Among-tree difference in the inhibition of systemic dispersal of Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) by Pinus densiflora

Abstract

The among-tree differences in the inhibition of systemic dispersal of Bursaphelenchus xylophilus by Pinus densiflora were determined. Two-year-old branches were collected from four different aspects and at two different heights from six field grown P. densiflora. The virulent isolate of B. xylophilus, T-4, was inoculated on the upper end of 5-cm-long branch sections placed upright in a glass vial. The number of nematodes passing through the sections over 24 h was counted. Daily changes in the inhibition of systemic spread of the nematode were also determined. Two-year-old branches were collected at four hour intervals for 24 h from six additional trees. These branches were then inoculated with the nematode. The number of nematodes passing through the branch sections differed among the pine trees but did not differ between the branch heights or aspects. A diurnal change in the passing nematode number was observed only for a tree which grew on the top of a steep slope.