By: Mary Ellen Ellis
Lychee trees are fun to grow in tropical gardens because they provide both a nice landscape focus and a harvest of tasty fruits. Figure out what is causing fruit drop and take steps to ensure a better crop.
If your fruit is dropping early, there could be several reasons. Lychee trees generally set more fruits than it is possible to hold, so some dropping can be the result of natural attrition.
Stress can increase natural fruit drop in lychee, and stress may be increased by drought, temperatures that are colder than normal, or nutrient deficiencies. Lychee is notoriously ready to drop fruit early, so being careful to minimize stress is important.
Other reasons for lychee tree dropping fruit at a high rate include infections and pests. There are several pests that may attack your tree and contribute to more fruit drop: lychee stink bug, fruitspotting bugs, erinose mites, and several types of moths and fruit flies.
Downy blight disease causes brown lesions on fruit and early dropping. Birds can also cause fruit to drop early.
First, be sure that your tree is getting everything it needs to reduce stress. These trees require a lot of water, plenty of sun, a slightly acidic soil, and an occasional general fertilizer to be their healthiest. The right conditions will both discourage early fruit drop and help trees better resist infections and diseases.
You can also look out for signs of disease or pests on your trees and take steps to manage them early to minimize the damage and fruit drop. Check with your local nursery to find out what sprays are best for your fruit tree.
Another strategy for preserving more of the fruit on your lychee is to bag the fruits. Netting keeps birds off trees but not insects. Bagging the fruit protects it from both. To bag a lychee tree, use any kind of paper bag. Place the bags around individual panicles about six weeks after the tree has fully bloomed (the fruits will be about ¾ of an inch or 2 cm. long). You can secure the bag any way that is easiest, but simply stapling or tying it around the stem is adequate.
Research has found that bagging a lychee tree is well worth the effort and the cost of bags, as it does increase fruit yield significantly. As a bonus, you won’t need to net the whole tree or use pesticides to deter insects and birds.
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As you look out over your garden, you notice that the lychee's pinkish-red fruits contrast nicely against the tree's evergreen leaves. Native to southeastern China, the lychee tree (Litchi chinensis) is hardy in U.S. Department of Agriculture plant hardiness zones 10 and 11. Lychee trees cannot tolerate any frost, preferring a location next to a sunny, wind-sheltered, south-facing wall that produces a warm microclimate. The slow-growing tree produces ping pong ball-sized fruits once peeled, they reveal a white, jelly-like, sweet interior and large seed.
Providing trees with special care is effective only if the plant is already growing in optimal conditions. Lychee trees grow best in areas of the home garden that offer full sunlight, which is particularly significant for healthy flowering and fruit growth. These evergreens thrive in most soil types, provided that soil is moist and well-drained. The ideal pH range is 5.0 to 7.5, as alkalinity may result in an iron deficiency. Lychee trees grow most successfully in U.S. Department of Agriculture plant hardiness zones 10a through 11.
|Plate XXXII: LYCHEE, Litchi chinensis|
The lychee is native to low elevations of the provinces of Kwangtung and Fukien in southern China, where it flourishes especially along rivers and near the seacoast. It has a long and illustrious history having been praised and pictured in Chinese literature from the earliest known record in 1059 A.D. Cultivation spread over the years through neighboring areas of southeastern Asia and offshore islands. Late in the 17th Century, it was carried to Burma and, 100 years later, to India. It arrived in the West Indies in 1775, was being planted in greenhouses in England and France early in the 19th Century, and Europeans took it to the East Indies. It reached Hawaii in 1873, and Florida in 1883, and was conveyed from Florida to California in 1897. It first fruited at Santa Barbara in 1914. In the 1920's, China's annual crop was 30 million lbs (13.6 million kg). In 1937 (before WW II) the crop of Fukien Province alone was over 35 million lbs (16 million kg). In time, India became second to China in lychee production, total plantings covering about 30,000 acres (12,500 ha). There are also extensive plantings in Pakistan, Bangladesh, Burma, former Indochina, Taiwan, Japan, the Philippines, Queensland, Madagascar, Brazil and South Africa. Lychees are grown mostly in dooryards from northern Queensland to New South Wales, but commercial orchards have been established in the past 20 years, some consisting of 5,000 trees.
Madagascar began experimental refrigerated shipments of lychees to France in 1960. It is recorded that there were 2 trees about 6 years old in Natal, South Africa, in 1875. Others were introduced from Mauritius in 1876. Layers from these latter trees were distributed by the Durban Botanical Gardens and lychee-growing expanded steadily until in 1947 there were 5,000 bearing trees on one estate and 5,000 newly planted on another property, a total of 40,000 in all.
In Hawaii, there are many dooryard trees but commercial plantings are small. The fruit appears on local markets and small quantities are exported to the mainland but the lychee is too undependable to be classed as a crop of serious economic potential there. Rather, it is regarded as a combination ornamental and fruit tree.
There are only a few scattered trees in the West Indies and Central America apart from some groves in Cuba, Honduras and Guatemala. In California, the lychee will grow and fruit only in protected locations and the climate is generally too dry for it. There are a few very old trees and one small commercial grove. In the early 1960's, interest in this crop was renewed and some new plantings were being made on irrigated land.
At first it was believed that the lychee was not well suited to Florida because of the lack of winter dormancy, exposing successive flushes of tender new growth to the occasional periods of low temperature from December to March. The earliest plantings at Sanford and Oviedo were killed by severe freezes. A step forward came with the importation of young lychee trees from Fukien, China, by the Rev. W.M. Brewster between 1903 and 1906. This cultivar, the centuries-old 'Chen-Tze' or 'Royal Chen Purple', renamed 'Brewster' in Florida, from the northern limit of the lychee-growing area in China, withstands light frost and proved to be very successful in the Lake Placid areathe "Ridge" section of Central Florida.
