Fruit trees: Olive tree

Fruit trees: Olive tree

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The area of ​​origin of the olive tree (Olea europaea L. is believed to be the South Caucasian one (12,000 BC) although many consider it a purely Mediterranean plant. This, in fact, has taken place very well in the Mediterranean basin especially in the orange belt where the main crop is that of citrus fruits associated in every way with that of the olive tree: this belt includes countries such as Italy, the south of Spain and France, Greece and some Middle Eastern countries bordering the eastern Mediterranean.
Cultivated Lolivo belongs to the vast family of oleaceae which includes as many as 30 genera (including the Ligustrum, Syringa and Fraxinus); the species is divided into two subspecies, cultivated lolivo (Olea europaea sativa) and loleastro (Olea europaea oleaster).

Olive grove in Tuscany (website photo)

Botanical characters

Lolivo is a very long-lived plant that can easily reach several hundred damages: this characteristic is mainly attributable to the fact that it is able to regenerate completely or in large part the epigean and hypogeal apparatus that are damaged. Lolivo is also an evergreen plant, i.e. its vegetative phase is almost continuous throughout the year, with only a slight drop in the winter. I begin the description from the epigean area up to the hypogean one.
Lolivo is a typically basitone species, that is, which assumes the typically conical shape without anthropic intervention.
The gems they are mainly of axillary type: it should be noted that in very vigorous plants, in addition to flower buds (they produce fruits with only the origins of productive organs) and wood, you can also find mixed buds (which produce both flowers and leaves and branches).
THE flowers they are small, white and perfume-free hermaphrodites, made up of calyx (4 sepals) and corolla (4-petal white gamopetala). The flowers are grouped into pinkies (10-15 flowers each) which are formed from mixed buds present on branches of the previous year or on those of that vintage. The pinky is scaled and begins quite early in the part facing south. Pollination is anemophilous or obtained thanks to the transport of wind pollen and not by means of pollinating insects (entomophilous pollination).
The leaves they are lanceolate in shape, arranged in verticils orthogonal to each other, leathery. They are glaucous and glabrous green on the upper page while they have starry hairs on the lower one which give it the typical silver color and in turn preserve it from excessive perspiration during the hot Mediterranean summers.
The fruit it is an oval drupe and important is that it is the only fruit from which an oil is extracted (the other oils are extracted by chemical or physical processes from seeds). Usually ovoid in shape it can weigh from 2-3 gr for oil cultivars up to 4-5 gr in table cultivars. The peel, or exocarp, varies its color from green to purple unlike the different cultivars. The pulp, or mesocarp, is fleshy and contains 25-30% of oil, collected inside its cells in the form of small droplets. The seed is contained in a woody endocarp, also ovoid, rough and brown in color: it is easy to find kernels without an embryo, especially in the Montalcino and Rossellino cultivars, which causes a depreciation of the product.
The trunk is twisted, the bark is gray and smooth but tends to crumble with age; the wood is of a fine texture, yellow-brown in color, very fragrant (precisely oil), hard and used for the manufacture of fine solid wood furniture. Characteristics of the trunk, since its youthful shape, is the formation of hyperplasias (ova, mamelloni, dolls) in the collar area just below the ground surface; similar structures can also be found on the branch: however these formations are given not by parasitic factors but by hormonal imbalances and by microclimatic events.
The roots they are mainly of the taproot type in the first 3 years of age, from the 4th year on they are almost completely transformed into adventitious, superficial roots that guarantee the plant an excellent vigor even on rocky soils where the soil layer containing nutrients is limited to a few tens of centimeters.

