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Olives
— Production guideline —
agriculture,
forestry & fisheries
Department:
Agriculture, Forestry and Fisheries
REPUBLIC OF SOUTH AFRICA
Olives
— Production guideline —
March 2010
Department of Agriculture, Forestry and Fisheries
2010
Printed and published by
Department of Agriculture, Forestry and Fisheries
Compiled by
Directorate Plant Production in collaboration with the ARC
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Obtainable from
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PRETORIA
0001
CONTENT
General .................................................................................................
1
Cultivation practices .............................................................................
8
Post-havest handling ............................................................................ 18
Production schedule ............................................................................. 18
Utilisation .............................................................................................. 19
References ........................................................................................... 22
Personal communication ...................................................................... 23
Notes .................................................................................................... 24
GENERAL
Scientific name: Scientific name: Olea europeae L.
Common names: Olive (English), Olyf (Afrikaans), Umnquma (isiXhosa)
The type of olive tree which produces edible olives and olive oil, belong
sto the family Oleaceae and is classified as Olea europeae L. The genus
Olea includes approximately 30 other species of which only the species
Europeae bears edible fruit from which oil can be extracted. Some of these
olivewood (Olea europeae subspecies africana), ironwood (Olea capensis), dune olive (Olea exasperata) and forest olive (Olea woodiana).
Origin and distribution
Olives were sacred to Athena, the ancient Greek goddess of peace and
wis dom (Anon, 2006a). According to folklore, Athena and Poseidon
(ancient Greek god of the sea) had a dispute on whose name should be
given to a new city in Greece. In order to resolve the matter, they agreed
to name the city after the person who offered the most precious gift to the
citizens. Poseidon then struck a rock with his sceptre and produced salt
water, hence the sea. Athena on the other hand, drove her spear into the
soil and it turned into an olive tree. Athena’s gift was regarded as being
more beneficial to the citizens and the city was therefore named Athens in
honour of Athena (Anon, 2006b).
According to Anon (2006a) the olive is also an emblem of:
Virtue—Greek newly-married brides wore an olive-garland in stead of the
usual orange-blossom one;
Productivity—Olive trees bear large numbers of fruit and are therefore
regarded as valuable to their owners;
Merit—A crown of olive twigs was the highest honour which could be bestowed on a citizen of ancient Greece;
Peace—An olive branch was a symbol of peace in ancient times. If a
person presents an olive twig, it can be regarded as a gesture of peace;
Prosperity—King David states in Psalm 52:8 ‘But I am like an olive tree in
the house of God’ (Anon, 2006a);
Victory—A wreath made of olive leaves was used to crown the athletes in
the ancient Olympic Games. The Greeks continued this tradition during
the 2004 Summer Olympics (Anon, 2006c).
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Homer, an ancient Greek poet, singer and composer of the legendary
Odyssey and who lived between 800 and 700 BC, called olive oil ‘liquid
gold’ (Anon, 2006b). According to him the olive tree has been thriving
in Greece for more than 10 000 years. Plinius Secundus (79 BC to 23
BC), an ancient Roman author, cited a sacred Greek olive tree that was
1 600 years old. However, in Genesis 8:11 it states that ‘When the dove
returned to him in the evening, there in its beak was a freshly plucked olive
leaf. Then Noah knew that the water has receded from the earth’ (Anon,
2006a). Olive trees were also mentioned in the Bible as to have grown in
the Garden of Gethsemane during the times of Jesus (Anon, 2006d).
According to Anon (2006d and references within), olive trees are native to
the Mediterranean and wild olives were harvested by Neolithic peoples as
early as 8 000 BC and processed into oil by 4 500 BC in the country that is
currently known as Israel. Olive stones were found in archaeological sites
dating as far back as 9 000 BC, however, there is clear evidence of domestication of olive trees in the Mediterranean region from approximately
3 500 BC (Anon, 2006e).
Modern olive cultivars descend from multiple wild ancestors, however, the
detailed history of domestication is not known yet (Anon, 2006d and references within).
Olives were introduced to South Africa by Jan van Riebeeck, the first
Governor of what was then known as a Dutch settlement. The first reference to olives was on 6 August 1659 when he recorded in his diary: ’The
season is also approaching for planting and grafting the olive and all kinds
of home and Indian fruit trees…’ (Karsten, 1955).
The current olive industry was established by an innovative Italian nurseryman, Ferdinando Costa, who arrived in South Africa in 1903. The vigorous
growth of the indigenous wild olives (Olea europeae subspecies africana)
on the slopes of Table Mountain made him realise the potential of growing
the European olive in South Africa. He therefore imported known cultivars
from Italy and started propagating trees by using the indigenous wild olive
seedlings as rootstocks. Ferdinando bought a farm at Paarl in the Western
Cape Province and erected an oil-processing plant. He also encouraged
other farmers in the region to cultivate olives. The greater part of the olive
industry is still based within the Paarl Valley in the Western Cape Province.
