were observed firstly through inoculated with Pine Wood Nematodes onto testing Black Pine trees. In non-inoculated branches, bacteria could be detected when few pine needles became yellow; while most needles changed into yellow or brown, nematode could be isolated and the quantity of bacterium was increased; in the end, when the testing tree was dying and needles were totally wilted, the populations of both nematode and bacteria were increased rapidly. According to the identification of the bacteria isolated from the testing trees, the numbers of the isolated bacteria species were small, only a few, at the first and the middle stages. As the disease was developing, bacteria increased not only in their quantity, but also in amount of species. However, the domination species remain the same, they are Pseudomonas fluroescens, Pseudomonas sp.Acinetobacter sp., Pantoea sp. and Sphimgomenas pancimobilis.

Key words: Pinus thunbergii, Bursaphelenchus xylophilus, Pathogenic process, Pseudomonas sp.