Layered trees were available from Reasoner's Royal Palm Nurseries in the early 1920's, and the Reasoner's and the U.S. Department of Agriculture made many new introductions for trial. But there were no large plantings until an improved method of propagation was developed by Col. William R. Grove who became acquainted with the lychee during military service in the Orient, retired from the Army, made his home at Laurel (14 miles south of Sarasota, Florida) and was encouraged by knowledgeable Prof. G. Weidman Groff, who had spent 20 years at Canton Christian College. Col. Grove made arrangements to air-layer hundreds of branches on some of the old, flourishing 'Brewster' trees in Sebring and Babson Park and thus acquired the stock to establish his lychee grove. He planted the first tree in 1938, and by 1940 was selling lychee plants and promoting the lychee as a commercial crop. Many small orchards were planted from Merritt's Island to Homestead and the Florida Lychee Growers' Association was founded in 1952, especially to organize cooperative marketing. The spelling "lychee" was officially adopted by the association upon the strong recommendation of Professor Groff.
In 1960, over 6,000 lbs (2,720 kg) were shipped to New York, 4,000 lbs (1,814 kg) to California, nearly 6,000 lbs (2,720 kg) to Canada, and 3,900 lbs (1, 769 kg) were consumed in Florida, though this was far from a record year. The commercial lychee crop in Florida has fluctuated with weather conditions, being affected not only by freezes but also by drought and strong winds. Production was greatly reduced in 1959, to a lesser extent in 1963, fell drastically in 1965, reached a high of 50,770 lbs (22,727 kg) in 1970, and a low of 7,200 lbs (3,273 kg) in 1974. Some growers lost up to 70% of their crop because of severe cold in the winter of 1979-80. Of course, there are many bearing trees in home gardens that are not represented in production figures. The fruit from these trees may be merely for household consumption or may be purchased at the site by Chinese grocers or restaurant operators, or sold at roadside stands.
Though the Florida lychee industry is small, mainly because of weather hazards, irregular bearing and labor of hand-harvesting, it has attracted much attention to the crop and has contributed to the dissemination of planting material to other areas of the Western Hemisphere. Escalating land values will probably limit the expansion of lychee plantings in this rapidly developing state. Another limiting factor is that much land suitable for lychee culture is already devoted to citrus groves.
Professor Groff, in his book, The lychee and the lungan, tells us that the production of superior types of lychee is a matter of great family pride and local rivalry in China, where the fruit is esteemed as no other. In 1492, a list of 40 lychee varieties, mostly named for families, was published in the Annals of Fukien. In the Kwang provinces there were 22 types, 30 were listed in the Annals of Kwangtung, and 70 were tallied as varieties of Ling Nam. The Chinese claim that the lychee is highly variable under different cultural and soil conditions. Professor Groff concluded that one could catalog 40 or 50 varieties as recognized in Kwangtung, but there were only 15 distinct, widely-known and commercial varieties grown in that province, half of them marketed in season in the City of Canton. Some of these are classed as "mountain" types the majority are "water types" (grown in low, well-irrigated land). There is a special distinction between the kinds of lychee that leak juice when the skin is broken and those that retain the juice within the flesh. The latter are called "dry- and -clean" and are highly prized. There is much variation in form (round, egg-shaped or heart-shaped), skin color and texture, the fragrance and flavor and even the color, of the flesh and the amount of "rag" in the seed cavity and, of prime importance, the size and form of the seed.
The following are the 15 cultivars recognized by Professor Groff:
'No Mai Tsze' , or 'No mi ts 'z' (glutinous rice) is the leading variety in China large, red, "dry-and-clean" seeds often small and shriveled. It is one of the best for drying, and is late in season. It does best when grafted onto the 'Mountain' lychee.
'Kwa Iuk' or 'Kua lu' (hanging green) is a famous lychee large, red with a green tip and a typical green line "dry-and-clean" of outstanding flavor and fragrance. It was, in olden times, a special fruit for presentation to high officials and other persons in positions of honor. Professor Groff was given a single fruit in a little red box!
'Kwai mi' or 'Kuei Wei', (cinnamon flavor) which came to be called 'Mauritius' is smaller, heart-shaped, with rough red skin tinged with green on the shoulders and usually having a thin line running around the fruit. The seed is small and the flesh very sweet and fragrant. The branches of the tree curve upward at the tips and the leaflets curl inward from the midrib.
'Hsiang li' , or 'Heung lai' (fragrant lychee) is home by a tree with distinctive erect habit having upward-pointing leaves. The fruit is small, very rough and prickly, deep-red, with the smallest seeds of all, and the flesh is of superior flavor and fragrance. It is late in season. Those grown in Sin Hsing are better than those grown in other locations.
'Hsi Chio tsu', or 'Sai kok tsz' (rhinoceros horn) is borne by a large-growing tree. The fruit is large, rough, broad at the base and narrow at the apex has somewhat tough and fibrous, but fragrant, sweet, flesh. It ripens early.
'Hak ip' , or 'Hei yeh', (black leaf) is borne by a densely-branched tree with large, pointed, slightly curled, dark-green leaflets. The fruit is medium-red, sometimes with green tinges, broad-shouldered, with thin, soft skin and the flesh, occasionally pinkish, is crisp and sweet. This is rated as "one of the best 'water' lychees."
'Fei tsu hsiao', or 'Fi tsz siu' (imperial concubine's laugh, or smile) is large, amber-colored, thin-skinned, with very sweet, very fragrant flesh. Seeds vary from large to very small. It ripens early.