However, olives are also grown in certain summer rainfall regions of the
country.
2
Production levels and areas
South Africa
According to Mr Andries Rabie (2007), Chairperson of the South African
Olive Growers’ Association, the total estimated olive production within the
Republic of South Africa for 2006 is as follows:
Olive production in South Africa
Type
Quantity
Table olives (fruit)
Olives for processing into oil
Olive oil
2 000 to 2 500 metric ton
3 000 to 3 500 metric ton
600 000 to 650 000 kg
Internationally
South Africa‘s contribution is insignificantly small in comparison to the top
three producers, namely Italy, Spain, and Greece.
The major international olive producers (FAO, 2006) for 2005 were as
follows:
Major international olive producers (FAO, 2006) for 2005
Rank
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Country
Italy
Spain
Greece
Turkey
Tunisia
Syrian Arab Republic
Morocco
Egypt
Portugal
Lebanon
Libyan Arab Jamahiriya
Algeria
Palestine
United States of America
Argentina
Jordan
Israel
Peru
Islamic Republic of Iran
Croatia
Production
(Metric ton)
4 114 293
3 712 700
2 200 000
850 000
700 000
620 000
450 000
310 000
270 000
180 000
180 000
170 000
140 000
113 400
103 000
73 990
50 000
43 000
41 000
33 000
Income
(international $ 1 000)
2 058 257
1 857 352
1 100 594
425 230
350 189
310 167
225 122
155 084
135 073
90 049
90 049
85 046
70 038
56 731
51 528
37 015
25 014
21 512
20 511
16 509
3
Botswana
Mozam
b
Namibia
ique
Zimbabwe
Pretoria
Swaziland
Upington
Kimberley
Lesotho
Prieska
Durban
Sout Africa
Beaufort West
Graaf Reinett
Cape Town
Paarl
Stellenbosch
East London
George
Port Elizabeth
Major production areas in South Africa
Although olives are established throughout the Republic of South Africa,
the olive industry is centred around Paarl and Wellington in the Western
Cape Province. This area recently expanded to include the RiebeekKasteel, McGregor and Hermanus farming districts. A number of orchards
have successfully been established in other regions of the country, viz.
Western Cape Province (Prince Albert, Oudtshoorn, Beaufort West and
Laingsburg), Northern Cape Province (Vaalharts, Prieska and Upington),
Eastern Cape Province (Alicedale), North West Province (Brits) and
Limpopo Province (Modimolle).
Both the production and local consumption are currently growing. However, table olives and olive oil are still imported into the Republic of South
Africa as the current demand exceeds the local production. The current
state of affairs can change as the South African producers are known for
producing crops of the highest quality and can compete with larger producers in foreign countries. The olive industry has the potential to grow and
export to foreign markets.
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Description of the plant
Roots
The root system is generally shallow and widespread. Approximately 80 %
of the roots occur within the top 60 cm of soil. The soil characteristics will
determine the depth of the root system.
Stem
The different cultivars vary in their growth habitat. Young shoots are soft
and flexible yet strong, while the older stems as well as the trunk of the tree
are very hard. The tree has numerous branches which bend down as they
mature, giving the tree a bushy appearance. Shoot growth mainly occurs
in two flushes, i.e. the primary flush during spring, followed by a secondary flush during autumn. Olive trees have two kinds of shoots. Shoots are
either vegetative (woody) or reproductive (bearers with little or no terminal
elongation). No fruit will be borne on the vegetative shoots while all the fruit
will be borne on the reproductive shoots.
Leaves
The leaves are lance shaped and are arranged alternatively on opposite
sides of the shoots. The upper leaf surfaces usually have a dark green
colour while the undersides are silvery-grey. The silvery-grey colour can
be ascribed to the presence of tiny, umbrella-shaped hairs also called
trichomes. These trichomes cover the stomata of the leaf. The presence
of these trichomes as well as a thick cuticle protects the plant from water
losses. Leaves have a lifespan of 2 to 3 years, after which they turn yellow
and drop from the tree. Their photosynthetic activities and storage functions are taken over by the younger leaves.
Flower
Daylength is not important in stimulating the development of flowers.
However, olives need optimum chilling temperatures for flower development. The initiation of flower buds already starts during the summer.
