Extractor for increment borer

An extractor for an increment borer for taking increment cores from trees, which borer consists of a tubular body, having an internal cylindrical portion which, at its forward end, transforms to a convergent conic portion, said borer being provided on its outer surface with screw threads for screwing the borer into a tree, characterized in that the extractor comprises a cylindrical tube, the outer diameter of which corresponds to the inner diameter of the cylindrical portion of the increment borer and the inner diameter of which corresponds to the smallest inner diameter of the increment borer at the forward conic end portion thereof, so that the extractor can be inserted into the borer over an increment core present in the borer, after the borer has been screwed into a tree, and that a bifurcation is located in the wall of the forward end of the extractor, so that the wall at said forward end is radially inwardly deformed plastically when said forward end is moved axially into and pressed against the said conic portion of the increment borer, and a guide plug adapted to be insertible into the rearward end of the extractor, said guide plug having a length dimension such that, when inserted in the extractor, its forward end will project into the increment borer when the forward end of the extractor is at the transition of the cylindrical portion of the increment borer to said conic portion.