Information from these publications:
Growing Lychee in Hawaii. 1999. Zee, F., M. Nagao, M. Nishina, and A. Kawataba. Cooperative Extension Service Fruis and Nuts, F&N-2.
Lychee. 1997. Chia, C.L., R.A. Hamilton, and D.O. Evans. CTAHR Fact Sheet Horticultural Commodity no. 1.
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Scientific name: Litchi chinensis
Origin: Southern China
Lychee is a popular tree in Hawaii, valued for its delicious fruit. As its botanical name implies, Litchi chinensis originated in China. Lychee (also written litchi, li-chi) is a large, long-lived, subtropical, evergreen tree that bears fruit from May to August in Hawaii.
The first lychee plant brought to Hawaii was imported from China in 1873 by Mr. Ching Chock and planted on the property of Mr. Chun Afong at the corner of Nuuanu and School Streets on Oahu. It was known as the "Afong" tree and was initially considered to be the Chinese cultivar 'Kwai Mi' (or 'Kwai Mei'), but it was later identified as 'Tai Tso' (or 'Tai So').
Lychee is a round-topped, long-lived, subtropical evergreen tree growing to 40 ft (12 m) in height. Immature leaflets are pale green, often tinged with bronze or pink, turning dark green and leathery when mature. Leaves are pinnate with one to five pairs of leaflets. Flowers are small, greenish-white or yellow, lacking petals, and borne in large numbers on branched, terminal panicles up to 12 inches (30 cm) long. The fruit is a tubercled, oval to ovoid drupe about 1 inch (2.5 cm) in diameter by 11/4 - 11/2 inches (3-4 cm) long with rough, brittle, red skin. The fruit flesh is juicy, white, translucent, and gelatinous, and does not adhere to the seed. The single seed is usually large but occasionally small and shrunken or abortive. Such abortive seeds are often referred to as "chicken tongue" seeds.
Lychee is related to longan (Dimocarpus longan), rambutan (Nephelium lappaceum), and pulasan (N. mutabile). Longan fruit, known as "dragon's eye," is similar to lychee but smaller and rounder, with smoother, dull yellow to light brown skin, and a more aromatic, spicy fruit. Longan grows well in Hawaii, but fruiting of seedling trees is erratic. Rambutan and pulasan are more tropical in origin than lychee or longan.
Lychees are and probably will remain a favorite home garden tree in Hawaii, since there is hardly a more attractive ornamental fruit tree than a well shaped, dark green lychee tree heavily laden with clusters of bright red fruits. Although a few commercial lychee orchards have been planted in Hawaii, they are erratic in bearing habit and productivity.
Lychees are better adapted to subtropical than to tropical climates. In Hawaii, lychee can be grown in almost any type of soil from sea level to 2000 ft (600 m) elevation. Areas with 50-140 inches (127-356 cm) rainfall per year are suitable for lychees, but they can also be grown in drier areas with irrigation.
Lychee trees require well drained soil and grow best in acidic soil (pH 5.0-5.5). Short periods of soil waterlogging and light flooding are tolerated, but standing water is not. Lychee trees are susceptible to wind damage and need good wind protection.
Hawaii has many microclimates that vary considerably over relatively short distances. Careful site selection can make a great contribution to the growth of lychee trees. Wind protection is critical for good growth and fruit production. An ideal orchard site has long, hot days in summer (82°F, 28°C), adequate rainfall (around 63 inches, 1600 mm), and a cool, dry winter with day/night temperatures of 59/50°F (15/10°C). A dry period between October and February with lower temperatures (<59°F, <15°C) is necessary for prolific flower initiation on mature lychee trees and helps ensure a good crop.
In Hawaii, the cool winter season, generally lasting from October through April, is also the wet season in most places. Winter temperatures vary from year to year. Many locations in Hawaii are therefore less than ideal for reliable and consistent lychee yields. For commercial production, site selection can strongly influence profitability. Winter temperature cannot be controlled except by site selection for the general climate of the region or a suitable microclimate. Some degree of climate control affecting lychee flowering can be obtained by selecting a dry site with irrigation that can be withheld to create a dry period.
