Olives

Climate change is expected to have a noticeable effect on the areas suitable for olive cultivation and to yields. In the Mediterranean region, temperatures are projected to rise more than the global average, while precipitation is expected to decrease substantially. Changes have already become apparent in some areas. Additional threats to the olive groves are the pests and pathogens which are prevalent in most areas. Most of these can be dealt with to some extent but the increased extreme variation in climatic conditions will make forecasting the development of pests and diseases more difficult. The major existing pest in Greece is the olive fruit fly (bactrocera oleae, common Greek name: δάκος) which is usually treated by spraying with acceptable pesticides and/or by trapping. Another major pathogen which is currently spreading throughout the Mediterranean basin is xylella fastidiosa, a sub-species of which has spread widely in some Italian olive groves and causes olive quick decline syndrome whereby the trees die back and no longer produce olives. Initially the only method of treatment was to clear infected areas but recently non-phytotoxic bactericides have been developed which may limit the more severe effects. This pathogen has not so far been detected in Greece.

Lesvos has been likened to one big olive grove and, with on average over 100 trees per inhabitant, can claim to contain the largest number of olive trees per capita in the world. Cultivation of olive trees goes back thousands of years and the production of olive oil has always been one of the most important economic activities on the island. About 20% of all Greek olive oil comes from Lesvos making it the country’s third most important producer of olive oil after Crete and the Peloponnese.

Most of the oil from Lesvos is produced from the Kolovi variety of olive trees (olea europaea var. pyriformis). This variety is indigenous to Lesvos and is found only in small areas in a few other locations in Greece. It is well-adapted to the limited rainfall on the island. Another variety, Adramytini (olea europaea var med. Subrotunda), also found across the sea in Asia Minor, comprises about 20% of the island’s trees while a small amount of a variety called Throumbolia makes up the remainder of the trees that are cultivated. The oil obtained from the Kolovi olives differs from those of other regions in that it has a low chlorophyll content. It therefore lacks the characteristic green colour of other oils and, since it also has a lower viscosity due to its higher unsaturated fatty acid content, it has in the past been sometimes been considered inferior. However, partly due to its distinctive balanced taste and dedicated efforts to produce consistently high quality products, olive oils from Lesvos have received international recognition as well as many awards.

Although olives and olive oil are the main products of olive tree cultivation, the leaves of the tree also have been used for centuries for their medicinal properties either taken as a tea or as a powder from the dried leaves. Extracts of olive leaves are also available commercially. The main constituents of the leaves are oleuropein and hydroxytyrosol which are polyphenols with antioxidant properties and established health benefits including cholesterol and blood pressure reduction. There is also some support to claims for their use in the management of type 2 diabetes.

The wood from olive trees, apart from being used as a fuel, can be crafted into small household objects such as bowls, cutting boards, and decorative items, and there are also efforts to make use of the pits from olives which, although also used as a low quality heating fuel, are otherwise usually regarded as a waste product of olive oil production.