The cork must, however, be extracted from the trees without causing any lasting harm to them – otherwise, nine years later they will be useless.  Extraction takes place in the summer when the tree is least susceptible to damage. The poor cork which is produced as a result of the first two harvests is known as male cork: later extractions provide what is known as gentle cork which is what you will screw out of the wine bottle, the contents of which it helps to flavor.