Many lychee cultivars are known in various parts of the world, including 26 major and 40 minor cultivars identified in Guangdong, China, 33 cultivars in India, and numerous local selections in Australia, Florida, Taiwan, Thailand, and Hawaii. Because lychee is one of the most environmentally sensitive fruit trees, improper selection of cultivars can result in erratic or no fruit production. Good growth in one location is not a guarantee of similar growth in another. For example, the Chinese cultivar 'No Mai Tsz' is one of the most recognized and preferred lychees in the world, but it is not suitable for production in Hawaii. Two mature 'No Mai Tsz' trees at CTAHR's Waiakea Research Station arboretum (Hilo) produced only two crops during the period 1986-1998.
In Hawaii, good performance is obtained with the cultivars 'Kaimana' and 'Groff', which were selected from 'Hak Ip' seedlings by CTAHR horticulturists. They require less chilling for flower initiation than traditional Chinese lychee cultivars. 'Kaimana' has proven to be a desirable cultivar because of its early harvest season (May-June), good fruit qualities, and large fruit size. Other lychee cultivars that are being grown in Hawaii are 'Souey Tung', 'Hak Ip', 'Tai So', 'Brewster', and 'Bosworth 3'.
Most of the many known lychee cultivars do not bear regularly or well under Hawaii's conditions. Lychee cultivars presently recommended for Hawaii are 'Groff', 'Kaimana', and 'Kwai Mi'. 'Groff' and 'Kaimana' are seedling selections originating in Hawaii. 'Kwai Mi' is an ancient and important Chinese cultivar.
'Kwai Mi' is a tall, upright, vigorous cultivar that does not bear regularly in Hawaii but can bear heavily in good years. It usually matures in May-June, producing large clusters of bright red fruits that average about 30 to a pound.
'Groff', developed from a 'Hak Ip' seedling, is an upright tree of medium vigor that bears somewhat regularly and is often late maturing (late August through September). Its fruits are dull red and small, 38- 42 to a pound, and a high percentage have abortive seeds.
'Kaimana', also a 'Hak Ip' seedling, is a medium-sized, compact, rounded tree that usually matures fruit from mid- June through July. Like 'Groff', it is considered good- bearing compared with most other cultivars in Hawaii. Its fruits are large, deep red, and 15-20 to a pound, with seeds that are not large in relation to the amount of flesh.
Lychee propagation from seed is unsatisfactory because cultivars do not reproduce true from seed. Seedling trees often take 10 years or more to come into bearing.
Lychee seeds are short-lived, losing viability after a few days, and are best planted fresh from the fruit. They should not be refrigerated, because this rapidly destroys viability.
The most common method of propagating lychee is air-layering, a technique for inducing a branch to form roots while still attached to the tree, after which it is removed and planted. Air-layering is done when leaves of the previous growth flush have matured. Air-layered trees usually take three to five years from planting to become established and begin bearing.
Lychee is most commonly propagated by air-layering. The procedure is as follows:
Containers with newly transplanted air-layered plants should be placed in a shaded area for about two weeks with a lightweight plastic bag placed over the plant to retain humidity until the plant begins to put out new growth. Later on, the plants can be gradually exposed to full sun to "harden." Transplanting to the field is best done during a rainy season, but if this is not possible, the plants should be watered every two to three days until well established. The trunk and rooted area should not be buried more than 1-2 inches (2.5-5 cm) below the level of the soil in the container. Removing about half of the leaves at the time of planting in the container and again when transplanting to the ground will prevent excessive moisture loss.
Lychee can also be propagated by grafting. For the introduction of new lychee cultivars to Hawaii, scion wood is easier to collect and transport than rooted air-layers and carries a lower quarantine risk of harboring pests and diseases.