'T' ang po' , or 'T' ong pok' (pond embankment) is from a small-leaved tree. The fruit is small, red, rough, with thin, juicy acid flesh and very little rag. It is a very early variety.
'Sheung shu wai' or'Shang hou huai', (President of a Board's embrace) is borne on a small-leaved tree. The fruit is large, rounded, red, with many dark spots. It has sweet flesh with little scent and the seed size is variable. It is rather late in season.
'Ch'u ma lsu', or 'Chu ma lsz' (China grass fiber) has distinctive, lush foliage. The leaves are large, overlapping, with long petioles. The fruits are large with prominent shoulders and rough skin, deep red inside. While very fragrant, the flesh is of inferior flavor and clings to the seed which varies from large to small.
'Ta tsao' , or 'Tai tso' (large crop) is widely grown around Canton somewhat egg-shaped skin rough, bright-red with many small, dense dots flesh firm, crisp, sweet, faintly streaked with yellow near the large seed. The juice leaks when the skin is broken. The fruit ripens early.
'Huai chih', or 'Wai chi' (the Wai River lychee) has medium-sized, blunt leaves. The fruit is round with medium-smooth skin, a rich red outside, pink inside and leaking juice. This is not a high class variety but the most commonly grown, high yielding, and late in season.
'San yueh hung', or 'Sam ut hung' (third month red), also called 'Ma yuen', 'Ma un', 'Tsao kuo', 'Tso kwo', 'Tsao li', or 'Tsoli' (early lychee) is grown along dykes. The branches are brittle and break readily the leaves are long, pointed, and thick. The fruit is very large, with red, thick, tough skin and thick, medium-sweet flesh with much rag. The seeds are long but aborted. This variety is popular mainly because it comes into season very early.
'Pai la li chih', or 'Pak lap lai chi' (white wax lychee), also called 'Po le tzu', or 'Pak lik tsz (white fragrant plant), is large, pink, rough, with pinkish, fibrous, not very sweet flesh and large seeds. It ripens very late, after 'Huai chih'.
'Shan chi', or 'Shan chih' (mountain lychee), also called 'Suan chih', or 'Sun chi' (sour lychee) grows wild in the hills and is often planted as a rootstock for better varieties. The tree is of erect habit with erect twigs and large, pointed, short-petioled leaves. The fruit is bright-red, elongated, very rough, with thin flesh, acid flavor and large seed.
'T'im ngam', or 'T'ien yeh' (sweet cliff) is a common variety of lychee which Professor Groff reported to be quite widely grown in Kwantung, but not really on a commercial basis.
In his book, The Litchi, Dr. Lal Behari Singh wrote that Bihar is the center of lychee culture in India, producing 33 selected varieties classified into 15 groups. His extremely detailed descriptions of the 10 cultivars recommended for large-scale cultivation I have abbreviated (with a few bracketed additions from other sources):
'Early Seedless' , or 'Early Bedana'. Fruit 1 1/3 in (3.4 cm) long, heart-shaped to oval rough, red, with green interspaces skin firm and leathery flesh [ivory] to white, soft, sweet seed shrunken, like a dog's tooth. Of good quality. The tree bears a moderate crop, early in season.
'Rose-scented' . Fruit 1 1/4 in (3.2 cm) long rounded-heart-shaped slightly rough, purplish-rose, slightly firm skin flesh gray-white, soft, very sweet. Seed round-ovate, fully developed. Of good quality. [Tree bears a moderate crop] in midseason.
'Early Large Red' . Fruit slightly more than 1 1/3 in (3.4 cm) long, usually obliquely heart-shaped crimson [to carmine], with green interspaces very rough skin very firm and leathery, adhering slightly to the flesh. Flesh grayish-white, firm, sweet and flavorful. Of very good quality. [Tree is a moderate bearer], early in season.
'Dehra Dun', [or 'Dehra Dhun']. Fruit less than 1 1/2 in (4 cm) long obliquely heart-shaped to conical a blend of red and orange-red skin rough, leathery flesh gray-white, soft, of good, sweet flavor. Seed often shrunken, occasionally very small. Of good quality midseason. [This is grown extensively in Uttar Pradesh and is the most satisfactory lychee in Pakistan.]
'Late Long Red', or 'Muzaffarpur'. Fruit less than 1 1/2 in (4 cm) long usually oblong-conical dark-red with greenish interspaces skin rough, firm and leathery, slightly adhering to the flesh flesh grayish-white, soft, of good, sweet flavor. Seed cylindrical, fully developed. Of good quality. [Tree is a heavy bearer], late in season.
'Pyazi'. Fruit 1 1/3 in (3.4 cm) long oblong-conical to heart-shaped a blend of orange and orange-red, with yellowish-red, not very prominent, tubercles. Skin leathery, adhering flesh gray-white, firm, slightly sweet, with flavor reminiscent of "boiled onion". Seed cylindrical, fully developed. Of poor quality. Early in season.
'Extra Early Green'. Fruit 1 1/4 in (3.2 cm) long mostly heart-shaped, rarely rounded or oblong yellowish-red with green interspaces skin slightly rough, leathery, slightly adhering flesh creamy-white, [firm, of good, slightly acid flavor] seed oblong, cylindrical or flat. Of indifferent quality. Very early in season.
'Kalkattia', ['Calcuttia', or 'Calcutta']. Fruit 1 1/2 in (4 cm) long oblong or lopsided rose-red with darker tubercles skin very rough, leathery, slightly adhering flesh grayish ivory, firm, of very sweet, good flavor. Seed oblong or concave. Of very good quality. [A heavy bearer withstands hot winds]. Very late in season.