Flower development is stimulated by lower temperatures during the early
winter months, slightly higher temperatures during the middle of winter
(average minimum of 13 °C) and higher temperatures towards the end of
winter. Flower differentiation takes place in the lateral buds. These buds
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eventually develop into flower clusters. Each flower cluster has between
10 to 12 individual flowers. In the Western Cape Province the flowers
bloom during the last part of October. The petals of the flowers will be shed
within 1 day after blossoming. The flowers will then be either ‘perfect’ or
‘imperfect’ flowers. The perfect flowers have two stamens (male reproductive organs) and a pistil (female reproductive organ) while the imperfect
flowers have two stamens and an undeveloped pistil. Imperfect flowers
can therefore bear pollen but would not be able to bear fruit. A heavy crop
load will be achieved if only 1 % of the all the fruit sets. Olive trees are wind
pollinated. Cross-pollination was found to be beneficial to fruit set.
Fruit
Olive fruit mature normally between 4 to 6 months after blossoming.
However, fruit maturation will also be influenced by the kind of cultivar,
weather conditions and specific cultural practices. The first 42 days after
full bloom is a critical period during which active vegetal growth takes
place. Flowers which were not fertilised, will also abort during this period
and the remaining fruit will start to develop. Fruit is usually harvested at 4
to 6 months after flowering. The fruit changes colour as it ripens, i.e. from
green to straw-yellow and eventually to dark red or black. Olives should
not be harvested too late in the season as this will have a negative effect
on the following year’s production. Olive trees tend to bear heavy crops
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followed by light crops in alternate years. This phenomenon is called alternate bearing.
Cultivars
The following aspects should be taken into account in determining which
cultivar to establish:
• Market demand (table olives vs oil production)
• Adaptability of cultivar to the specific farming area
• Pollination requirements
• Availability of planting material
• Scheduling harvesting of olives with harvesting times of other crops on
the farm.
Recommended cultivars
Mission—black table olive and olive oil
Kalamata—black table olive
Manzanilla—green table olive
Barouni—green queen table olive
Frantoio—high-quality olive oil and cross-pollinator
Climatic requirements
Temperature
The production of olives under harsh, unfavourable conditions will not be
economically viable, although olives are known to survive under these conditions. Olives are traditionally grown in regions which have relatively cool,
frost-free winters followed by hot, dry summers. Olive trees are less sensitive to wind damage than other types of fruit. However, wind-damaged
fruit will not be suitable as table olives and would only be suitable for the
production of oil. It is, therefore, important to select the specific cultivar in
accordance with the prevailing weather conditions of an area.
Rainfall
An annual rainfall of between 650 and 900 mm would be required for dryland production.
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Soil requirements
Olives can be grown on marginal soils. However, the growth and production will not be optimal. Olives therefore require well-drained and wellaerated soil. The soil should be prepared to a depth of at least 80 cm. It
is important to have the soil analysed before planting in order to obtain
guidelines for soil preparation.
Poor production of olives will be obtained on shallow soils. Trees cultivated
on wet or waterlogged soils are susceptible to plant diseases. Water uptake will be restricted in wet soil owing to low oxygen levels in the soil. Very
sandy soils have poor water-holding capacities and will therefore require
careful management in terms of irrigation and nutrition. Soils with a clay
content of above 30 % are unsuitable for olive production while soils with
a high gravel content are ideal. The pH (KCl) level of the soil should be
above 5,0, preferably close to 6,0. However, a moderate harvest could still
be obtained with lower or higher soil pH levels. Olives are more resistant
to saline conditions in comparison to stone fruit but far less tolerant than
dates. Nitrogen (N), potassium (K) and boron (B) are the most important
nutrients for olive trees. A soil analysis will determine how much fertiliser
should be applied to ensure optimum production.
CULTIVATION PRACTICES
Propagation
Olive trees can be propagated by using several methods such as grafting
of young wood on seedlings of cloned rootstocks or by the rooting of hardwood, semihardwood or softwood cuttings. The method used, will depend
on the cultivar, facilities that are available as well as the expertise of the
grafter.
The propagation of hardwood cuttings is a traditional method used in the
Mediterranean countries and it requires low capital input and minimal infrastructure. However, it is not advisable to use hardwood cuttings as the risk
of infections by pests and diseases is increased by the utilisation of older
wood. Semihardwood cuttings, which are dipped in synthetic plant growth
regulants, are most often used. The only disadvantage of this method is
that the cuttings should be kept under controlled environmental conditions
such as a high humidity glasshouse. However, such a facility is very expensive to erect.
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It is, therefore, advisable to order trees from a reputable nursery that is
registered with the South African Olive Growers’ Association (SAOGA). It
is also important to ensure that the following criteria are met before olive
trees are purchased. The trees should:
• be true to type
• be free of pests and diseases
• not have any signs of nutrient deficiency
• have a well-developed root system
• have one main straight stem with some secondary lateral branches
sprouting from approximately 20 to 30 cm above the soil surface
• be 18 months old
• have a height of approximately 0,5 m.