Lychee can be grafted using the following modified top-wedge method developed at the USDA/ ARS National Clonal Germplasm Repository in Hilo:
Well grown lychee seedlings can be successfully patch-budded when the bark slips readily. Although not often used with lychee, budding is an excellent method that produces trees with better root systems than air-layering. Seedling root stocks for budding should be 1/3-1/2 inch (0.9-1.3 cm) in diameter.
Lychee is adaptable over a wide range of soil types, from heavy clays to a'a lavas, and tolerates wet soils to some degree. Coral sands are the least desirable soil type. Acidic soils from pH 5.0 to pH 6.5 are preferable.
Field preparation varies with local conditions. Measures to improve water movement into and through the soil may include breaking up compacted soil and hardpan by cultivation. Contouring the site can manage runoff and reduce ponding. Soil erosion can be controlled by contouring and establishing protective ground covers. Organic soil amendments (compost, manure) can improve the soil's capacity to hold water and nutrients. Applications of other soil amendments (such as lime and phosphorus) should be based on soil analysis recommendations. Windbreaks of trees suited to the site should be established well in advance of planting.
A planting distance of 18 x 18 feet (6 x 6 m) is recommended for upright cultivars such as 'Bosworth 3'. For 'Kaimana', a spacing of 24 x 24 ft (8 x 8 m) is recommended if annual pruning is practiced to control tree size. For more vigorous cultivars such as 'Tai So' and 'Brewster', a 24 x 36 ft (8 x 12 m) spacing is recommended.
Closer spacings, e.g., 23 ft (7 m) between trees, have been tried elsewhere, but this requires periodic pruning to control tree size. Temporary trees can be included in the centers with the idea of increasing early fruit production. These extra trees should be (but seldom are) removed before serious crowding occurs. Trees in house lots should be planted 25-30 ft (7.6-9 m) away from any building, large tree, or other obstruction. One lychee tree fully developed and symmetrical is better than two or more trees crowded together, competing for space and sunlight.
Air-layered plants 6-12 months old that have been sun-hardened can be transplanted to the field when there is adequate soil moisture. Handle the young lychee plants carefully to avoid breaking their extremely brittle roots. The transplanted tree will require about a year to become well established in the field, and adequate wind protection during this period is important. A single-tree wind shelter can be made by covering the sides of a cylinder of 52-inch hog-wire fencing 36 inches in diameter (130 x 90 cm) with 40-50 percent shade cloth. These netted cylinders also shield the plant from rose beetle damage.
Severe deficiency of soil phosphorus (P) should be corrected before planting by thoroughly mixing P fertilizer with the soil. Lime should be similarly incorporated to bring soil pH above 5.0. Surface applications of lime and P are not as effective as those that are tilled in. Dolomite can be substituted for part of the lime to provide magnesium. At transplanting, mix into the soil in the planting hole 4 oz (113 g) of triple super phosphate (0-46-0) plus 4 oz of a complete fertilizer (containing nitrogen [N], phosphoric acid [P2O5], and potash [K20]) in a 1-1-1 or 1-2-1 ratio.
For young trees up to three or four years of age, apply a complete fertilizer beginning after the hardening of the first growth flush after transplanting. Subsequent applications should be made after hardening of each succeeding flush, or every two to four months. Apply a total of about 1 lb (454 g) during Year 1, 11/2 lb (680 g) during Year 2, 21/2 lb (1135 g) during Year 3, and 4 lb (1816 g) during Year 4. The fertilizer should be spread evenly around the tree at least 1 ft (30 cm) from the trunk. Stop applying fertilizer in the spring of the third or fourth year, when the tree is large enough to bear a crop the next year.
Apply fertilizer to bearing trees immediately after fruit harvest. If rainfall is limited, apply irrigation water at that time to promote a vigorous flush. Bearing trees need less P than developing trees, so a fertilizer formulation such as 10-5-20 is appropriate. Excessive amounts of available N during the winter will favor untimely vegetative flushes; thus, N application levels should be calculated so that the N is depleted before a rest period prior to flowering occurs.