'Gulabi'. Fruit 1 1/3 in (3.4 cm) long heart-shaped, oval or oblong pink-red to carmine with orange-red tubercles skin very rough, leathery, non-adherent flesh gray-white, firm, of good subacid flavor seed oblong-cylindrical, fully developed. Of very good quality. Late in season.
'Late Seedless' , or 'Late Bedana'. Fruit less than 1 3/8 in (3.65 cm) long mainly conical, rarely ovate orange-red to carmine with blackish-brown tubercles skin rough, firm, non-adherent flesh creamy-white, soft very sweet, of very good flavor except for slight bitterness near the seed. Seed slightly spindle-shaped, or like a dog's tooth underdeveloped. Of very good quality. [Tree bears heavily. Withstands hot winds.] Late in season.
There are numerous lychee orchards in the submontane region of the Punjab. The leading variety is:
'Panjore common' . Fruit is large, heart-shaped, deep-orange to pink skin is rough, very thin, apt to split. Tree bears heavily and has the longest fruiting season-for an entire month beginning near the end of May. Six other varieties commonly grown there are: 'Rose-scented', 'Bhadwari', 'Seedless No. 1', 'Seedless No. 2', 'Dehra Dun', and 'Kalkattia'.
In South Africa, only one variety is produced commercially. It is the 'Kwai Mi' but it is locally called 'Mauritius' because nearly all of the trees are descendants of those brought in from that island. In South Africa, the fruit is of medium size, nearly round but slightly oval, reddish-brown. Flesh is firm, of good quality and usually contains a medium-sized seed, but certain fruits with broad, flat shoulders and shortened form tend to have "chicken-tongue" seeds.
There have been many other introductions into South Africa from China and India but most failed to survive. In 1928, 16 varieties from India were planted at Lowe's Orchards, Southport, Natal, but the records were lost and they remained unnamed. A Litchi Variety Orchard of 26 cultivars from India, China, Taiwan and elsewhere was established at the Subtropical Horticulture Research Station in Nelspruit. Tentative classifications grouped these into 3 distinct types'Kwai Mi' ['Mauritius'], 'Hak Ip' (of high quality and small seed but a shy bearer in the Low-veld), and the 'Madras', a heavy bearer of choice fruits, bright-red, very rough, and with large seeds, but very sweet, luscious flesh.
The first lychee introduced into Hawaii was the 'Kwai Mi', as was the second introduction several years later. The high quality of this variety (sometimes locally called 'Charlie Long') caused the lychee to become extremely popular and widely planted. The Hawaiian Agricultural Experiment Station imported 3 'Brewster' trees in 1907, and various efforts were made to bring other types from China but not all survived. A total of 16 varieties became well established in Hawaii, including 'Hak Ip' which has become second to 'Kwai Mi' in importance.
In 1942, the Agricultural Experiment Station set out a collection of 500 seedlings of 'Kwai Mi', 'Hak Ip' and 'Brewster' with a view to selecting the trees showing the best performance. One tree of outstanding character (a seedling of 'Hak Ip') was first designated H.A.E.S. Selection 1-18-3 and was given the name 'Groff' in 1953. It is a consistent bearer, late in season. The fruit is of medium size, dark rose-red with green or yellowish tinges on the apex of each tubercle. The flesh is white and firm there is no leaking juice the flavor is excellent, sweet and subacid most of the fruits have abortive, "chicken-tongue" seeds and, accordingly have 20% more flesh than if the seeds were fully developed.
'No Mai Tsze' has been growing in Hawaii for over 40 years but has produced very few fruits. 'Pat Po Heung' (eight precious fragrances), erroneously called 'Pat Po Hung' (eight precious red), somewhat resembles 'No Mai Tsze' but is smaller the skin is purplish-red, thin and pliable the juice leaks when the skin is broken the flesh is soft, juicy, sweet even when slightly unripe the seed varies from medium to large. The tree is slow-growing and of weak, spreading habit it bears well in Hawaii. Nevertheless, it is not commonly planted.
'Kaimana' , or 'Poamoho', an open-pollinated seedling of 'Hak Ip', developed by Dr. R.A. Hamilton at the Poamoho Experiment Station of the University of Hawaii, was released in 1982. The fruit resembled 'Kwai Mi' but is twice as large, deep-red, of high quality, and the tree is a regular bearer.
'Brewster' is large, conical or wedge-shaped, red, with soft flesh, more acid than that of 'Kwai mi', and the seeds are very often fully formed and large. The leaflets are flat with slightly recurved margins and taper to a sharp point.
There were many other introductions of seeds, seedlings, cuttings or air-layers into the United States, from 1902 to 1924, mostly from China also from India and Hawaii, and a few from Java, Cuba, and Trinidad and these were distributed to experimenters in Florida and California, and some to botanical gardens in other states, and to Cuba, Puerto Rico, Panama, Honduras, Costa Rica and Brazil. Many were killed by cold weather in California and Florida.
In 1908, the United States Department of Agriculture brought in 27 plants of 'Kwai mi'. At the same time, 20 plants of 'Hak Ip' were imported and these were sent to George B. Cellon in Miami in 1918. A tree of the 'Bedana' was introduced from India in 1913. In 1920, Professor Groff obtained seedlings of 'Shan Chi' (mountain lychee) from Kwantung Province, together with air-layers of 'Sheung shu wai', 'No mai ts 'z', and 'T' im ngam' (sweet cliff). The latter was found to bear more regularly than 'Brewster' but exhibited nutritional deficiencies in limestone soil.
