Distribution of Bursaphelenchus lignicolus in the dead pine trees

Abstract

The investigation was conducted to obtain some basic data to examine an accuracy of the boring method by the distributional pattern of Bursaphelenchus lignicolus in the pine tree (Pinus densiflora S. et Z.) died from the infection of the nematode.The distributional pattern of the nematodes in the disks cut transversely from the 19-20 years old pine trees at one meter interval above the ground in October of the year was determined by the index of dispersion, 16, which was calculated from the number of nematodes per dry weight g of each divided block (2×2×2 cm) of the disks. The Iδ values were between 1.32 and 3.24 and indicated a contagious pattern. In the disks of the dead pine trees cut at four meters above the ground in May of the next year, the population density of nematodes was higher in the marginal part than in the central part and in the disks cut at the same height from the logs laid down above the ground for seven months after falling in October of the year, it was higher in the central part than in the marginal part. In the disks cut at two heights from the 83 years old pine trees which died in October of the year, the population density was much higher in the sapwood than in the heartwood.