After fruit set, when the fruits are pea-sized, a supplemental application of 10-5-20 or 10-5-40 will provide adequate potassium for fruit development. This application should be light, because too much N at the time of fruit ripening may cause fruits to crack during rainy periods.
Amounts of fertilizer applied to bearing trees vary depending on tree condition and location. With many fruit trees, a general rule is to apply annually 1 lb (454 g) of fertilizer for each inch of trunk diameter measured at a height 4 -5 ft (1.2-1.5 m) from the ground. This rule may be difficult to use with lychee cultivars that have low branches. An alternative method is to apply 3/4 lb (340 g) of fertilizer for every year of tree age, reaching the maximum application level around Years 10 to 12. Organic soil amendments and fertilizers are useful to promote tree establishment but should be used with caution on bearing trees. Organic N is released more slowly than most chemical fertilizer N, and it may be more difficult to manage the time of availability and depletion of N from mulches and manures.
Australian Fertilizer Plan
During the first four years after planting, fertilizers should be applied generously to promote canopy development. A schedule developed in Australia is given below.
Fertilizer should be spread from the leaf drip line to no closer than 8 inches (20 cm) from the trunk. Micronutrients may be applied as foliar sprays in summer and fall. Boron and iron should be applied to mature summer and fall growth. Zinc, copper, and manganese should be applied to expanding summer and fall flushes.
Under ideal growing conditions, young trees produce five or more vegetative flushes each year. Training and shaping trees should be done during the first 3-4 years based on the growth habits of the cultivar and the environmental conditions.
For cultivars with a spreading canopy, such as 'Kaimana', open-center pruning is recommended. Three to four evenly spaced laterals with sufficiently wide (>30°) branching angles are retained about 20 inches (50 cm) above ground to form the main branches of the canopy. Very light thinning is done thereafter to remove low-hanging, tangled, weak, diseased, or dead branches. In Sichuan, China, the point of branching for the main frame can be as low as 4 inches (10 cm) above ground. This training system is reported to encourage early fruiting and low canopy height.
In Chiang Rai, Thailand, a lychee cultivar with vigorous vegetative growth, similar to 'Tai So', is trained with a central-leader system. A main stem is retained, with lateral branches evenly spaced on the main trunk at different heights to form an upright canopy. These trees are topped and maintained at about 15-21 ft (5-7 m), and the inner canopy is heavily thinned to ensure good light and air penetration. Only two or three new shoots per branch from the summer-fall flushes are retained for fruit production. Despite the upright style of pruning, harvesting is relatively simple, because the long-limbed branches are bent downward by the weight of the fruit clusters. Pruning at harvest is important: 6- 8 inches (15-20 cm) of each branch is removed along with the fruit. The harvest pruning and a biannual topping allows management of tree height and shape at the desired level.
Once an orchard is established, management practices such as pruning, girdling, root pruning, and regulating the supply of irrigation and nutrients are means to synchronize and/or suppress vegetative growth and facilitate fruit production. Lychee flowering and fruit set can be managed easier in light soils, which facilitate drought stress when withholding irrigation.
Girdling, also called ring-barking, is sometimes done to check growth and to promote increased flowering. The utility and efficacy of this practice are poorly documented for the lychee cultivars commonly grown in Hawaii. A pruning saw cut the width of the saw blade is made in the bark around the branch or trunk. The cut should form a complete ring and extend through (but not far beyond) the thin, white cambium layer beneath the bark. Girdling is preferably done in early September in Hawaii. Different branches are sometimes girdled in successive years to avoid damaging the tree.
Propping or bracing branches is advisable when heavy crops occur on trees with weak, sharp-angled crotches.
Pruning at harvest
Traditional harvesting practice has been to remove no more than two pairs of leaves with a fruit cluster. The zone of compacted nodes located above the fruit clusters, known as the "dragon head" in Chinese literature, was believed to contain fruiting branches for the following season.
