708 FRUIT rui/ruKK IN FORKIGN COUNTRIES. 



not to remove any more bark than is absolutely necessary ; and for the 

 removal of shoots and twigs pruning-shears are to be used. In regard 

 to the best time for pruning, the custom varies in different districts. 

 Some writers on the subject contend that if pruning is effected when the 

 sap ascends in the spring the healing process is more rapid 5 others are 

 of opinion that it is best to prune at the end of winter and before the 

 sap has begun to move upwards. It is, however, universally admitted 

 that pruning is only to take place after the fruit has been collected and 

 before budding has begun. Thorough pruning is generally only done once 

 every two or three years, and as the pruned trees give a smaller yield 

 the first year after the operation, it is well to divide the trees into two 

 or three classes, one of which is pruned and trimmed every year, thus 

 dividing the work and equalizing the annual yield. 



As a direct means of stimulating the production and ripening of fruit 

 the practice of "ringing" is recommended. The process consists in 

 removing an annular strip of bark, varying from one-half to 1J centi- 

 meters in width, from the base of secondary or tertiary flower-bearing 

 branches, thereby preventing the descent of the sap, which is thus 

 utilized for the formation of fruit. This operation, which must be per- 

 formed when the tree has begun to blossom, but before the flowers are 

 fully expanded and fecundation has begun, is of great usefulness with 

 varieties that are given to u off years," or to exuberant flowering not 

 followed by bearing. Individual trees, as well as varieties bearing 

 scantily and irregularly, have been made to yield both plentifully and 

 regularly by this process, which, however, like all pains-taking prac- 

 tices, is limited to a few careful growers. 



Climate and situation. The olive tree in Western Europe thrives in 

 the open air as far north as 46, though beyond 44 it only bears ir- 

 regularly and scantily 5 from that point the size of the tree and the 

 regularity of yield increase as one proceeds farther south until 18 is 

 reached ; beyond that latitude the tree grows luxuriantly, but does not 

 yield fruit. Spain being situated between 35 59' 49" and 43 47' 29" 

 of north latitude, the whole of its territory is within the limits of the 

 olive region. 



Observation has established the fact that the olive in order to mature 

 requires a certain number of units of heat during the period o^ most 

 active vegetative life, said period beginning with the first appearance of 

 the blossoms and ending with the first severe frost. This number of 

 heat units (each of 1 centigrade), which varies with different varieties, 

 and ranges from 3,400 up to 3,978, is to be computed by adding the 

 mean heat of each day during the period between blossoming (which 

 requires a temperature of +19) and the first frost. Any district in 

 which the temperature will sum up to 3,978 during that period is there- 

 fore adapted to olive culture, provided the winter is not severe enough 

 to kill the tree. In that sense the limit of its endurance is a tempera- 

 ure-7 to- 8, which, however, must not last beyond eight continuous 



