OLIFAX - 2

- OLIVE  VARIETY SUITABILITY -

Olive Agencies Information Services

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It is important to choose olive cultivars which will give the  grower the highest possible financial returns. In much of the Mediterranean, local cultivar traditions are extremely well-rooted and few growers choose cultivars not traditionally grown in their region.

Mediterranean growers choose their cultivars according to four main criteria -

1. Disease resistance 2. Regional traditions 3. Final product desired 4. Climate.

One of the most important of these criteria for cultivar selection in the Mediterranean is the prevalence of diseases within a region.  For example, if you are wanting an olive for oil production and you know that  wood borers and peacock spot are rampant in your region, then you may choose other than Frantoio and Pendolino.

The beauty of this for the Australian grower is that olive diseases are very few and are relatively easily controlled through applications of the relevant deterrent. Also local cultivar traditions have not been set within the Australian olive industry. This means that the Australian grower's  are presently going to choose their cultivars according to the latter two  criteria of:- 'Final Product Desired' and 'Climate'

The FINAL PRODUCT  DESIRED is often decided by the demands of local and/or export markets. Initially growers must decide whether they are wanting to produce olives for oil alone, table fruit alone or for both oil and table fruit. The most common dual purpose cultivars in Australia are Manzanillo, Kalamata and Hardy's Mammoth. It should  be noted that Kalamata gives an excellent quality oil however it is rarely  processed for oil due to the high price available on the fresh fruit market. All  three of these cultivars are well suited to pickling and also have oil contents high enough to make commercial oil extraction worthwhile.

In addition, Frantoio (Paragon) olives are primarily for high  class oil but many growers like the nutty flavour of the pickled fruit.

The cultivars such as Frantoio (Paragon), Correggiola and  Nevadillo Blanco contain a high percentage of quality oil and are the most commonly selected for Australian groves specialising in olive oil production. The Spanish Picual and Arbequina are two popular olive oil cultivars soon to be available in Australia.

If the grower decides on table  fruit production then cultivars are chosen by their yield, size of fruit and suitability for commercial processing. Commercial table  fruit processing is most efficient if the cultivar has a flesh-to-pit ratio  greater than 6:1 (ie 6 parts flesh to 1 part pit), and the flesh has a firm texture. If black table olives are the desired product then the grower must also look for a cultivar with a relatively even ripening stage for the majority of the crop. The other (less healthful) option is to process green olives using  sodium hydroxide lye processing to artificially turn the olives black.

Cultivars such as Manzanillo, Hojiblanca, Kalamata, Sevillano, Hardy's Mammoth, UC13A6 and South Australian Verdale are all known for their excellent textures and flavours when processed as table olives. As California  and southern Spain well testify, Manzanillo is ranked as the world's number one table olive. Its cropping ability, disease resistance, texture and flavour combine to place it at the peak of medium sized table olives, and its medium/high oil content also makes it a valuable oil cultivar.

The second and equally important criteria is the CLIMATE in which the grove is to be established. Due to the olive tree's hardiness and adaptability, the majority of cultivars can survive in just about any climate except the tropics and the poles. They have an inbuilt ability to withstand droughts and physical damage which would be the certain death of most other trees. However, it must be noted  that olives will often survive in a harsh climatic zone at the expense of the crop. This is naturally unsuitable for a commercial grove and highlights the importance of climatic suitability of cultivars. From a commercial point of view, where the grower is wanting healthy, low maintenance trees and regular, heavy crops, climate mustn't be overlooked.

The following list divides Australia's most commercially viable  cultivars into three climatic categories based solely around temperature. Although variables such as rainfall  seasons and preferred soil types can effect individual cultivars in different  ways, little is known of these effects under Australian conditions. Some  cultivars will crop well in a range of climates and are listed as such below.  This list is based on both Australian and international research available to date but cannot be considered conclusive as some of the cultivars have not been trialled in all climates.

Cold Climates - Areas where temperatures can fall below - 8ºC and snow may fall occasionally. These regions  generally only grow oil olives as they are less prone to heavy frost damage. A  brief International Olive Oil Council summary of the cold hardiness of olives  follows.

"The olive can withstand low temperatures of -8ºC or -10ºC, and  even lower as long as it is not subjected to them for many hours, thawing  proceeds slowly and the tree is not at the active growing period [September-December in Australia]. During the vegetative stage, the olive tree is sensitive to low temperatures which can cause damage to twigs and secondary  branches, and even to the trunk and scaffold branches. Resistance to cold is a  varietal trait. To ensure it fruits well, the olive does, however, need  temperatures close to zero which induce vegetative rest. It withstands high summer temperatures well, and even lack of ground moisture, although it then adjusts its growing activity to an essential minimum."

The cultivars in Australia most commonly selected for these  cold climates are Frantoio (Paragon), Correggiola, Leccino and Pendulina.  (Californian research has also shown Barouni and Sevillano as quite resistant to  extreme cold).

Moderate Climates - Areas where minimum winter temperatures are generally -3ºC to -4ºC and very rarely go below - 6ºC. Such areas are considered to be typical of the world's olive growing  regions. These areas provide the necessary winter chill requirements for  dormancy without being so cold as to possibly damage any late season  crop.

Most varieties available in Australia are believed to be viable  in such areas. They include Arbequina, Azapa, Barouni, Correggiola, Frantoio (Paragon), Hardy's Mammoth, Hojiblanca, Kalamata, Leccino, Manzanillo, Moraiolo, Nevadillo Blanco, Picual, Sevillano, UC13A6, Verdale, South Australian Verdale  and Wagga Verdale.

Warm Climates - Areas which have an average daily temperature in July of 12 degrees Celsius or less but rarely frost or fall below 0 to -2ºC. Areas warmer than this are generally considered unsuitable or marginal for commercial olive groves as they do not allow the  trees to rest during winter and thereby reduce their ability to flower and set  fruit in Spring.

The cultivars believed to be most suitable for these warm areas  include Azapa, Barouni, Frantoio (Paragon), Kalamata, Manzanillo and UC13A6.  (Nevadillo Blanco is also showing good crops in warm winter areas.)