Olive flowers (photo Francesco Sodi)

Phenological stages - Production alternation

Important to identify in the olive tree are the phenological stages and the alternation of production.
The phenological stages that the olive tree must follow are:
1. winter stage during which the buds are stationary
2. vegetative awakening of the buds
3. formation of the little fingers with the flower not yet developed but has the flower buttons
4. increase in the volume of the buttons
5. differentiation of the corolla from the calyx
6. real flowering with opening of flowers (white corollas)
7. fall of the petals (brown corollas)
8. moment of fruit set and appearance of fruits from the glass
9. enlargement of the fruit
10. veraison and hardening of the core
11. fruit ripening

The alternation of production is an aspect that must be taken into consideration in olive growing because its effects affect both the price and the quality of the finished product (both oil and table olives).
The causes to which this event can be traced are a mix of climatic conditions, parasitic attacks, pruning and wrong fertilization, excessive delay in the harvest of the fruits and no less important the predisposition of the cultivar itself. To remedy this event, it is necessary to operate promptly and continuously over time with the following measures:
1. regular distribution of production on the plant with extraordinary pruning interventions (annular incision);
2. practice of irrigation and continuous fertilization throughout the year;
3. carrying out a regular pest control, especially against the olive fly;
4. anticipating as much as possible the harvest time.

Rootstocks and varieties

As rootstocks can be used oleasters (from wild olive trees, once used) and olive trees (from rustic and vigorous cultivars, today the only subjects used). The latter, obtained from seeds of cultivated plants, like all the Franks, have a large non-homogeneous development, more accentuated in the olive tree due to the fact that numerous varieties are self-sterile. From this it can be deduced that identifying a population of seedlings capable of being uniform and controlling some characteristics is somewhat difficult. Alongside the Olea europaea, a certain success has been obtained by resorting to the Olea oblonga, a species resistant to Verticillium dahliae, a pathogen very common in the south. The research of new rootstocks has also been directed towards other species of the genus Oleae towards similar genera.
As for cultivars, the parameter that is most used in the classification of olive cultivars and that which divides them in relation to the destination of the fruit; on the basis of what they stand out, among the many:
- oil cultivar: Bosana, Canino, Carboncella, Casaliva, Coratina, Dolce Agogia, Frantoio, Leccino, Moraiolo, Pendolino (Tuscan cultivar popular as a pollinator of Frantoio, Leccino, Moraiolo, Ascolana Tenera), Rosciola, Taggiasca, etc .;
- table cultivars: Ascolana Tenera, Oliva di Cerignola, SantAgostino;
- dual-purpose cultivars: Carolea, Itrana, Tonda Iblea.


Before planting the olive trees and after choosing the place where the plant will have to be carried out, the following operations must be carried out:

1) leveling and, if necessary, stone removal;

2) deep tillage with ripper to till the soil in depth;

3) then continue with a manure-based fertilizer (300-400 quintals / hectare) and a phospho-potassium fertilizer (150-200 kg / ha);

4) installation of a drainage network (ditches and drains);

5) tracing the sixths and placing the tutors (wooden pegs) of future seedlings;

6) possible transplanting pruning of the seedlings.

The recommended period is the beginning of spring, preceding the vegetative restart (in the mild winter areas it is advisable to plant in the autumn). The plants that we have placed in the field will have to be bred with particular shapes and sixth planting: in central Italy the sixth 5x6 or 6x6 is preferred, while in the south the sixth 7x6 or 7x7 is more widely used. In recent years, the dynamic sixth is being experimented, that is, an olive grove where the plants have sixth 6x3 until the 12th year, from the 13th onwards one row every two is replanted so as to obtain two 6x6 plants.

