Olives (Olea europaea) have been at the centre of civilisation for many thousands of years.
All around the Mediterranean, the wood from olive trees has been used, often to fuel wood-fired ovens or to make sturdy long-lasting furniture. The fruit has been pickled and dried, and the oil has been used in cooking, burnt in lamps for light, and used in lotions for skin conditions since the time of Galen.
Olives in Australia
Olives were introduced to Australia in the late 1700s, shortly after the First Fleet, but then languished until the influx of Italian migrants in the mid 1900s. There are some olive trees that are close to 200 years old in various gardens and parks around Melbourne. In the Banyule Gardens, there are a number of olive trees, the so-called ‘Ligurian’ olives that date back to the 1860s.
In the last 30 years, olive trees along the Murray River have been cultivated for olive oil and pickling. Plantations have been established on the Mornington Peninsula and even as far south as central Tasmania.
Olives thrive in a lime rich soil with a pH of 7 or above and require good drainage. The climate in southern Australia is ideal as olive trees require a warm climate with cold winters, as long as the temperature remains above -10ºC.
It is often seen as a drought-resistant tree but they still require adequate water at flowering and fruit set to ensure good crops. If they are not irrigated, they tend to form a biennial cropping pattern.
The soil must be well drained and calcareous. Olives have shallow root systems and do not tolerate waterlogged soil. It is a good idea to rip or deeply hoe the soil, then plant the tree on a small mound or delve. Ensure that there are no weeds to compete with the trees, particularly for the first four to five years as the tree is establishing itself.
Olive trees need to be regularly fertilised in autumn and in spring. Well rotted chicken or cow manure is ideal. Spread this around the base twice a year.
Pruning and pests
Olive trees fruit best in an open vase shape and should be pruned accordingly. Leave three to four branches and always remove any water shoots on the inside and any suckers at the base.
They say that you prune the tree to allow a bird to fly though! If you keep too much foliage, it’s prone to diseases such as black sooty mould or olive scale. This is transported by ants and is controlled by using winter oil in December and in March or April.
The other pest is peacock spot – a fungal condition that produces pale leaves with a ‘bull’s eye’ on the leaf. The leaves eventually drop off, producing poor fruit set and poor fruit in general. This is controlled with a copper spray in late spring and as soon as it appears on the leaves.
Selecting the right variety
There are probably over 100 varieties of olives coming from different parts of the Mediterranean. These varieties tend to require slightly specialised conditions, extra heat for example, or they are slightly intolerant of extra water and can be a little temperamental. Diggers make selection easy, with all their olive varieties thriving in Australian conditions when properly cultivated.