Observations of 'Kaimana' in Hawaii revealed that the "dragon head" node produced new shoots about 6-8 weeks after harvest. These multiple branches were short, slender, and had poor vigor. If the "dragon head" node was removed during harvest along with 6-12 inches (15- 30 cm) of stem above the cluster, the new growth emerged approximately four weeks later and the number of shoots produced per node was less, but these shoots were longer and more vigorous.
In Taiwan, up to 24 inches (60 cm) of the branch is removed from 'Yu Ho Pau' at harvest to ensure vigorous vegetative flushes. Similar treatment of 'Hwai Lai' in China resulted in increased production over the traditional pruning method. The effect of pruning on production varies among cultivars. 'Yok Ho Pau' was reported to have a good yield with harvest pruning, while 'Hak Ip', 'Sam Yu Hung', and 'Sah Keng' had reduced yield after the same treatment.
In Australia, the most effective method to prevent untimely vegetative growth is to maintain leaf N content at 1.75-1.85 percent during the critical 4-6-week period before flower initiation. Maintaining low leaf N levels can be achieved by applying N fertilizer only after panicle emergence and fruit set and at no other time during the growing season. This method has proven effective even in areas with heavy rainfall.
For bearing trees of early-season cultivars (May-June harvest) such as 'Kaimana', it is desirable to induce two vegetative flushes after harvest, one in June-July and a second in August-September. To promote these two flushes, one-half of the fertilizer allocated for the year should be applied with irrigation immediately after harvest. The balance of the year's fertilizer should be applied in two equal parts, one in spring during flower panicle elongation and the second in early summer when fruits reach pea size.
For bearing trees of late-season cultivars (July-August harvest) such as 'Bosworth-3' and 'Groff', a single vegetative flush is promoted after harvest. One-third of the fertilizer allocated for the year should be applied two weeks before harvest. The remaining two-thirds of the fertilizer should be applied in two equal parts, one in spring during flower panicle elongation and the second when fruits reach pea size. The first application, before harvest, ensures sufficient time for the vegetative growth to mature before winter; the second, smaller application avoids high residual leaf N levels, which may inhibit flower induction.
For bearing trees in areas with deep soil and high rainfall, the allocation of fertilizer should be applied in two equal parts, one during spring flower panicle elongation and the other when fruits reach pea size. N-containing fertilizer should not be applied after harvest.
Suggested management procedure for 'Kaimana' lychee in Hawaii
The following practices to ensure fruit production worked reasonably well with 'Kaimana' in the Hilo area, which has high rainfall and highly weathered lava soils. Results may vary in locations with different soil types and microclimates. Use this as a general guide for bearing trees with May-June harvest, and customize your own management plan for lychee at your location.
New growth flushes occur several times a year. Under suitable conditions, one of these flushes, usually in the late winter months after the first of the year, may develop into a flowering flush. Increases in flowering and fruit set occur when there is a growth check caused by dry and/or cool weather after shoots of the previous growth flush have matured. Flowering and fruiting are usually poor whenever an adequate period or combination of cool or dry weather fails to occur. Favorable conditions for flowering and fruiting do not occur every year in Hawaii, or in any predictable sequence or pattern. When favorable conditions do occur, flowering takes place between February and April. Fruit matures three to five months after flowering.
The best climates for growing lychee have a warm, wet spring and summer followed by a cool, dry fall and winter. Ideal conditions for lychee production occur in subtropical Guangdong and Fujian, China, where the trees are planted along dikes and stream banks as well as in orchard blocks in frost-free, lowland areas. Temperatures drop below 50°F (10°C) in January and rise above 90°F (>32°C) in the summer. The rainfall averages about 65 inches (165 cm) per year, with 80 percent received between March and September.