Forms from breeding

The forms of farming change from area to area, from variety to variety but, above all, depending on the type of harvest to be practiced. It should not be forgotten, however, that lolivo is a Mediterranean plant: as such it needs a lot of light and air and needs the greater mass of leaves to give good production results, which it produces on branches of a full year, to be renewed annually , avoiding, at the same time, the shadings that have sensitive and negative effects on the productive and economic results of the crop.
The vase shape is the most common among the olive growing systems. Once cut at a certain height from the stem, branches are started externally (in a different way) which will give the crown the shape of a cone, or cylinder, or conical-cylindrical, or truncated-conical. It is a system that allows a good aeration of the foliage avoiding excessive thickening of the vegetation. The polyconic pot, with the branches scaffolded at 1-2 m from the ground, allows the processing and the under-growth of the herbaceous species. At the same time, it allows plants to bear fruit very high, making pruning and harvesting operations difficult and expensive. When the plants have reached maturity, stairs are needed, therefore, other forms of farming are spreading. The free or bush form is obtained without carrying out any pruning intervention on the plant in the first 8-10 years, without prejudice to the possible thinning of the branches at the base for the first 40-50 cm, to be carried out immediately after transplanting or at the end of the first year. Following the development of the olive tree, a globoid bush with various buds and height content is obtained, similar to the natural shape. From the 10th year onwards, more or less drastic pruning interventions are foreseen, which can range from a lowering of the tops, with simultaneous thinning out of the crown, to a turnaround slitting of all the plants of the stubbing. In the globe, very similar in shape to the bush, the stem has been cut at a certain height and the branches develop from this plane without a predetermined order to reach different heights with ramifications; on the whole the foliage of the olive tree takes a globular shape.
When the branches do not descend very laterally, but extend only in the upper part, like those of the pine-nut pine, there is an umbrella. Among the low breeding forms we mention: the free palmette, the bushy vase, the bush enlarged along the row (elliptical) or expanded (circular), monocon or cord, hedged. These forms tend to create a continuous mass of vegetation along the row up to 4 m high. The bushy pot has 3-4 main branches which depart from the ground and can derive from groups of 3-4 seedlings. The mono cone is a shape at the top, very similar to the spindle used in fruit growing, with simple manual skills in pruning. For the setting of this form of training, we recommend summer training pruning in the first two years in order to eliminate the basal branches of the trunk in the first 80-90 cm, guide the top to the brace and suppress any upright lateral branches that can compete with the only top. The woody branches will be interspersed with each other by 50-60 cm in order to give the plant, when the structure is finished, the shape of a cone with the top facing upwards. It is the most suitable form of breeding for mechanical harvesting by vibration of the trunk, but fruiting is not always regular. Free breeding forms are more suitable for those companies that have little labor for pruning and harvesting operations.

Cultivation practices

To ensure good production, excellent production pruning must be carried out with few but fundamental rules in mind:

1) maintenance of the right balance between vegetation and fruiting;

2) lolivo produces on twigs of the year from 25 to 50 cm long;

3) an excessive production during a year causes an exhaustion of the nutrients available to the plant, favoring the alternation of production;

4) the hormonal competition between fruits of the same plant and of the same branch is the main factor that induces the pre-harvest drop.

There are two other, though less important, cultivation practices that are spreading lately: irrigation and fertilization. Of both olives it would not have a real need because it is a very rustic plant but which, to increase its production, have proven to be quite effective.
Irrigation is especially important in the early years of planting and in the summer. If the plant went into water shortages during the summer and spring, there would be anomalous openings of the flowers and consequent abortion of the ovary, in a reduced fruit size and little pulp compared to the whole fruit which would give less oil. To remedy this problem, traditional gravitational or micro-flow irrigation systems (spray and drop) are set up in the field.
Fertilization is important, as already mentioned, at the time of planting but also at the moment of full production if very high conversion ratios are to be obtained. There are elements that play a fundamental role in the nutrition of these plants and are: Bo and Mg (together with iron they are used for the mineral nutrition of the plant), Ca, K (favors the synthesis of starch, regulates water accumulation and increases resistance to environmental adversities), P (regulates growth and fruiting) and K (regulates the vigor of the plant and regulates its vegetative-productive balance).


