Japanese larch trees approximately 10 years old were inoculated with
Ceratocystis laricicola at the Experimental Forests in Yatsugatake, Agricultural and Forestry Research Center, University of Tsukuba, Kawakami-mura, Nagano Prefecture. After the inoculation, development of the external symptoms, size of lesions on the inner bark, staining and dried zones of sapwood, disturbance of water conduction in sapwood, development of
C. laricicola in sapwood and change of the xylem pressure potential of the inoculated trees were examined every week.
Ceratocystis laricicola grew in sapwood radially and longitudinally. Sizes of lesions on the inner bark and blue stained and dried sapwood increased with time. There was no water conduction in the blue stained and dried sapwood. The xylem pressure potential gradually decreased. The external symptoms appeared 14 days after inoculation and at this time some of the trees were already dead. Sapwood area in which water conduction was disturbed reached more than 85% in the transverse section near the inoculation point in the dead trees. Results of this experiment indicated that
C. laricicola grew in the sapwood and stopped water flow, and consequently external symptoms of the larch trees developed.
View full abstract