Most of the various plants and rooted cuttings from them were distributed for trial the rest were kept in U.S. Department of Agriculture greenhouses in Maryland.
'Bengal' In 1929, the U.S. Department of Agriculture received a small lychee plant, supposedly a seedling of 'Rose-scented', from Calcutta. It was planted at the Plant Introduction Station in Miami and began bearing in 1940. The fruits resembled 'Brewster' but were more elongated, were home in large clusters, and the flesh was firm, not leaking juice when peeled. All the fruits had fully developed seeds but smaller in proportion to flesh than those of 'Brewster'. The habit of the tree is more spreading than that of 'Brewster' it has larger, more leathery, darker green leave's, and the bark is smoother and paler. The original tree and its air-layered progeny have shown no chlorosis on limestone in contrast to 'Brewster' trees growing nearby.
'Peerless' , believed to be a seedling of 'Brewster', originated at the Royal Palm Nursery at Oneco was transplanted to the T.R. Palmer Estate in Belleair where C.E. Ware noticed from 1936 to 1938 that it bore fruit of larger size, brighter color and higher percentage of abortive seed than 'Brewster'. In 1938, Ware air-layered and removed 200 branches, purchased the tree and moved it to his property in Clearwater. It resumed fruiting in 1940 and annual crops recorded to 1956 showed good productivity-averaging 383.4 lbs (174 kg) per year, and the rate of abortive seeds ranged from 62% to 85%. The 200 air-layers were planted out by Ware in 1942 and began bearing in 1946. Most of the fruits had fully developed seeds but the rate of abortive seeds increased year by year and in 1950 was 61% to 70%. The cultivar was named with the approval of the Florida Lychee Growers Association. Two seedling selections by Col. Grove, 'Yellow Red' and 'Late Globe', Prof. Groff believed to be natural hybrids of 'Brewster' ´ 'Mountain'.
In northern Queensland, 'Kwai Mi' is the earliest cultivar grown, and about 10% of the fruits have "chicken tongue" seeds. 'Brewster' bears in mid-season and is important though the seed is nearly always fully formed and large. 'Hak Ip' is also midseason and large-seeded there. 'Bedana' is grown only in home gardens and the fruits have large seeds unlike the usual "chicken tongue" seeds of the fruits of this cultivar borne in India i
'Wai Chi' is late in season (December), has small, round fruits, basically yellow overlaid with red the seed is small and oval. The tree is very compact with upright branches, and prefers a cooler climate than that of coastal north Queensland where it does not fruit heavily. The leaflets are concave like those of 'Kwai Mi'.
A very similar, perhaps identical, cultivar called 'Hong Kong' is grown in South Queensland. 'No Mai' bears poorly in Queensland and seems better adapted to cooler areas.
There are 3 types of flowers appearing in irregular sequence or, at times, simultaneously, in the lychee inflorescence: a) male b) hermaphrodite, fruiting as female (about 30% of the total) c) hermaphrodite fruiting as male. The latter tend to possess the most viable pollen. Many of the flowers have defective pollen and this fact probably is the main cause of the abortive seeds and also the common problem of shedding of young fruits. The flowers require transfer of pollen by insects.
In India, L.B. Singh recorded 11 species of bees, flies, wasps and other insects as visiting lychee flowers for nectar. But honeybees, mostly Apis cerana indica, A. dorsata and A. florea, constitute 78% of the lychee-pollinating insects and they work the flowers for pollen and nectar from sunrise to sundown. A. cerana is the only hive bee and is essential in commercial orchards for maximum fruit production.
A 6-week survey in Florida revealed 27 species of lychee-flower visitors, representing 6 different insect Orders. Most abundant, morning and afternoon, was the secondary screw-worm fly (Callitroga macellaria), an undesirable pest. Next was the imported honeybee (Apis mellifera) seeking nectar daily but only during the morning and apparently not interested in the pollen. No wild bees were seen on the lychee flowers, though wild bees were found in large numbers collecting pollen in an adjacent fruit-tree planting a few weeks later. Third in order, but not abundant, was the soldier beetle (Chauliognathus marginatus). The rest of the insect visitors were present only in insignificant number. Maintenance of bee hives in Florida lychee groves is necessary to enhance fruit set and development. The fruits mature 2 months after flowering.
In India and Hawaii, there has been some interest in possible cross-breeding of the lychee and pollen storage tests have been conducted. Lychee pollen has remained viable at room temperature for 10 to 30 days in petri dishes for 3 to 5 months in desiccators 15 months at 32° F (0° C) and 25% relative humidity in desiccators and 31 months under deep-freeze, -9.4° F (-23° C). There is considerable variation in the germination rates of pollen from different cultivars. In India, 'Rose Scented' has shown mean viability of 61.99% compared with 42.52% in 'Khattl'.
Groff provided a clear view of the climatic requirements of the lychee. He said that it thrives best in regions "not subject to heavy frost but cool and dry enough in the winter months to provide a period of rest." In China and India, it is grown between 15° and 30° N. "The Canton delta . is crossed by the Tropic of Cancer and is a subtropical area of considerable range in climate. Great fluctuations of temperature are common throughout the fall and winter months. In the winter sudden rises of temperature will at times cause the lychee . to flush forth . new growth. This new growth is seldom subject to a freeze about Canton. On the higher elevations of the mountain regions which are subject to frost the lychee is seldom grown . . . The more hardy mountainous types of the lychee are very sour and those grown near salt water are said to be likewise. The lychee thrives best on the lower plains where the summer months are hot and wet and the winter months are dry and cool."