Soil preparation
An olive tree has a lifespan of at least 30 years. It is, therefore, important
to select the correct locality and to prepare the soil properly. It is beneficial
to seek expert advice with regard to site selection and soil preparation. Soil
samples should be taken prior to soil preparation in order to determine the
water-holding capacity as well as the nutrient content of the soil.
At least five soil sample holes should be made in a plot of 1 ha (100 m x
100 m). A spade should be used to make a hole of 1 m wide, 1 m in length
and 1 m deep. A vertical sod on the side of the hole to a depth of 30 cm
must be taken and transferred into a marked plastic bag. The second sample should be taken on the side of the hole in the bottom part of the profile
(30 to 60 cm deep). The blade length of a new spade is approximately 30
cm.
Any layers in the soil, such as a stone or clay layer as well as the depth at
which it occurs should be recorded. All stones larger than 10 cm in diameter may be removed from the sample. However, the number and sizes
of stones not included in the sample should be recorded. The samples
can be sent to a reputable institution where the soils will be analysed. The
sampling hole should be filled again. The bottom layer soil, in other words
the layer that was removed last, should be replaced first into the hole. This
step is important as the bottom layer usually consists of more clay. If the
bottom layer of soil is replaced into the top part of the hole, it can lead to
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soil compaction. The samples taken at the different holes should not be
mixed or added together. This is important as the soils, within one plot
can differ in texture. The positions within the plot where the samples were
taken, should be marked.
The results of the soil analysis will indicate whether the soil is suitable for
olive cultivation and, if so, which kind of fertilisers as well as the quantity
of fertiliser has to be applied. Perennial weeds should be removed before
soil preparation. Soils should be assessed for the presence of harmful
nematodes or soil pathogens, especially if the soils have previously been
planted with other types of crops such as vines. The soil should be fumigated if necessary. However, it is important to seek expert advice with
regard to soil fumigation. Aspects such as the availability of water and
drainage should also be considered. Soil preparation is usually done on a
large scale by professional contractors. Planting holes, 1 m wide, 1 m in
length and 80 cm deep (1 x 1 x 80 cm), should be made on plots which are
too steep to be prepared by implements or on plots which are too small for
the movement of large implements. Specific quantities of lime, phosphorus, potassium and microelements, based on the soil analysis, should be
applied to the soil during soil preparation. The edges of the planting holes
should be roughenedto allow the plant roots to penetrate the soil adjoining
the planting hole. The hole should be filled again as described previously
and marked clearly. Soil preparation should be done during the month of
May.
Planting
There are certain aspects that should be taken into account, such as slope
of the plot, planting density, planting date and planting depth.
Slope
The steeper the terrain, the more expensive orchard management be comes for the producer.
PLANTING DENSITY/SPACING
Planting distances will depend on cultivar, soil fertility, level of orchard
management, availability of water and the size of the orchard. Trees are
traditionally spaced 7 m apart within the planting row while the rows are
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spaced 7 m apart, resulting in a planting density of 200 trees per hectare.
Modern orchards are planted at a higher density with the rows spaced 6
to 7 m apart while the plants are spaced 3 to 5 m apart within the planting
row. Cultivars such as Manzanilla should be spaced more closely, while
strong growers, such as Mission, would be spaced further apart.
Planting date
The trees should be planted during late winter or early spring.
Planting depth
Trees which are obtained from a nursery would usually be supplied in
plastic bags. A square-shaped planting hole should be made in the middle of the previously prepared hole (see soil preparation). This planting
hole should not be deeper than the original length of the plastic bag. The
roots should not be disturbed during planting. The plastic bags should be
removed carefully before planting, taking care not to damage the roots or
allow the roots to dry out. The roots should not come in contact with any
fertiliser or manure which was applied into the planting hole as it could
result in scorching. The soil should then be packed firmly around the roots
and irrigated directly after planting. The trees should be supported with
sturdy bamboo of wooden stakes and tied with decomposable twine in
order to ensure upright growth and to prevent wind damage. The stems of
the trees can be protected for the first couple of years by painting it with
whitewash or white PVA paint.
Fertilisation
Olives, similar to other fruit trees, require macronutrients such as nitrogen
(N), potassium (K), phosphorus (P), calcium (Ca) and magnesium (Mg).
Trace elements such as boron (B), zinc (Zn), iron (Fe), copper (Cu),
manganese (Mn) and molybdenum (Mo), are only required in small quantities. Application rates of fertilisers should be done in according to the
results of proper leaf and soil analyses. Nitrogen applications should be
managed carefully as it is critical to maintain a balance between vegetal
growth and yield. Small quantities of nitrogen should be applied regularly
to prevent excessive vegetal growth caused by single large applications.
