Kino vein formation in Eucalyptus globulus and E. nitens

Kino veins or pockets are characteristic defects of some Eucalyptus species and have long been recognised as sources of degrade in eucalypt timber. In order to investigate the causes of kino vein formation, the short-term responses of Eucalyptus globulus and E. nitens to mechanical, chemical (2-choroethyl-phosphonic acid) and biological wounding treatments were examined. With the exception of the chemical treatment, the various wounding treatments did not consistently induce kino vein formation in either species. Instead, the new wound-associated wood and bark formed after wounding was characterised by the presence of dark extractives for both species. Although the dark extractives appeared similar to kino, microscopic examination showed they were formed in the less organised wound tissue and not in specialised kino veins. We suggest that the induction of tree exudates is part of a non-specific wound response and not necessarily a direct host response to invasion by microbial pathogens and insects.