14 



If the branches are of good size they are treated in the same manner 

 as the trunk. Care must be taken not to denude too much of the trunk 

 at once, as that will endanger its life. Therefore each tree is managed 

 so as not to expose in the same year more than one zone of mother 

 layer, alternating the harvest among the trees. (See PL III.) The 

 mother layer is liable to damage from exposure as well as from insect 

 enemies, among which are the red ant {Formica liguiperda), the larva 

 of Corcebus undatas (Corch), and also from various fungi. 



Notwithstanding the care that is taken, there occurs from the una- 

 voidable exposure of the mother cork a loss of trees amounting to 2 per 

 cent after each decortication. Besides, there is a loss of 15 to 18 per 

 cent of cork by the furrowing of the cork layer, due to dryness and 

 also sand and dust blown against it and embedded, a considerable 

 layer thus becoming useless. To avoid these losses it is proposed to 

 cover the mother layer, using for the purpose the cylinders of "wild" 

 cork attached by wire, closing their open sides with tar paper. This 

 method is claimed by the originator (Capgrand-Mothe) to double the 

 yield, but its practicability is doubted by others. 



The question as to the age a cork oak must attain before the first 

 barking is difficult to answer, as during the early years the cork oak is 

 capricious as to its development; often a tree can be barked at 20 years, 

 while another growing by its side would be 30 years of age before 

 being sufficiently mature. Size is the only true guide. Many cork 

 workers advise the first cutting to be made when the tree has attained 

 a measurement of 12 inches in circumference 3 feet from the ground; 

 others think it better to wait until the tree is 20 inches in circumference. 

 These are extreme opinions. 



The following progress may occur in a cork plantation regulated for 

 a series of annual harvests (see PI. Ill) : 



First period. Take a tree 14 to 16 inches in circumference that has 

 been barked to a height of 30 inches. At the expiration of a period 

 of from six to eight years the tree will measure from 18 to 21 inches in 

 circumference, and will furnish the first harvest of cork to a height of 

 30 inches; at the time of gathering the cork the outer bark should be 

 removed to a height of 18 inches above the last cut. 



Second period. Six years after the first harvest the outer barking 

 should again be extended 24 inches above the last cleared portion. At 

 the expiration of the period for ripening, the tree will measure from 24 

 to 30 inches in circumference at the last barked portion. The cork 

 may be gathered up to 48 inches from the ground. 



Third period. Six years after the second harvest it is possible to 

 detach the cork from the surface that was prepared during the sec- 

 ond period, and at the same time another surface 24 inches higher 

 should be barked. At the expiration of the period of development the 

 new cor! can be harvested from a surface 48 inches from the bottom 

 of the ;e upwa 1 ; the measurement will be from 30 to 36 inches in 

 circumi ~ence. 



