Before Harvest

Before harvest, an olive fruit comes as a beautiful bloom olive flower.

Olive (Olea europaea; family Oleaceae): subtropical, broad-leaved, evergreen tree and its edible fruit. 

The tree, ranging in height from 3 to 12 metres (10 to 40 feet) or more, has numerous branches; its leaves, leathery and lance-shaped, are dark green above and silvery on the underside and are paired opposite each other on the twig.  The wood is resistant to decay; if the top dies back, a new trunk will often arise from the roots.  The tree’s beauty has been extolled for thousands of years.  The edible olive was grown on the island of Crete about 3500 bc; the Semitic peoples apparently cultivated it as early as 3000 bc.  Olive oil was prized for anointing the body in Greece during the time of Homer and it was an important crop to the Romans c. 600 bc. Later, olive growing spread to all the countries bordering the Mediterranean.

Olive Fruit

The olive fruit is classed botanically as a drupe, similar to the peach or plum.  Within the stone are one or two seeds.  Olives tend to have maximum oil content (about 20–30 percent of fresh weight) and greatest weight six to eight months after the blossoms appear.  At that stage they are black and will continue to cling to the tree for several weeks.  Fruits for oil extraction are allowed to mature but for processing as food, immature fruits are picked or shaken off the tree. 

Hundreds of named varieties of both types of olives - table and oil  - are grown in warm climates.  In California, olives such as the Mission variety are grown almost exclusively for table use.  In Europe, olives such as the Picual, Nevadillo, and Morcal are grown mostly for oil.

Picking of Olives

Olives are harvested in the autumn and winter. More specifically in the Northern hemisphere, green olives are picked at the end of September to about the middle of November.  Blond olives are picked from the middle of October to the end of November and black olives are collected from the middle of November to the end of January or early February.  In southern Europe, harvesting is done for several weeks in winter, but the time varies in each country and with the season and the genus. 

Most olives today are harvested by shaking the boughs or the whole tree.  The use of olives found lying on the ground can result in poor quality oil.  Another method of harvesting involves standing on a ladder and "milking" the olives into a sack tied around the harvester's waist.  A third method uses a device called an 'oli-net' that wraps around the tree trunk and opens to form an umbrella-like catcher from which workers collect the fruit.  Another method uses an electric tool, the 'oliviera', which has large tongs that spin around quickly, removing fruit from the tree.  Olives harvested by this method are used for oil. 

Table olive varieties are more difficult to harvest, as workers must take care not to damage the fruit; baskets that hang around the worker's neck are used.  In some places in Italy, Croatia and Greece, olives are harvested by hand because the terrain is too mountainous for machines.  As a result, the fruit is not bruised, which leads to a superior final product.  The method also involves sawing off branches, which is healthy for future production.  The amount of oil contained in the fruit differs greatly according to the genus; the pericarp is usually 60–70% oil. Typical yields are 1.5–2.2 kg (3.3–4.9 lb) of oil per tree per year.

Pruning

In mature trees, pruning is mainly required to renew the fruiting surface of the tree and achieve high yields, maintain vegetative growth of fruiting shoots, maintain the skeleton structure, contain tree size, favour light penetration and air circulation inside the canopy, permit control of pests and diseases, prevent aging of the canopy, and eliminate dead wood. Under certain circumstances, pruning can be required to alleviate the effect of abiotic stress, to re-form the canopy after damage by frosts and pests, to rejuvenate old or abandoned trees and to adapt an obsolete training system to mechanical harvesting.  In modern olive growing, the training system should permit easy movement of machinery in the orchard; little attention needs to be paid to specific tree shapes.