Under less-than-ideal conditions, yields are usually variable and erratic. This is often the case in Hawaii. Excessively wet weather during October, November, and December initiates vegetative flushing when the trees should be undergoing a rest period, and these flushes use stored carbohydrate that is preferably reserved for flowering and fruiting. Breaking off late-flushing vegetative terminals may inhibit vegetative growth and result in better flowering. Warm, humid winter weather also results in poor fruiting. Rain and wind during flowering interfere with pollination and increase flower drop. Lack of rain, or low humidity, after flowering (between February and May) decreases fruit set. Strong winds during fruit development also reduce yields. Weather conditions different from these and more like those of Guangdong and Fujian, China, are conducive to better fruiting behavior.
Many of the cultivars imported from China seldom if ever fruit in Hawaii, regardless of weather conditions. As a consequence, they should not be planted except in cultivar collections. Examples of cultivarrs with this history are 'Kwa Luk', 'No Mai Tsze', and 'Heung Lai'.
Fruits are harvested after their skins turn red. Green fruits do not ripen satisfactorily after removal from the tree. In Hawaii, early cultivars are harvested in May and June, late cultivars from mid-July through September. Fruits are removed from the tree by cutting or breaking the branch off just above the panicle bearing the fruits.
After harvest, fruit skin color turns reddish-brown in a few days if not refrigerated. Refrigeration at 32-40°F (0-5°C) and storage in plastic bags can prolong fresh fruit color and flavor for about two weeks. Fruit to be stored in refrigeration should be broken off the panicle, leaving a bit of stem attached. If the fruit is pulled from the stem, the skin may break, resulting in dehydration and, possibly, spoilage. Lychees may be quick-frozen, dried, or canned.
Under current (1990) regulations, fresh lychee fruits may not be exported from Hawaii to the U.S. Mainland or Japan. Frozen lychee fruits may be taken to the U.S. Mainland after inspection by Hawaii plant quarantine authorities.
Litchi mite, erinose mite (Eriophyes litchii)
Green scale (Coccus viridis)
Hemispherical scale (Saissetia coffeae)
White litchi scale (Pseudaulacaspis major)
Chinese rose beetle (Adoretus sinicus)
Litchi fruit moth (Cryptophlebia ombrodelta)
Koa seedworm, macadmaia husk borer (Cryptophlebia illepida)
Anthurium thrips (Chaetanaphothrips orchidii)
Redbanded thrips (Selenothrips rubrocintus)
Black twig borer (Xylosandrus compactus)
A twig borer (Xylosandrus crassiusculus)
An ambrosia beetle (Xyleborus fornicatus)
A spider mite (Oligonychus biharensis)
The erinose mite is a tiny pest (1/200 inch [0.13 mm] long) that cannot be seen without a microscope, but its damage on lychee is distinctive and often extensive. Leaflets become curled and distorted and have a velvety brown appearance. The mites begin their attack on new leaves at the onset of growth flushes. Early indications of their damage are small, wart like swellings about 1/16 inch (1.6 mm) in diameter on the upper surface of leaflets and light yellow spots on the corresponding sites on the lower surface.
Erinose mite damage seldom kills lychee trees but is unsightly. Yield loss as a result of erinose mite damage has not been demonstrated.
Besides the erinose mite, the most common insect pests of lychee are the Cryptophlebia spp. (damaging fruits) and thrips and scales (affecting foliage).
No serious disease problems are presently found on lychees in Hawaii.
Red-vented bulbul (Pycnonotus cafer)
Red-whiskered bulbul (P. jocosus)
Mejiro, Japanese white-eye (Zosterops japonicus)
Mejiro and bulbuls are serious pests of both immature and ripe fruit. These and most other birds are protected by state and in some cases federal regulations, and they may not be trapped or killed without a permit. Shiny objects and streamers are sometimes used to repel birds, usually with only temporary success. Bird netting can be used to protect fruiting branches. Bulbuls are presently (1990) established only on Oahu, but they have been seen on the neighbor islands.
Sightings of bulbuls beyond Oahu should be reported to the local office of the Department of Land and Natural Resources, the Hawaii Department of Agriculture, or the Cooperative Extension Service.