Heavy frosts will kill young trees but mature trees can withstand light frosts. Cold tolerance of the lychee is intermediate between that of the sweet orange on one hand and mango and avocado on the other. Location, land slope, and proximity to bodies of water can make a great difference in degree of damage by freezing weather. In the severe low temperature crisis during the winter of 1957-58, the effects ranged from minimal to total throughout central and southern Florida. A grove of 12-to 14-year-old trees south of Sanford was killed back nearly to the ground on Merritt Island trees of the same age were virtually undamaged, while a commercial mango planting was totally destroyed. L.B. Singh resists the common belief that the lychee needs winter cold spells that provide periods of temperature between 30° and 40° F (-1.11° and 4.44° C) because it does well in Mauritius where the temperature is never below 40° F (-1.11° C). However, lychee trees in Panama, Jamaica, and other tropical areas set fruit only occasionally or not at all.
Heavy rain or fog during the flowering period is detrimental, as are hot, dry, strong winds which cause shedding of flowers, also splitting of the fruit skin. Splitting occurs, too, during spells of alternating rain and hot, dry periods, especially on the sunny side of the tree. Spraying with Ethephon at 10 ppm reduced splitting in 'Early Large Red' in experiments in Nepal.
The lychee grows well on a wide range of soils. In China it is cultivated in sandy or clayey loam, "river mud", moist sandy clay, and even heavy clay. The pH should be between 6 and 7. If the soil is deficient in lime, this must be added. However, in an early experiment in a greenhouse in Washington, D.C., seedlings planted in acid soil showed superior growth and the roots had many nodules filled with mycorrhizal fungi. This caused some to speculate that inoculation might be desirable. Later, in Florida, profuse nodulation was observed on roots of lychee seedlings that had not been inoculated but merely grown in pots of sphagnum moss and given a well-balanced nutrient solution.
The lychee attains maximum growth and productivity on deep alluvial loam but flourishes in extreme southern Florida on oolitic limestone providing it is put in an adequate hole and irrigated in dry seasons.
The Chinese often plant the lychee on the banks of ponds and streams. In low, wet land, they dig ditches 10 to 15 ft (3-4.5 m) wide and 30 to 40 ft (9-12 m) apart, using the excavated soil to form raised beds on which they plant lychee trees, so that they have perfect drainage but the soil is always moist. Though the lychee has a high water requirement, it cannot stand water-logging. The water table should be at least 4 to 6 ft (1.2-1.8 m) below the surface and the underground water should be moving inasmuch as stagnant water induces root rot. The lychee can stand occasionally brief flooding better than citrus. It will not thrive under saline conditions.
Lychees do not reproduce faithfully from seed, and the choicest have abortive, not viable, seed. Furthermore, lychee seeds remain viable only 4 to 5 days, and seedling trees will not bear until they are 5 to 12, or even 25, years old. For these reasons, seeds are planted mostly for selection and breeding purposes or for rootstock.
Attempts to grow the lychee from cuttings have been generally discouraging, though 80% success has been claimed with spring cuttings in full sun, under constant mist and given weekly liquid nutrients. Ground-layering has been practiced to some extent. In China, air-layering (marcotting, or gootee) is the most popular means of propagation and has been practiced for ages. By their method, a branch of a chosen tree is girdled, allowed to callus for 1 to 2 days and then is enclosed in a ball of sticky mud mixed with chopped straw or dry leaves and wrapped with burlap. With frequent watering, roots develop in the mud and, in about 100 days, the branch is cut off, the ball of earth is increased to about 12 in (30 cm) in width, and the air-layer is kept in a sheltered nursery for a little over a year, then gradually exposed to full sun before it is set out in the orchard. Some air-layers are planted in large clay pots and grown as ornamentals.
The Chinese method of air-layering has many variations. In fact, 92 modifications have been recorded and experimented with in Hawaii. Inarching is also an ancient custom, selected cultivars being joined to 'Mountain' lychee rootstock.
In order to make air-layering less labor-intensive, to eliminate the watering, and also to produce portable, shippable layers, Colonel Grove, after much experimentation, developed the technique of packing the girdle with wet sphagnum moss and soil, wrapping it in moisture-proof clear plastic that permits exchange of air and gasses, and tightly securing it above and below. In about 6 weeks, sufficient roots are formed to permit detaching of the layer, removal of the plastic wrap, and planting in soil in nursery containers. It is possible to air-layer branches up to 4 in (10 cm) thick, and to take 200 to 300 layers from a large tree.
Studies in Mexico have led to the conclusion that, for maximum root formation, branches to be air-layered should not be less than 5/8 in (15 mm) in diameter, and, to avoid undue defoliation of the parent tree, should not exceed 3/4 in (20 mm). The branches, of any age, around the periphery of the canopy and exposed to the sun, make better air-layers with greater root development than branches taken from shaded positions on the tree. The application of growth regulators, at various rates, has shown no significant effect on root development in the Mexican experiments. In India, certain of the various auxins tried stimulated root formation, forced early maturity of the layers, but contributed to high mortality. South African horticulturists believe that tying the branch up so that it is nearly vertical induces vigorous rooting.
The new trees, with about half of the top trimmed off and supported by stakes, are kept in a shadehouse for 6 weeks before setting out. Improvements in Colonel Grove's system later included the use of constant mist in the shadehouse. Also, it was found that birds pecked at the young roots showing through the transparent wrapping, made holes in the plastic and caused dehydration. It became necessary to shield the air-layers with a cylinder of newspaper or aluminum foil. As time went on, some people switched to foil in place of plastic for wrapping the air-layers.
