ALMOND TREE: CHARACTERISTICS, HABITAT, CULTIVATION, VARIETIES - SCIENCE - 2024

The almond tree (Prunus dulcis) is a deciduous tree that belongs to the subgenus Amygdalus of the Rosacea family and of the Rosales order. Native to Asia Minor and feral in the Caucasus and Greece, it adapts to the agroclimatic conditions of the Mediterranean.

This species is a medium-sized tree with deep roots, a sinuous trunk, hard wood and an irregular crown. The leaves are oblong and slightly serrated, the five-petal flowers are white or pink, and its fruit is the traditional almond.

Almond Tree (Prunis dulcis). Source: צילום: ד דר אבישי טייכר

The cultivation of the almond tree is carried out primarily by its seed, rich in fatty acids, vitamins, amino acids, mineral elements and proteins. In fact, the largest almond producers worldwide are the United States, Spain, Australia, Tunisia, Iran, Morocco, Syria and Turkey.

There is a great diversity of varieties that are distributed according to their adaptation to certain climatic conditions. Likewise, these varieties can be organized into two large groups, one with a "soft shell" and the other with a "hard shell".

The almond is the edible fruit of the almond tree, and is consumed fresh, toasted, cooked or smoked, being the ideal complement to various traditional dishes. They are widely used in confectionery to make nougat, cakes, marzipan, sweets, caramelised and candied almonds.

On the other hand, an oil used exclusively in cosmetology is extracted from the almonds, as well as a milk with a high protein content called "almond horchata". In addition, the firm and reddish wood is used in cabinetmaking, the fruit cover is used as forage and the peel as a food additive.

Caracter í general sticas

Plant

- Subgenus: Amygdalus

- Species: Prunus dulcis (Mill.) DA Webb

Etymology

- Prunus, a generic name that comes from the Greek «προύνη» and the Latin «prūnus», referring to the wild plum.

- dulcis, specific epithet that derives from the Latin «dulcis-e», which means sweet, pleasant or delicious, due to its fruit with a pleasant taste and aroma.

Ripe almonds. Source: באדיבות אתרצמח השדה

Synonyms

- Amygdalus dulcis Mill.

- Prunus amygdalus (L.) Batsch

- Amygdalus communis L.

Habitat and distribution

Prunus dulcis is native to central and southwestern Asia where it is found in the wild throughout the mountainous areas. In fact, it is common in the Tain Shan mountains and Kurdistan, up to Afghanistan, Turkestan, Mesopotamia and Persia.

There is written evidence of its cultivation since 350 BC On the other hand, it is presumed that its origin is due to the cross between the wild species Prunus bucharica and Prunus fenzliana.

Its dispersion through the Mediterranean basin was thanks to the intervention of the Arabs, Phoenicians, Greeks and Romans. The Phoenicians brought its seeds from the East, the Greeks and Romans cultivated it, and the Arabs completed their expansion during the 7th century.

In Spain the almond tree has been cultivated for 2,000 years, introduced by the Phoenicians and propagated by the Romans. In the middle of the 18th century it was taken by the Franciscan friars to the missions of the New World, specifically to California.

It is naturally found in Southeast Asia and North Africa. As a commercial crop it is found in Spain, Portugal, France and Italy, as well as a foreign species in California, southern Africa and Australia.

Unripe fruits on an almond tree. Source: 3268zauber

In Spain it is produced as a crop for agricultural use in regions outside the Mediterranean, Andalusia, Murcia, the Valencian Community, Catalonia and the Balearic Islands. However, in the central or northern region, it is planted as an ornamental crop, since the strong winter limits the ripening of the fruits.

This crop adapts to the warm Mediterranean climate, between 30º-40º latitude North and South, and mild and humid winters. In fact, it supports intense cold of down to -20º C at rest, hot and dry summers with rainfall less than 600 mm.

Culture

Requirements

The cultivation of the almond tree adapts to typically Mediterranean climates, being resistant to hot summers and cold winters. In addition, it supports prolonged periods of drought, and adapts to sandy, limestone, dry soils of low fertility.

The best crop productivity occurs in dry and warm temperate climates, loose, deep, fertile soils with a neutral pH. Indeed, it requires an average depth of one meter and altitude levels between 100-2,000 meters above sea level, 1,000 meters above sea level being the optimum elevation.

Spread

The almond tree reproduces sexually from seed, or vegetatively through grafting. Propagation by seed is the usual method to achieve vigorous and leafy trees, being the appropriate technique to keep local varieties active.

In addition, the use of seed from healthy and strong plants allows to produce frank rootstocks for the vegetative reproduction of highly productive varieties. The rootstocks are obtained from both bitter and sweet almonds, the most common being GF 677 and PS A6.

The GF 677 rootstock adapts to a wide variety of soils and environmental conditions, induces vigor, accelerates flowering and increases productivity. PS A6 guarantees fast flowering, but is less resistant to drought and is sensitive to fungal attacks.

In commercial farms the recommended sowing spacing is the sixth 6 x 6 m between plants and rows. This provision favors the implementation of intensive and agro-ecological production techniques, as well as the mechanization of handling and harvesting.

