Anatomical Response and Recovery of Twigs of Juglans Nigra Following Oviposition Injury Inflicted by The Two-Spotted Treehopper, Enchenopa Biontata


  • J. E. Armstrong
  • W. H. Kearby
  • E. A. McGinnes, Jr


Juglans nigra, wound repair, compartmentalization, periderm formation, anatomy


Ovipositor wounds on one-, two-, and three-year-old twigs of black walnut were examined. The ireehopper's ovipositor makes a longitudinal wound, which curves tangenlially through the bark splitting the tissues along the cambial zone of first year twigs. Following oviposition in August to early October, there is some proliferation of wound periderm and callus tissue surrounding the wound. Following nymph emergence in May. extensive callus formation and cambial activity closes the wound and reestablishes the continuity of the vascular cambium. Third-year growth produces normal secondary xylem: externally a corky scar remains.


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