Foliar applications (sprays) could be beneficial under very dry conditions,
or in the case of nutrient deficiencies, but are generally not recommended.
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Potassium is usually applied directly after planting followed by applications
during every spring and autumn. It is critical to restore the K levels in the
shoots before the start of flower initiation as it will reduce the tendency of
alternate bearing. Phosphorus does not leach from the soil. The phosphorus that was applied during soil preparation would therefore be sufficient
for several years. The pH levels have to be rectified only when necessary
and in accordance with a soil analysis.
Method(s) and time of application
NITROGEN
This element is utilised by the trees throughout the growing season and
should be applied three times per year, i.e. at the beginning of August
when the trees start growing, just before bloom (early October) and in
autumn (mid March). Two types of fertilisers can be used, viz. ammonium
sulphate [(NH4)2SO4] or limestone ammonium nitrate (LAN). The quantity
of nitrogen that should be applied, will depend on the production potential,
for instance if a production of 2 t/ha is envisaged, the nitrogen fertiliser application rate would be 15 kg/ha. However, young trees should be fertilised
differently. During the first year, 20 g of LAN or 30 g of (NH4)2SO4 (for more
alkaline soils with a pH (KCl) of above 7) should be applied per tree per
month throughout the growing season. The quantity of fertiliser should be
increased during years 2 and 3 with 40 g LAN or 60 g of (NH4)2SO4 per
tree per month throughout the growing season. From the fourth year after
establishment, 60 g of LAN or 90 g of (NH4)2SO4 should be applied per tree
per month throughout the growing season.
POTASSIUM
Potassium in the form of potassium chloride (KCl) should be applied during
late winter or early spring (70 % of the recommended quantity) and during
autumn (30 % of the recommended quantity). The quantity of potassium
which should be applied should be based on the production and leaf as
well as soil analyses. It is therefore important to seek expert advice.
BORON
This is the only trace element which appears to have a marked influence on
olive production. Boron is necessary for the growth of pollen-tubes, which
is important to ensure successful pollination and subsequent fruit develop-
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ment. Boron, in the form of Borax (sodium borate, Na2B4O7.10H2O), which
contains 11,3 % boron, can be applied to the soil at a rate of 200 g per tree.
It could also be applied as a foliar spray using Solubor, which contains
20,8 % boron. The foliar sprays should be applied during the spring, at
an application rate of 1,5 l/ha. Boron should only be applied if the boron
levels of the soil decrease to less than 2 mg/kg. Foliar application of boron
is highly effective when it is applied during spring, just before flowering.
Other trace elements can be applied according to leaf and soil analyses.
The fertiliser programme should be amended when fungicides are used
which contain copper, manganese or zinc.
Irrigation
Irrigation is a prerequisite for a regular production of high-quality fruit.
Dryland olive production under South African conditions is generally not
recommended. The irrigation requirements of a tree, i.e. the volume of water applied at a specific time and the frequency of irrigation are influenced
by the following factors, viz. the age and size of the trees, the season and
growth stage, the crop size, rainfall, temperature, relative humidity, wind,
soil texture, soil structure, soil depth as well as the type of irrigation system
that is used. A physical analysis of the soil to determine the water-holding
capacity of the soil will assist in ensuring efficient water usage. A good
general rule to use is to wet the soil to the full rooting depth. A young olive
tree requires 15 to 20 litres of water per week during the first growing
season. The volume and frequency of irrigation from the second year after
planting and for mature olive trees will depend on the climate, season as
well as tree size and age. It is therefore important to seek expert advice on
irrigation scheduling.
Weed control
Weed control should start before planting. Repeated ploughing or disking of the infested area during the summer months prior to planting, will
eradicate the weeds. Weeds growing in the root zone of the olive tree
compete with the tree for available moisture, nutrients and oxygen in the
soil. Weed control should therefore be done on a regular basis by either
removing the weeds mechanically or by applying herbicides. A strip of 1
m wide on both sides of the olive trees, within the planting row, should be
cleared of weeds. The weeds in the working row should remain, however,
these should be kept short. The presence of the weeds and other natural
13
vegetation in the working row has certain advantages. It will prevent soil
compaction, reduce soil erosion, will enhance water infiltration and it
harbours beneficial insects and other biological control agents which are
necessary in the orchards.
Care should be taken when using herbicides. It is necessary to ensure that
the specific herbicide is registered for use in olive orchards in the Republic
of South Africa. Fluasifop is the only herbicide which will not cause any
damage to the olive tree. Glyphosate (e.g. Roundup) and thiazopyr (Visor)
can only be used if the herbicide does not come into contact with the
leaves, suckers or the trunk of the tree.