For olives there is no precise time of harvest. The olives are divided, depending on the ripeness of the fruit, into: gradually scaled, simultaneously ripened.
Furthermore, unlike their earliness, they are divided into: early (Leccino, Rosciola and Moraiolo), medium-early (Cardoncella) and late (Frantoio).
For oil olives it is decided to carry it out (usually from mid-October to the whole month of December) when the fruits have reached maturity: which is deduced from the veraison of the exocarp (typical and different between cultivars and cultivars); in table olives, the picking can be carried out both before and after the turning (depending on the processes they will have to undergo).
It is important, especially for oil olives, to estimate the time of their harvest well, keeping in mind some considerations:
- the pre-harvest drop due to significant losses on future oil production; however, the product obtained from cascolate olives is of poor quality: in cultivars subject to this phenomenon, it is advisable to anticipate the harvest;
- anticipating the collection avoids both damage from atmospheric events and parasitic attacks;
- olives harvested early, with maturation already completed, have both a more pleasant taste and lower acidity and better oil yield;
- the prolonged permanence from the olives already ripe on the plant leads the new buds to not differentiate, thus favoring the alternation of production.
The olive harvest can be done either manually or mechanically. The manual is divided into three different types;
- picking: the fruits are removed thanks to the only help of the hands and are deposited in baskets or baskets. It reaches 5-10 kg / h of oil olives up to 10-20 kg / h for table olives;
- combing: the drupes are combed or swiped with tools called combs, mansalva and manrapida, and dropped on sheets or nets placed under the trees. The yield is around 15-25 kg / h for both categories.
- picking up: practiced mainly in Liguria, Puglia and Sicily and consists in collecting lolives when they have fallen naturally without having to intervene with labor as in the previous cases.
Instead the mechanized one is implemented with the following types of machine:
- oscillating hooks or combs which, driven by compressors and carried to the ends of the rods, allow to double the hourly output;
- shakers to be applied to the gills or directly to the trunk. There are shaker-harvester machines on the market that combine the shaker apparatus with that of interception of the product.

Biological adversities

The main biological adversities are given both by damage agents (insects) and by disease agents (fungi or bacteria). Those caused by disease agents are mainly three:
Cycloconium or peacock eye: (Cycloconium oleaginum) this is one of the most important and harmful diseases of fungal origin that attack the olive tree: in fact it mainly affects the leaves but does not spare the branches or the fruits. On the leaves it manifests itself with 10 mm roundish spots consisting of concentric polychromatic circles (from yellow to brownish) that draw peacock eye and cause phylloptosis effects on the affected plants; on the fruits the symptoms are more occasional and less dangerous and manifest themselves as small sunken and punctiform black specks; the twigs are attached only on the herbaceous part and the symptoms manifest themselves similar to those of the leaves. The fight is chemical, both guided and integrated: it provides a sampling of the leaves to determine the intervention threshold (30-40% of the collected leaves): if the threshold is reached or exceeded, one intervenes with a treatment in February-March and one in October based on cupric (Bordeaux mixture, copper hydroxides) or dithiocarbamates (Zineb or Ziram).

Olive leprosy: (Gleosporium olivarum) the disease occurs mainly in the autumn when the rains begin. This affects the fruits in the process of ripening and large, rounded, wrinkled, blackish brown spots are formed, with chalky or waxy pustules of brown or pinkish color. The affected olives fall to the ground or, in any case, provide a poor quality oil (reddish, cloudy and acidic). The disease can also affect young twigs and leaves on which yellowish spots form which later turn to brown: the affected leaves dry out and fall off. The struggle we can carry out is preventive, both agronomic and chemical. The chemical fight takes place in autumn with treatments based on copper products (copper hydroxides or Bordeaux mixture) or with Clortalonil; the agronomic one is put in place by providing the plant with a good drainage system to remove excess water or by thinning the foliage in order to avoid the formation of a humid microclimate, which would favor the pathogen.

Olive mange: (Pseudomonas savastanoi) is one of the main known bacteriosis and attacks the branches, the leaves, the roots on which the damage is more relevant than on the other parts of the plant, the trunk and the fruits on which they manifest themselves or deformations or spots ; it presents with cracked, hard and brown tubercles caused by openings produced by adversity, infections or trauma. The high spring rainfall accompanied by mild temperatures favor the activity of the pathogen. The damages are due to the removal of plastic materials with a consequent decrease in their production of up to 30%. As a consequence of this attack, there was also a certain deterioration in the quality of the olives and oil. The fight against the olive mange is preventive only agronomic and takes advantage of the following precautions: pruning of rimonda and destruction of the infected branches, the product is not collected by beating, protecting and disinfecting the wounds, fighting Dacus oleae which is the vector of such bacteriosis is dendrosurgical practices.

