The characteristics of oleoresin exudation amount from the trunks of pine trees

The amounts of oleoresin exudation from artificially-marked wounds on the trunks of pine trees were measured, and several characteristics of the oleoresin exudation amount (OEA) were elucidated. OEA showed no regular diurnal change and had no relation to both heights and directions of the wounds marked on the trunks, but differed between individual trees and between locations on the same tree. The exudation of oleoresin from each wound stopped after several hours. Mean OEA per wound decreased with increase in the number of wounds per given area. When the exudation of oleoresin from a wound was exhausted, further oleoresin was scarcely exuded even from a new wound made close to the initial one. In response to wounding, therefore, primary oleoresin exudation seems to occur by releasing the resin stocked in the resin canal.