In an organic farming system a relatively thick layer of mulch could be
placed within the tree row to control weeds. This mulch will assist in suppressing weed growth. and it will also stimulate the olive tree to develop
tiny, secondary roots, which is beneficial for nutrient uptake.
Pest control
Olive pests can be controlled primarily by their natural enemies. The use
of pesticides would consequently be unnecessary and provides the opportunity to farmers to grow olives organically. Farmers should be careful
not to disturb the delicate balance between predator and prey by the
unnecessary use of pesticides. Other orchard practices, such as pruning
correctly and minimising the dust raised by orchard traffic, can reduce pest
infestation.
The main pests which occur on olives grown in tSouth Africa are yellow
and black-striped olive beetles, olive lacebugs and olive flies.
Olive beetle
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Olive lace bug
Olive fly
• Yellow and black-striped olive beetles—the larvae of this beetle feed
and tunnel into leaves of especially young trees, thereby inhibiting plant
growth.
• Olive lacebugs—these bugs suck the sap from the leaves, especially in
the case of trees which have a dense canopy. The damage to the leaves
is usually visible as tiny yellow spots on the leaves. These leaves will
turn chlorotic (lose the normal green colouration) and will die eventually
• The olive fly—The adult female insect stings the fruit on the outside and
lays her eggs inside. The eggs later hatch and develop into larvae. The
latter destroy the fruit from the inside as they tunnel into the flesh.
Minor pests which occur on olives in South Africa include:
• Scale insects—such as Ross scale, black scale and oleander scale.
Infestations can occur under dusty conditions.
• Olive psylla—this is a small sucking insect which is related to aphids. It
becomes a serious pest when the ecological balance is disturbed.
• Olive mites—this insect causes leaf deformation, floral damage and bud
drop.
• Mediterranean fruitflies—they leave unsightly marks on fruit, making the
fruit unsuitable for processing
• Seed wasps—these wasps occur only occasionally on domesticated
olive trees. They damage the fruit by burrowing from within the fruit, leaving a small exit hole on the skin of the fruit. The fruit will consequently
only be suitable for oil production.
• Leaf-rollers—the larvae of these insects feed on young leaves and the
shoot tips.
• Stem borers—the damage caused by these insects will be visible as the
individual shoots die back suddenly.
• Termites—these insects chew the leaves and twigs on newly planted
trees.
Nematodes
The olive trees are attacked by the same nematodes which parasitise on
grapevines. Olive trees should therefore not be planted directly in soils
which have previously been planted to grapevines. It is advisable to seek
15
professional advice in order to determine whether fumigation of the soils
would be necessary.
Disease control
There are two main fungal diseases which occur in olive orchards:
• Anthracnose—this disease causes major production losses as the fruit
is mainly attacked. The first infections will be visible as small, reddishbrown spots which will appear on the flower clusters. The infected
flowers will die before they are able to open. Small, circular, depressed,
brown-coloured spots will appear on ripe and partially ripe fruit. The
damaged fruit will not be suitable for processing.
• Olive leafspot—this disease will occur in orchards with restricted air
movement because of densely spaced trees. The first symptom of this
disease is the appearance of faint, dirty spots on the upper and lower
leaf surfaces. The leaves will eventually turn yellow, resulting in leafdrop and death of shoots.
Olive trees are also susceptible to soil-borne root diseases. The trees are
usually infected as a result of poor irrigation scheduling. Continual rainfall
for several consecutive weeks will promote the rapid spread of a fungal
disease. It would be very difficult to control fungal infections under these
adverse conditions. Appropriate orchard management practices and the
application of suitable fungicides can control the diseases mentioned.
However, it is important to follow the instructions carefully, which usually
accompany the fungicide.
Other cultivation practices
Pruning and training
The lifespan of an olive orchard will be determined by the pruning strategy
that is followed. Pruning should be kept to a minimum during the first few
years. Only those branches which are obstructing the growth of other
branches or which grow near the soil surface should be removed.
There are different approaches to the pruning and training of mature olive
trees. In a more extensive type of pruning and training system, three to six
main scaffold branches are selected, which will eventually be shaped into
a semiopen vase. All the upright growth in the centre of the tree should be
16
removed to improve light penetration throughout the tree. However, care
should be taken not to expose the scaffold branches to too much sunlight
as the risk of sunburn will be increased.
The more intensive pruning and training system is quite different, as a
single leader shoot is selected. This shoot is then supported by a stake and
trained upright. Lateral branching is encouraged over the entire length of
the leader from a height of about 40 cm above the soil surface, upwards.