The air-layered trees will fruit in 2 to 5 years after planting, Professor Groff said that a lychee tree is not in its prime until it is 20 to 40 years old will continue bearing a good crop for 100 years or longer. One disadvantage of air-layering is that the resultant trees have weak root systems. In China, a crude method of cleft-grafting has long been employed for special purposes, but, generally speaking, the lychee has been considered very difficult to graft. Bark, tongue, cleft, and side-veneer grafting, also chip-and shield-budding, have been tried by various experimenters in Florida, Hawaii, South Africa and elsewhere with varing degrees of success. The lychee is peculiar in that the entire cambium is active only during the earliest phases of secondary growth. The use of very young rootstocks, only 1/4 in (6 mm) in diameter and wrapping the union with strips of vinyl plastic film, have given good results. A 70% success rate has been achieved in splice-grafting in South Africa. Hardened-off, not terminal, wood of young branches 1/4 in (6 mm) thick is first ringed and the bark-ring removed. After a delay of 21 days, the branch is cut off at the ring, defoliated but leaving the base of each petiole, then a slanting cut is made in the rootstock 1 ft (30 cm) above the soil, at the point where it matches the thickness of the graftwood (scion), and retaining as many leaves as possible. The cut is trimmed to a perfectly smooth surface 1 in (2.5 cm) long the scion is then trimmed to 4 in (10 cm) long, making a slanting cut to match that on the rootstock. The scion should have 2 slightly swollen buds. After joining the scion and the rootstock, the union is wrapped with plastic grafting tape and the scion is completely covered with grafting strips to prevent dehydration. In 6 weeks the buds begin to swell, and the plastic is slit just above the bud to permit sprouting. When the new growth has hardened off, all the grafting tape is removed. The grafting is performed in a moist, warm atmosphere. The grafted plants are maintained in containers for 2 years or more before planting out, and they develop strong taproots.
In India, a more recent development is propagation by stooling, which has been found "simpler, quicker and more economical" there than air-layering. First, air-layers from superior trees are planted 4 ft (1.2 m) apart in "stool beds" where enriched holes have been prepared and left open for 2 weeks. Fertilizer is applied when planting (at the beginning of September) and the air-layers are well established by mid-October and putting out new flushes of growth in November. Fertilizer is applied again in February-March and June-July. Shallow cultivation is performed to keep the plot weed-free. At the end of 2 1/2 years, in mid-February, the plants are cut back to 10 in (25 cm) from the ground. New shoots from the trunk are allowed to grow for 4 months. In mid-June, a ring of bark is removed from all shoots except one on each plant and lanolin paste containing IBA (2,500 ppm) is applied to the upper portion of the ringed area. Ten days later, earth is heaped up to cover 4 to 6 in (10-15 cm) of the stem above the ring. This causes the shoots to root profusely in 2 months. The rooted shoots are separated from the plant and are immediately planted in nursery beds or pots. Those which do not wilt in 3 weeks are judged suitable for setting out in the field. The earth around the parent plants is leveled and the process of fertilization, cultivation, ringing and earthing-up and harvesting of stools is repeated over and over for years until the parent plants have lost their vitality. It is reported that the transplanted shoots have a survival rate of 81-82% as compared with 40% to 50% in air-layers.
Spacing: For a permanent orchard, the trees are best spaced 40 ft (12 m) apart each way. In India, a 30 ft spacing is considered adequate, probably because the drier climate limits the overall growth. Portions of the tree shaded by other trees will not bear fruit. For maximum productivity, there must be full exposure to light on all sides.
In the Cook Islands, the trees are planted on a 40 x 20 ft (12 x 6 m) spacing56 trees per acre (134 per ha)but in the 15th year, the plantation is thinned to 40 x 40 ft (12 x l2 m).
Wind protection: Young trees benefit greatly by wind protection. This can be provided by placing stakes around each small tree and stretching cloth around them as a windscreen. In very windy locations, the entire plantation may be protected by trees planted as windbreaks but these should not be so close as to shade the lychees. The lychee tree is structurally highly wind-resistant, having withstood typhoons, but shelter may be needed to safeguard the crop. During dry, hot months, lychee trees of any age will benefit from overhead sprinkling they are seriously retarded by water stress.
Fertilization: Newly planted trees must be watered but not fertilized beyond the enrichment of the hole well in advance of planting. In China, lychee trees are fertilized only twice a year and only organic material is used, principally night soil, sometimes with the addition of soybean or peanut residue after oil extraction, or mud from canals and fish ponds. There is no great emphasis on fertilization in India. It has been established that a harvest of 1,000 lbs (454.5 kg) removes approximately 3 lbs (1,361 g) K 2 O, 1 lb (454 g) P 2 O 5 , 1 lb (454 g) N, 3/4 lb (340 g) CaO, and 1/2 lb (228 g) MgO from the soil. It is judged, therefore, that applications of potash, phosphate, lime and magnesium should be made to restore these elements.
Fertilizer experiments on fine sand in central Florida have shown that medium rates of N (either sulfate of ammonia or ammonium nitrate), P 2 O 5 , K 2 O, and MgO, together with one application of dolomite limestone at 2 tons/acre (4.8 tons/ha) are beneficial in counteracting chlorosis and promoting growth, flowering and fruit-set and reducing early fruit shedding. Excessive use of nitrogen suppresses growth and interferes with the uptake of other nutrients. If vegetative dormancy is to be encouraged in bearing trees, fertilizer should be withheld in fall and early winter.
In limestone soil, it may be necessary to spread chelated iron 2 or 3 times a year to avoid chlorosis. Zinc deficiency is evidenced by bronzing of the leaves. It is corrected by a foliar spray of 8 lbs (3.5 kg) zinc sulphate and 4 lbs (1.8 kg) hydrated lime in 48 qts (45 liters) of water. Because of the very shallow root system of the lychee, a surface mulch is very beneficial in hot weather.