Xylella fastidiosa (agent of the rapid olive drying complex - CoDiRO): In the summer of 2013, several cases of drying of olive trees grown in an area south of Gallipoli in the Province of Lecce were reported in some Apulian olive groves.
The affected plants had the following symptoms:
- extensive drying of the crown that affected isolated branches, entire branches and / or the whole plant;
- internal browning of the wood at different levels of the younger branches, branches and stem;
- leaves partially dried in the apical and / or marginal part.
Following the investigations carried out by the Phytosanitary Service of Puglia with the support of the University of Bari and the CNR, various parasitic agents have been identified in the affected area which are associated with the so-called "Complex of rapid drying of the olive tree"; they are: the phytopathogenic quarantine bacterium Xylella fastidiosa ,; the moth Zeuzera pyrina or yellow Rodilegno and some vascular lignic fungi (Phaeoacremonium parasiticum, P. rubrigenun, P. aleophilum, P. alvesii and Phaemoniella spp.) known to cause drying of woody parts of arboreal plants and vines.
Xylella fastidiosa is a bacterium included in the list of quarantine pests of the European Union (Annex I AI of the Council Directive 2000/29 / EC) which was found for the first time on the Community territory.
Considering the risk of its spread due to its danger to numerous cultivated and spontaneous plant species, this has triggered a series of community, national and regional actions aimed at eradicating the Apulian outbreak and limiting its spread throughout the national territory. Go to the file

The main diseases caused by damage agents are five, namely:
Olive fly (Dacus oleae)
The larva of the olive fly measures about 8 mm, is apoda, has a chewing apparatus consisting of two black jaws clearly visible to the naked eye, is yellowish in color and is thinner towards the cephalic end. The adult insect resembles a small fly (4-5 mm) with a wingspan of 10-12 mm., Has fawn head with greenish eyes, body.
The body is gray in color and transparent wings with two small dark spots on the ends. The feeding of this diptera differs according to the stage in which it is found: from larva it feeds on the pulp of the fruits within which it digs tunnels (the fruits thus damaged are home to rot and consequent drop due to the establishment of colonies of microorganisms); as an adult it feeds on the juices that come out of the oviposition puncture, with sugary or protein materials that extract from the different green parts of the olive tree through its typically pungent-sucking mouthparts. The olive fly is one of the main vectors of the olive mange. The fight is both chemical and, in recent years, biological control methods carried out with the intervention of entomophages are being tested. Remember that Dacus oleae is very affected by the alternation of temperature (limiting factor): in fact, flight activity begins when the temperature exceeds 14-18 ° C and stops when it exceeds 31-33 ° C; moreover, the succession of summer days characterized by high temperatures (higher than 30 ° C), low humidity and absence of rain cause a high mortality of the eggs and larvae present inside the fruits, halting the development of the eggs and the activity of the adults. The entomophages used in the experimentation are larval parasitoids (Hymenoptera Calcidoidei), entomoparasites (Hymenoptera Braconide) and insects that feed on its eggs (Diptera Cecidomide); the chemical struggle combines the principles of the integrated and the guided type: the intervention threshold is set which varies according to and according to the use for which the production of the representative sample calculated in drupes per Ha is intended (200 drupes collected at random, coming from from 20 plants). The detection of adults is carried out with chromotropic traps, food (poisoned, before the laying begins) and sexual (installed in late June, 2-3 per hectare).

Olives affected by olive fly

Olive thrips: (Liothripis oleae) this is a very widespread species in the Mediterranean basin. The adult is about 2.5-3 mm long, has a bright black body and fringed wings. The nymphs are yellow. The damages occur on the shoots, leaves, flowers, fruits and are determined by the trophic punctures of both adults and youthful forms. The affected buds have a stunted development, the leaves are deformed and fall prematurely, on the flowers there is a flower bud and subsequent pouring. Sporadic drops can occur on the fruit, but deformations, pits and spots are much more frequent. The stings can also promote the penetration of wound pathogens. The fight against this herbal tea is chemical, agronomic and also conducted with the help of two entomophages of the Liothripis, that is Anthocoris nemoralis (Rincote anthocoride) and Tetrastichus gentilei (Hymenoptera calcidoideo). The chemical struggle is carried out only in the presence of serious attacks and phosphorganic products such as Acefate and Metomil are used (an intervention threshold equal to 10% of the infested buds is established). The agronomic struggle is limited to good prunings to prevent the establishment of the Tripide.