The bottom branches of the tree should be allowed to thrive in order to
obtain a conically shaped tree. Lateral branches should have a diameter of
less than a third of that of the main leader. These lateral branches should
be kept at a somewhat flat angle. Vertically growing smaller branches,
which sprout from the lateral branches, should be removed regularly.
Mulching
It would be beneficial to apply organic mulches such as kraal manure or
decomposed wood sawdust, as it would:
•
•
•
•
•
reduce water loss from the soil
protect the soil from compaction
protect the soil against extreme temperature changes
provide a habitat for earthworms
suppress weed growth.
Harvesting
This is the most expensive operation in commercial olive production and
can represent about 40 % of the total cost involved in producing olives.
Table olives should be picked by hand. Fruit should be picked individually
and placed carefully into picking bags or buckets which have been lined
with foam rubber. Care should be taken not to damage the fruit during picking. Olives which will be used to produce oil are usually removed (stripped)
from the trees onto nets that are positioned underneath the trees. Olives
are usually harvested from February to July. However, the harvesting date
will depend on the specific cultivar and intended processing method. Fruit
which is intended to be processed green, should be harvested when the
colour has changed from a bright green to yellowish-green or when the
first fruit on the tree shows a light pink or purple blush. Only fruit with the
specific size, which are required by the processor, should be harvested.
The rest of the fruit should be harvested at a later stage.
17
Fruit which is intended for processing as ripe black olives should be picked
when having a completely black colour, but before softening or becoming
overripe.
Olives harvested for oil production should be harvested when most of the
fruit on the trees is ripe. The oil content within the fruit increases as the
fruit colours and ripens and then remains relatively constant. Delaying the
harvest until all of the fruit on the tree is ripe will only result in oil of a lower
quality.
It is always a good idea to familiarise oneself well in advance with the fruit
quality requirements of the company which will process the fruit.
POST-HARVEST HANDLING
Olives should be transported to the packing-shed as soon as possible after
harvesting. The containers and crates used for transporting table olives
should be smaller than those used for deciduous fruit and be lined with
foam rubber to minimise fruit damage. The fruit should then be graded
according to size. Any stalks, leaves, malformed, bruised, infested and
overripe fruit should be removed. Olives are extremely delicate fruit and
decay rapidly when bruised, which would make them unacceptable for
processing. Damaged fruit should therefore be processed within 24 hours
after harvesting to ensure good-quality oil. Undamaged fruit could be coolstored for a limited period at a temperature of 10 °C.
The harvested fruit can either be delivered to a commercial processor for
processing or it could be processed at home, but on a smaller scale. Many
olive producers prefer to deliver the harvested fruit to processors as a large
amount of capital is needed to erect a processing plant.
Soil sampling
Soil preparation
Planting
18
December
November
October
September
August
July
June
May
April
March
February
Activities
January
PRODUCTION SCHEDULES
December
November
October
September
August
July
June
May
April
March
February
January
Activities
Fertilisation
Nitrogen
Potassium
Boron
Lime
Irrigation
Pest control
Disease control
Weed control
Pruning
Leaf sampling
Harvesting
Marketing
UTILISATI
UTIL
ISATION
ON
Olive oil is unique compared to other culinary oils in that neither refining
nor the addition of any kind of chemical is necessary to obtain the oil.
The oil can also be consumed immediately after extraction. The oil is an
excellent salad dressing and is ideal for frying and baking. Table olives are
usually served as a snack or in salads and pizzas.
Many of the health benefits attributed to olive oil are supported by various
research findings. The South African consumer has to be educated on the
health benefits of olives and olive oil. They should also be knowledgeable
about olives in order to distinguish between good-quality, locally produced
table olives and olive oil and those inexpensive, third-rate products which
are usually imported. According to the standards of the International Olive
Oil Council (Anon, 2007g), the labels on the olive oil containers should
clearly indicate the grade of the oil:
19
• Extra-virgin olive oil—this oil is obtained from the first pressing of the
olives through the cold pressing process and acidity is less than 0,8 %.
This oil has a superior taste. There can be no refined oil in extra-virgin
olive oil.
• Virgin olive oil—It is made from olives that are slightly riper than those
used for extra-virgin oil and is produced in exactly the same manner.
This oil is judged to have a good taste and acidity is less than 2 %.
There can be no refined oil in virgin olive oil. Virgin olive oil is essentially
defective extra-virgin oil.
• Olive-pomace oil is a blend of refined pomace olive oil and possibly
some virgin oil. Pomace is the pulpy mass that remains after the olives
have been crushed and pressed to extract oil. Although olive-pomice oil
is fit for consumption it may not be called olive oil.
• Lampante oil is olive oil that is not used for consumption; lampante
comes from olive oil’s ancient use as fuel in oil-burning lamps. Lampante
oil is mostly used in the industrial market.