Almond blossoms. Source: pixabay.com

Driving

During the flowering period, the almond tree requires protection against spring frosts that affect the production and ripening of the fruits. In fact, the use of resistant varieties, physical methods (smoke or fog) or natural products based on non-ionic surfactants is recommended.

The almond tree in its growth, flowering and fruiting phases is sensitive to strong winds. It is recommended to establish the cultivation in areas with natural barriers or forest shields in order to avoid damages that condition its development.

Fertilization is essential to achieve maximum productive performance, being necessary to incorporate adequate amounts of nutritive elements based on soil analysis and foliar analysis.

The water supply through irrigation must not exceed the limits required by the crop, otherwise it could cause physiological damage. Also, in conditions of high rainfall the crop is prone to acquiring fungal diseases.

Pruning allows the formation or sanitation of the crop; This is how the training pruning allows to control the vegetative development of the plant. On the other hand, regeneration pruning allows aging branches to be rejuvenated and invigorated, in order to maintain their productive level.

Buds of almond flowers. Source: 4028mdk09

Diseases

Under certain conditions of high temperature and humidity, almond trees are prone to attack by fungi or phytopathogenic bacteria. Among the main diseases are dent, dry bud, screening, ocher spot, bacterial stain, moniliosis and rust.

Dent or leprosy

A disease that affects leaves and fruits in conditions of high rainfall whose causal agent is the ascomycete fungus Taphrina deformans. The leaves swell and deform, and the shoots become discolored, the preventive treatment being the application of systemic and contact insecticides.

Dry bud

Disease known as "dry" of the almond tree caused by the fungus Phomopsys amygdali, and appears through wounds after defoliation. The best control are preventive measures with healing, disinfection of pruning material and removal of diseased branches.

Screened or shot

A disease that affects the bark, leaves and fruits of the almond tree, caused by the imperfect fungus Stigmina carpohyla in conditions of high rainfall. The symptoms are rubbed spots that dry and detach, leaving a hole, being controlled through sanitation pruning or preventive fumigations.

Ocher stain

The symptoms are ocher-colored spots at the level of the leaves, which causes the subsequent defoliation of the tree. The causative agent is the Polystigma ochraceum fungus, its chemical control being applied by applying products such as capturing or eliminating the infected leaves.

Characteristic symptoms of ocher stain (Polystigma ochraceum) Source: Luis Fernández García

Bacterial stain

Bacterial disease caused by Xanthomonas arborícola pv. Pruni, its highest incidence occurs in conditions of high humidity. Control is the total eradication of the plant once the disease has been confirmed according to laboratory analysis.

Moniliosis

Symptoms appear on flower buds, causing wilting of flowers, as well as cankers at the level of leaves and branches. The causal agent is Monilinia laxa, its control is preventively using fungicides during and after flowering.

Rust

Disease promoted by the fungus Tranzschelia pruni-spinosae in high humidity conditions, causes circular spots on the leaves covered with a red-yellowish powder. The recommended control measures is the application of contact preventive fungicides and elimination of contaminated branches.

Varieties

The almond tree has a large number of varieties depending on the geographical areas and the climatic conditions of each region. This diversity has favored their great variability creating very dissimilar ecotypes, but with some common characteristics.

American ecotype

Types of almond trees derived from the «Non Pareil» variety characterized by a homogeneous, thick, elongated almond with light and smooth skin. Materials of this type have common features such as a medium flowering season and a soft shell.

Spanish ecotype

In this type, a group of varieties of very early or early flowering season with hard-shelled almonds stands out. Among these varieties stands out the «Desmayo Largueta» native to the Ebro Valley, made of elliptical-amygdaloid almonds of excellent appearance and taste quality.

These varieties are adapted to medium altitude levels, between 300-750 meters above sea level. In addition, the skin of the fruits is easily separated, so they are adapted to be roasted and for baking.

On the other hand, the «Marcona» variety, native to the province of Alicante, stands out, known as the classic almond, with early flowering and quality fruits. Almonds are rounded, with a high content of fatty oils, with a hard shell, used especially for nougat, sweets and snacks.

Almonds Source: pixabay.com

French ecotype

They are generally very late-flowering almond trees, but they have an early ripening period. They are characterized by having a single flower per bud and do not produce double almonds; Among the main varieties are "Flour en Bas", "Aï" and "Tardive de la Verdière".

Italian ecotype

It constitutes a group of almond trees with late flowering and a hard shell consistency, with a large number of double almonds per fruit. Among these varieties of self-compatible or self-fertile character, cylindrical fruits and short amygdaloid, "Genco", "Tuono" and "Filippo Ceo" stand out.

Tunisian ecotype

Typical varieties of the Sfax regio on the Tunisian coast, with dry climates and mild winters that promote very early flowering. They are varieties of early maturation, grains with high lipid content and few double almonds, the varieties "Achaak" and "Zahaf" stand out.

References

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4. Lavín, Arturo & Silva, Reina (2001) Fruit trees for the Interior Drylands. INIA Bulletin Nº 30. Behavior of Carozos and Pomáceas. Instituto de Investigaciones Agropecuarias Cauquenes, Chile. ISSN 0717-4829.
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