Page:The Olive Its Culture in Theory and Practice.djvu/45

Rh breeze from the Mediterranean Sea. For successful cultivation the yearly mean temperatures should not be less than 57 degrees Fahrenheit. As to locality where olive culture is possible and practicable. Five hundred and eighty-eight feet of elevation represent one degree of latitude, so Colfax with an elevation of 2421 feet above the level of the sea and standing nearly on the thirty-ninth parallel of latitude must be debited with a little more than four degrees, which would bring it up to between forty three and forty four degrees, showing that Colfax and places of similar elevation and latitude nearly touch the northern limit of the olive in California. To cultivate it successfully further north a lower situation must be sought. Hence the further south the point of cultivation the greater may be the elevation. In the Sierra Nevada mountains, in Grenada, Spain, in latitude thirty-seven degrees, the olive flourishes at a height of three thousand feet. In Algiers, North Africa, in about latitude thirty-five in the Atlas range, it is found at a height of forty-eight hundred feet. In Catania, Italy, it is successfully grown at an elevation of three thousand one hundred feet. The olive dearly loves a breeze, not simply air and ventilation but a veritable soft wind. This is therefore necessary to its well doing, especially at the flowering season. A still, intense heat may be fatal to the promise of a crop by burning off the blossoms; for this reason and also to escape humidity it forsakes the plain and seeks the middle hills. The olive avoids the arid tops of wind swept heights but its home is the half hill. Follow a line of olive trees up a steep and it will be noticeable that those nearest the top are found to be stunted and lacking soil about the roots, the earth having been carried down the slope by rains and the trees are visibly affected by their situation.

Within the olive zone there undoubtedly are many points where the tree will not thrive because it is exposed to too great cold which must be fatal to it—say anything below fourteen degrees—or, if the heat be too great it evaporates the sap and thus prevents nutrition.