Processing of table olives
Olives cannot be consumed fresh and have to be processed. The strong,
bitter taste of olives can be ascribed to the glucoside compound called
oleuropein. Although this substance is harmless, it should be removed
from the fruit in order to improve the taste of the olives.
There are several methods that can be used to process the olives, such
as the Spanish Green Pickling process, the Greek Natural Black process,
the Kalamata process, the American Canning process and the Greek DrySalted Olives (Costa, 1998).
According to Anon (2007h), a long, slow, natural fermentation process in
brine would ensure a better quality olive as it would retain its taste. Green
olives should be washed in a strong solution of water and sodium hydroxide or potassium hydroxide, before being placed in the brine solution.
Black olives, on the other hand, should only be rinsed in clean water before
being placed in the brine solution. This process of fermentation could take
up to 9 months and should therefore be monitored regularly. There are
other, easier and quicker methods that could be used at home. However,
the taste of the olives might be affected and flavourings such as vinegar,
garlic and herbs could be added to enhance the flavour of the olives.
20
According to Anon (2007h), there are certain aspects that should be kept
in mind before the actual processing can commence:
• Some olive cultivars should be processed when still green, such as
Manzanilla, while other cultivars such as Kalamata and Mission are best
processed when black.
• Only healthy, newly picked fruit must be used. If the fruit has to be stored,
it is important to ensure that it is stored in clean, cool, dry, well-ventilated
crates after harvesting. The fruit must be still be firm and not shrivelled.
• The fruit should be handled carefully in order to prevent bruising.
• The work area should be hygienic. All the equipment (buckets, spoons
etc.) should be clean. High-quality, chlorine-free water should be used.
Black olives
• Wash the olives to remove dust and dirt.
• Place the olives in an airtight container (stainless steel, glass or highgrade plastic containers) and cover completely with fresh water.
• Change the water twice a day (once in the morning and once at nighttime) for a minimum period of 4 to 6 weeks.
• Prepare a brine solution:
– 750 g to 1 kg salt
– 10 l of water
– Wine vinegar to taste (± 1 liter)
21
• Cover the olives with the brine in an airtight container and allow to cure
for at least 4 months.
• Bottling: Place olives into glass jars and cover with hot brine:
–
–
–
–
20 g salt mixed into 1 l boiling water.
Add a film of good-quality extra-virgin olive oil on top of the brine.
Cover immediately with the lid and leave to cool.
Store in a cool place and refrigerate after opening.
• Sprigs of fresh herbs such as rosemary or thyme; or a few cloves or
garlic; or lemon slices could be added before closing the lid.
REFERENCES
ANON, 2006a. Olive. Http://www.websters-on-line-dictionary.org/ definitions/olive, 04/01/2007, 09:15.
ANON, 2006b. Olive oil history. http://www.olympia-oliveoil/oliveoil_history/,
30/10/2006, 10:00.
ANON, 2006c. Ola’s olives—Olive trivia. http://www.olasolives.com/trivia.
html, 30/10/2006,11:00.
ANON, 2006d. History of olives. http://en.wikipedia.org/wiki/Olive_oil History
08/01/2007, 08:15.
A NON , 2006e. Olea europaea (Olive). Iziko museums of Cape Town.
http://www.museums.org.za/bio/plnats/oleaceae/olea_europaea.htm,
31/10/2006, 10:45
ANON, 2007f. Online Bible. http://bibleresources.com, 10/01/2007, 07:45.
ANON, 2007g. Olive oil. http://en.wikipedia.org/wiki/Olive_oil, 23/03/2007,
14:15.
A NON , 2007. Processing table olives. Olives South Africa. http://www.
olivessouthafrica.com/site_files/index.asp, 23/03/2007, 15:30.
B EUKES , O. 1999. Irrigation training manual for deciduous fruit. ARC
Infruitec-Nietvoorbij, Stellenbosh.
COSTA, C. 1998, Olive production in South Africa. A handbook for olive
growers. ARC Infruitec-Nietvoorbij, Stellenbosch.
FOOD AND AGRICULTURAL ORGANIZATION, 2006. Major food and agricultural commodities and producers. http://www.fao.org/es/ess/top/commodity.html,
21/11/2006, 3:00.
22
K ARSTEN , M.C. 1955. The old Company’s Garden at the Cape and its
Superintendents. Maskew Miller Limited, Cape Town.
PERSONAL COMMUNICATION
R A B I E , A. 2007. Chairperson of the South African Olive Growers’
Association.
Further information can be obtained from
Directorate Plant Production
Private Bag X250
PRETORIA 0001
Tel:
+27 12 319 6072
Fax:
+27 12 319 6353
E-mail: [email protected]
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