Litchi Tree.

Litchi, also spelled Lychee

Litchi sinensis

Origin:

Native to southern China where it has been cultivated for millennia. It is now grown in numerous countries worldwide, including Australia.

Climate:

It is a sub-tropical plant, ideally having cool dry winters and warm and humid summers with annual precipitation of 1250-2000mm. Dry conditions during winter are very important to encourage flowering. Frosts may kill young trees and even when mature, tolerance is limited. The low temperatures associated with seasonal climates stimulate flowering as none occurs at 20-25°C. It can withstand brief flooding.

Plant Description:

Litchi is a long–lived but slow-growing evergreen spreading tree with brittle branches, 8-11m tall. The deep green alternate leaves are compound paripinnate with 2-5 pairs of opposite elliptical leaflets, 7-15cm long and 2-5 cm wide. Growth occurs in several flushes each year, with young leaflets coloured bronze-pink.

Relatives:

Sapindaceae Family, related to rambutan, longan, mamoncillo, pulasan, and others.

Soils:

A wide variety of soils is acceptable if well-drained, even slightly alkaline calcareous soils. However, ideal pH is 5.5-7 as above this level micronutrient deficiencies may develop. Important mycorrhizal associations can form in acid soils.

Propagation:

The recalcitrant seeds should only be used to produce rootstocks for grafting. They are most commonly propagated by air layering. Grafting is also possible, but some combinations have varying degrees of incompatibility. Marcotts are very delicate for the first few months after separation from the parent and should be grown on for 6-12 months and then hardened before in-ground planting.

Cultivars:

Names are confused but some are: Bengal (consistent bearer, large seed), Wai Chee (erratic in warm humid areas), Haak Yip (medium sized seed), Salathiel (No Mai Chee, consistent, small seed), Brewster (erratic), and Bosworth 3 (consistent). Characteristics of different cvs are not directly transferable to different climates and it is wise to select those which are known to produce well in your area.

Flowering and Pollination:

Inflorescences occur as terminal panicles. The numerous yellow-green or brown yellow flowers are apetalous with a fleshy disc and up to 8 stamens. There are 3 sexual types of flowers. The first to develop is functionally male (I), the next is hermaphrodite but functions as a female (II) and the third as male (III). Two thirds of the flowers on a panicle are type III and only 20% are type II, with the ratio varying for different varieties. Males shed pollen for several days and generally only one lobe of the ovary develops into a fruit. Bees are the dominant pollinators, giving up to 11% fruit set. There is some self-sterility.

Cultivation:

They grow best in full sun. Young newly planted trees should be well-watered and protected with shade screens. They can be damaged by high N fertilizer so only use a slow release form. When mature, water is withheld during flower initiation in late summer-early autumn, but once fruit have set, high moisture levels must be maintained through to fruit maturity. Similarly, fertilization is withheld in this period to prevent vegetative growth. The main application of NPK is given after harvest, with amounts increasing with tree age. The number of leaves in a panicle determines the number of fruit so it is important to stimulate vegetative growth after harvest.

Wind Tolerance:

They should not be planted in exposed sites without some form of protection.

Pruning:

When young, all low branches should be removed and 4 well-spaced branches selected to form the main framework. Remove any branches that have a narrow crotch angle. When mature, branch terminals are headed back to control size, allow light penetration and encourage growth of bearing terminals.

The Fruit:

Round or oval, 2.5-4cm long, 2-30 per panicle with a thin yellowish to bright red leathery skin with pointed protuberances. The skin peels easily to reveal the edible flesh (aril) which is white-translucent, very sweet and contains a single glossy dark brown seed that varies in size according to the variety. Some fruits have aborted seeds. They have reasonable levels of vitamin C and contain 20-25% carbohydrates.

Fruit Production and Harvesting:

Seedling grown trees may bear after 6-10 years and vegetative plants in half this time. They can be notoriously irregular bearers plus there is usually major fruit drop. But with well-managed trees, yield can steadily increase with age so that a 7-8 year old could produce 45kg and very old trees several times this amount. Fruit are picked by cutting off the whole panicle when fully coloured as they don’t ripen afterwards. Individual trees ripen over a few weeks but different cvs can extend the range of harvest times.

Fruit Uses:

Usually eaten fresh but can be dried, frozen, pulped or processed. Freshly picked litchis can be stored for about 2 weeks in a fridge but only 2-3 days at room temperature. Removal of the large seed allows the fruits to be stuffed with various fillings.

Pests and Diseases:

Generally minimal, but some possible problems include scales, mites, aphids, anthracnose, leaf-curl and birds.

Comments:

Fresh litchi fruit appeals to almost everyone. The biggest challenge in WA with our Mediterranean climate of wet autumn-winter conditions is to attain sufficient flower bud initiation for consistent flowering and fruit set, and then to keep up the moisture levels through our dry summers till harvesting to avoid major fruit drop.