Vanilla

Description

Vanilla, Vanilla planifolia, is a fleshy perennial vine in the family Orchidaceae grown for its pods and seeds which are used as a flavoring. The vanilla plant has a long succulent stem and grows by wrapping around trees. The vine has alternate, fleshy oblong or lanceolate leaves which are rounded at the base. The plant produces flowers on short racemes, each possessing 6–15 flowers, and fruits which take the form of narrow, cylindrical pods (or beans), each possessing many small black seeds. The vanilla plant can reach a height of 10–15 m (33–49 ft) in height and has an economic lifespan of approximately 10 years. The plant is native to Central America.


Uses

Vanilla bean extract is used a flavoring in confectionery and baking. Essential oils extracted from the plant are also used in the perfume industry.


Propagation


Basic requirements
Vanilla is a tropical plant and will grow best in warm, humid climates at temperatures between 21 and 32°C (33.8–89.6°F). Vanilla requires a soil rich in calcium and potassium and will grow best in a soil which is light and well-draining, with a pH between 6.0 and 7.0. Vanilla is a climbing plant and should always be provided with a support to grow on. It is usually planted alongside a companion tree, known as a tutor tree which has the added benefit of providing it with shade. Vanilla grows naturally in forests, often in clearings and alongside rivers and lakes where the forest canopy is thinner.

Propagation
Vanilla is usually propagated vegetatively from stem cuttings from a mother plant which has not been allowed to flower. Cuttings are best taken during the dry season when growth of the vines is slower. A cutting of 1.5 m (5 ft) should be taken and planted at the base of the support tree after removing the lower leaves. Cuttings should be planted at least 2 m (6.6 ft) apart. If a support tree is being used, it is preferable to use a type with a high number of lower branches. Vanilla may also be grown on a trellis or support post.

General care and maintenance
Vanilla should be managed to keep the vines at a manageable height as left unchecked they will continue to grow to the crowns of the supporting trees. When the plants reach a height of 1.6–1.8 m they should be bent back over the nearest suitable branch and the end of the shoot planted back into the ground and covered with soil. Planting the end of the shoot encourages the growth of roots and the continual production of newly rooted shoots helps to maintain a healthy plantation. Shoots may also be cut at the desired height and planted next to the same tutor tree once the wound has dried to create a new rooted plant. Vanilla should be mulched with organic mulch such as grass clippings to help suppress weeds and conserve soil moisture. Vanilla will benefit from the addition of fertilizer but applications are unnecessary and are rarely made in commercial production. Vanilla is naturally pollinated by small mexican bees and, although pollination is possible if the bees are present, plants are usually hand pollinated to ensure production.

Harvesting
Vanilla is ready for harvest between 6 and 9 months after flowering when the pods are still dark green and the tip is beginning to turn yellow.


References

Augstburger, F., Berger, J., Censkowsky, U., Heid, P., Milz, J. & Streit, C. (2000) Vanilla. Natureland e. V. Available at: http://www.naturland.de/fileadmin/MDB.... [Accessed 22 April 15]. Free to access.

CABI Crop Protection Compendium. (2008). Vanilla planifolia (vanilla) datasheet. Available at: http://www.cabi.org/cpc/datasheet/56074. [Accessed 22 April 15]. Paid subscription required.




Common Pests and Diseases

Root and stem rot
Fusarium batatatis

Symptoms
Fungus causes brown lesions on roots which turn brown and dry out; plants begin to rot at the apical tip and stop growing; plant begins to produce new roots from apical tissue; if there is not enough moisture, stems dry out and crack longitudinally; cracks will eventually cover the whole stem and the plant will die
Cause
Fungus
Comments
Emergence of the disease is favored by excessive soil moisture, too much shading of plants, inadequate fertilization, over-crowding and drought stress
Management
Plant vanilla in well-draining soils and avoid overcrowding the plants; prune out infected plant parts; plant vanilla varieties that are tolerant of resistant to the disease

Anthracnose
Colletotrichum spp.

Symptoms
Small, sunken, dark brown spots on leaves, fruits, stems and/or flowers; infected fruits dropping from plants before they reach maturity; damage to fruit is more pronounced during warm and humid periods of the growing season; symptoms generally develop first on apical parts of plant and spread to leaves and stems
Cause
Fungus
Comments
Disease emergence is favored by excessive shading of plants and overcrowding
Management
Provide plants with adequate fertilization; application of an appropriate fungicicde, e.g. Bordeaux mixture, can help to protect the plant from the disease

Rust
Uromyces joffrini

Symptoms
Yellow to orange pustules on undersides of leaves which enlarge and coalesce causing the entire leaf to dry out; plant development slows and if disease is left untreated then plant becomes unproductive, defoliates and dies
Cause
Fungus
Comments
Rust is most common in traditional vanilla plantations where there is overcrowding, excessive shading of plants and excessive moisture
Management
Removal of some leaves from the plants allows better penetration of sunlight; disease can be controlled through the application of appropriate fungicides

Black rot
Phytophthora spp.

Symptoms
Water-soaked green to black rot of stems, leaves and/or pods; thin white mycelium may be visible in infected tissues; disease usually begins at the apical part of the plant and spreads to leaves, stems and all other parts of the plant
Cause
Oomycete
Comments
Disease emergence favored by prolonged wet weather, poorly draining soil, excessive shading of plants, overcrowded plants and lack of weed control in the plantation
Management
Plant vanilla using recommended spacing; control weeds around plants; remove infected parts of plants and destroy by burning; application of appropriate fungicide can help to protect the plants from disease