Nutmeg

Myristica fragrans

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Description

Nutmeg, Myristica fragrans, is a tropical evergreen tree in the family Myristicaceae grown for its seeds which are used as spices. The nutmeg tree has natural conical shape with a grey-brown trunk and dark green glossy leaves. The branches of the tree spread in whorls and the leaves are oval or lanceolate in shape. Leaves are arranged alternately on the branches and are 5–15 cm (2–6 in) in length, smooth and lighter in color on the under side. The tree produces a clusters of numerous male flowers whereas the female flowers are produced solitary or in a maximum cluster of 3. The flowers are pale yellow and fragrant. The fruit of the nutmeg tree is a rounded fleshy berry which splits into two halves when it ripens. The seed inside is shiny dark brown and oval in shape. The seed coat is covered by lacy red aril which is attached at the base of the seed. Nutmeg trees can reach a height of 20 m (66 ft) and may live for upwards of 80 years. Nutmeg may also be referred to as mace and it is not known in a wild state. It likely originated from the Moluccan Islands, particularly the volcanic island of Banda.

Uses

The seed of the nutmeg berry (nutmeg) and the aril (mace) are dried and used whole or ground as culinary spices.

Propagation


Basic requirements
Nutmeg is a tropical plant and requires dry periods to flower. It will grow best at temperatures between 20 and 30°C (68–86°F) and can tolerate a range of soils provided that the are well draining. Trees will grow optimally in a deep loamy sand rich in organic matter with a pH between 5.5 and 7.5. The trees love heat but should be protected from strong afternoon sun and also require some shelter from wind.

Propagation

Seeds
Trees grown from seed do not flower until they are between 6 and 8 years old and sex cannot be determined until this time. For this reason, 2–3 seedlings are planted in one place in commercial production and excess male trees are removed or replanted when they can be identified as they will not produce fruit. Seeds should be planted immediately harvest. They should not be allowed to dry out prior to planting. Seeds are commonly planted 6 × 6 m (20 × 20 ft) apart and thinned when required. A spacing of 10 × 10 m (33 × 33 ft) is desirable for fully grown trees. In the home garden a male and female tree are required for fruit production and they should be spaced at least 10 m (33 ft) apart. The tree will reach full size after about 20 years.

Marcotting
Nutmeg trees can also be grown from marcotted material. Vigorous branches are selected from female trees. The branches should be 1.2–1.5 cm in diameter. The branch is then split longitudinally in an area that is approximately 90 cm (35 in) from the end of the branch. Each split should be approximately 5 cm (2 in) in length. A bamboo splint is positioned along the area of the split to secure the branch and prevent it from breaking. A small piece of the split branch is then removed on the bottom side of the branch. This piece is approximately 6–12 mm (02–0.4 in) long. The remainder of the split is held open by placing a piece of hardwood to act as a wedge. Finally, the exposed piece of branch is dusted with rooting powder and wrapped in moistened peat moss, coconut coir or similar and sealed in polyethylene sheeting. Marcotted branches usually develop roots in 4–12 months. once an adequate root system has developed, the branches are severed from the tree and potted.

Planting
Nutmeg trees should be planted in an area with adequate shade to protect the young trees while they establish. Shading is commonly achieved by intercropping with other crops such as cocoa or banana. Marcots are planted in holes which are approximately 60 × 60 cm (24 × 24 in). Composted manure is worked into the soil and the trees are set in the holes. Stakes are used to protect the newly planted trees.

Harvesting
Fruits are harvested when they are open by using a blade attached to the end of a long pole. A basket is also attached to the end of the pole such that when the fruit is cut from the tree with the blade, it drops into the basket. Seeds may also be collected from the ground after they have dropped from the tree but this encourages crop losses through disease.

Diseases

Cocoa weevil Insect Araecerus fasciculatus

Symptoms

Circular bore holes on nut shells where adult has emerged; kernel destroyed by tunneling or completely hollowed out; adult is a small (3-5 mm) long beetle which is a mottled dark brown in color; larvae are small yellow-white grubs grubs

Comments

Cocoa weevils are potentially devastating post-harvest pests; larvae bore into the kernels to feed and pupate; adults bore an exit hole after pupation and emerge from the kernel

Management

The primary method of controlling the cocoa weevil is through the use of fumigants on the stored nuts

Leaf spot (Shot hole) Fungus Colletotrichum gloeosporioides

Symptoms

Sunken spots with yellow halo on foliage; center of spots dry out and drop from plant resulting in holes in the leaves (shot hole)

Comments

Management

Application of 1% Bordeaux mixture can help to control the disease

Thread blight Fungi Corticium spp.

Symptoms

Fungus causes two different types of thread blight; the first type appears as fine white hyphae which aggregate to form threads arranged in a fan shape along the underside of leaves; the second type of blight is known as horsehair blight and appears as silk-like black threads which form an irregular network on stems and leaves

Comments

Fungi survive on dried leaves; disease emergence is favored by heavy shading of plants

Management

If infection is severe it can be treated with 1% Bordeaux mixture; avoid shading plants and follow good sanitary practices to limit spread

References

CABI Crop Protection Compendium. (2008). Myristica fragrans (nutmeg) datasheet. Available at: http://www.cabi.org/cpc/datasheet/35361. [Accessed 25 February 15]. Paid subscription required.

Marcelle, G. B. (1995). Production, handling and processing of nutmeg and mace and their culinary uses. Food and Agricultural Organization of the United Nations. Available at: http://www.fao.org/docrep/x5047E/x504.... [Accessed 25 February 15]. Free to access.