Cochineal half a grain of pepper: (Seissetia olea) this is a lacanide which has as its main hosts lolivo and citrus fruits, but nevertheless lives on various other arboreal and herbaceous plants including: oleander, judas tree, euonymus, lentisk, aralia, palms, pumpkin and spontaneous carduacee. The infestations affect the branches, the twigs and the lower page of the leaves, where the nymphs are located along the main rib. The mealybug causes vegetative deterioration, defoliation, desiccation of twigs, fruit drop and poor fruiting. The neanid is yellowish in color and darkens during development; the male is winged and rarely appears, the female is ather about 5 mm in size and its body is completely covered with a convex wax shield (under which the eggs develop) with an H drawn over it. The abundant sugary excrements produced by the females develop both a remarkable fusaggine and a slow effect that burns the point of the leaf on which it is found, as well as a strong food call for ants. The development of cochineal is favored in the vintages with mild autumn and winter and with humid and not excessively hot summer, as well as in plants neglected and subjected to excessive contributions of nitrogen fertilizers. Furthermore, the high density of planting and the reduced or lack of pruning create micro-environmental conditions which are particularly favorable for the development of infestations. The fight against this very harmful Rincote is both agronomic and chemical: however it follows the principles of integrated and guided struggle. The chemical method provides for an intervention threshold equal to 2-5 nymphs per sheet or 1 female every 10 cm of sprig, if it is exceeded it is used with phosphorganics and white oils (the use of the former is avoided due to the high toxicity even towards a useful lentomofauna the latter is preferred for the opposite reason). The agronomic struggle makes use of energetic pruning and low nitrogen fertilization.

Cochineal cochineal of the olive tree or Filippa: (Lichtensia viburni) this Coccide is present in all the different Italian olive regions causing serious damage especially to the aerial part of the olive trees. The male is winged, the nymphs are yellow-greenish and oval in shape, the adult female is 5 mm long with the body yellowish with dark spots: during the placement their body appears covered by a waxy secretion (ovisacco) where the eggs are contained. The parts infested by Lichtensia are the lower part of the leaves and buds: the damage caused consists of the production of honeydew which brings the same drawbacks as the cochineal half a grain of pepper. To eradicate this annoying and harmful insect, both prey / predator ratios present in nature (Coccinellidae beetles) and chemical control criteria (products that are the same as for C. mg p.) And agronomic control criteria are used (pruning thinning).

Olive moth: (Prays oleae) this insect has mainly three annual generations (larva, chrysalis and adult butterfly), which attack the leaves, flowers and fruits respectively. The larva, 6-8 mm long and 1.5 mm wide, has an ash green color with a reddish head. The chrysalis is brown in color and has a length of 4-6 mm. Ladulto is a small white-colored butterfly, 6-7 mm long; the first pair of wings is characterized by small dark spots, while the second is uniformly gray in color with a characteristic jagged edge. the first generation begins with the caterpillar, in the late winter it digs tunnels in the leaves, subsequently it erodes the tender leaves and towards April it becomes a pup in a cocoon. The second generation penetrates into the floral buds (little fingers) and is incisalida. The third generation is the one that causes the most serious damage, causing the fall of the olives and causing heavy losses. The damage is similar to that of the fly larva, in fact it enters the drupes, digging tunnels that also erode the core: here is the difference compared to the fly tunnels. Looking at the affected olives, the larvae and the pupa are easily distinguished from those affected by the fly. The fight is chemical and follows the indications of the guided and integrated one: predatory entomophagous insects (Rincoti Anthocorids, Diphtheros Silphids and Neuroptera Chrysopids) and parasitoids (Hymenoptera Calcidoidei and Hymenoptera Braconids) are used; the chemicals used are all phosphorganics. In some cases Bacillus thuringiensis is used.

of Dear Alberto

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