Pruning: Ordinarily, the tree is not pruned after the judicious shaping of the young plant, because the clipping off of a branch tip with each cluster of fruits is sufficient to promote new growth for the next crop. Severe pruning of old trees may be done to increase fruit size and yield for at least a few years.
Girdling: The Indian farmer may girdle the branches or trunk of his lychee trees in September to enhance flowering and fruiting. Tests on 'Brewster' in Hawaii confirmed the much higher yield obtained from branches girdled in September. Girdling of trees that begin to flush in October and November is ineffective. Similar trials in Florida showed increased yield of trees that had poor crops the previous year, but there was no significant increase in trees that had been heavy bearers. Furthermore, many branches were weakened or killed by girdling. Repeated girdling as a regular practice would probably seriously interfere with overall growth and productivity.
Indian horticulturists warn that girdling in alternate years, or girdling just half of the tree, may be preferable to annual girdling and that, in any case, heavy fertilization and irrigation should precede girdling. Fall spraying of growth inhibitors has not been found to increase yields.
For home use or for local markets, lychees are harvested when fully colored for shipment, when only partly colored. The final swelling of the fruit causes the protuberances on the skin to be less crowded and to slightly flatten out, thus an experienced picker will recognize the stage of full maturity. The fruits are rarely picked singly except for immediate eating out-of-hand, because the stem does not normally detach without breaking the skin and that causes the fruit to spoil quickly. The clusters are usually clipped with a portion of stem and a few leaves attached to prolong freshness. Individual fruits are later clipped from the cluster leaving a stub of stem attached. Harvesting may need to be done every 3 to 4 days over a period of 3-4 weeks. It is never done right after rain, as the wet fruit is very perishable. The lychee tree is not very suitable for the use of ladders. High clusters are usually harvested by metal or bamboo pruning poles. A worker can harvest 55 lbs (25 kg) of fruits per hour.
The yield varies with the cultivar, age, weather, presence of pollinators, and cultural practices. In India, a 5-year-old tree may produce 500 fruits, a 20-year-old tree 4,000 to 5,000 fruits160 to 330 lbs (72.5-149.6 kg). Exceptional trees have borne 1,000 lbs (455 kg) of fruit per year. One tree in Florida has borne 1,200 lbs (544 kg). In China, there are reports of 1,500 lb crops (680 kg). In South Africa, trees 25 years old have averaged 600 lbs (272 kg) each in good years and an average yield per acre is approximately 10,000 lbs annually (roughly equivalent to 10,000 kg per hectare).
Freshly picked lychees keep their color and quality only 3 to 5 days at room temperature. If pre-treated with 0.5% copper sulphate solution and kept in perforated polyethylene bags, they will remain fresh somewhat longer.
Fresh fruits, picked individually by snapping the stems and later de-stemmed during grading, and packed in shallow, ventilated cartons with shredded-paper cushioning, have been successfully shipped by air from Florida to markets throughout the United States and also to Canada. In South Africa, freshly picked lychees have been placed on trays in ventilated sheds, dusted with sulphur and left overnight, and then allowed to "wilt" in lugs for 24 to 48 hours to permit any infested or injured fruits to become conspicuous before grading and packing. It is said that fruits so treated retain their fresh color and are unaffected by fungi or pests for several weeks.
In China and India, lychees are packed in baskets or crates lined with leaves or other cushioning. The clusters or loose fruits are best packed in trays with protective sheets between the layers and no more than 5 single layers or 3 double layers are joined together. The pack should not be too tight. Containers for stacked trays or fruits not so arranged, must be fairly shallow to avoid too much weight and crushing. Spoilage may be retarded by moistening the fruits with a salt solution.
In the Cook Islands, the fruits are removed from the clusters, dipped in Benlate to control fungal growth, dried on racks, then packed in cartons for shipment to New Zealand. South African shippers immerse the fruits for 10 minutes in a suspension of 0.375 dicloran 50% wp plus 0.625 g benomyl 50% wp per liter of water warmed to 125.6º F (52º C). Tests at CSIRO, Div. of Food Research, New South Wales, Australia, in 1982, showed good color retention, retardation of weight loss and fungal spoilage in lychees dipped in hot benomyl 0.05% at 125.6º F (52º C) for two minutes and packed in trays with PVC "skrink" film covering. The chemical treatment had not yet been approved by health authorities.
Lychee clusters shipped to France by air from Madagascar have arrived in fresh condition when packed 13 lbs (6 kg) to the carton and cushioned with leaves of the traveler's tree (Ravenala madagascariensis Sonn.).
Boat shipment requires hydrocooling at the plantation at 32º-35.6º F (0º-2º C), packing in sealed polyethylene bags, storing and conveying to the port at -4º to -13º F (-20º--25º C) and shipping at 32º to 35.6º F (0º-2º C).
In Florida, fresh lychees in sealed, heavy-gauge polyethylene bags keep their color for 7 days in storage or transit at 35º to 50º F (1.67º-10º C). Each bag should contain no more than 15 lbs (6.8 kg) of fruit.
Lychees placed in polyethylene bags with moss, leaves, paper shavings or cotton packing have retained fresh color and quality for 2 weeks in storage at 45º F (7.22º C) for a month at 40º F (4.44º C). At 32º to 35º F(0º-1.67º C) and 85% to 90% relative humidity, untreated lychees, can be stored for 10 weeks the skin will turn brown but the flesh will be virtually in fresh condition but sweeter.
Frozen, peeled or unpeeled, lychees in moisture-vapor-proof containers keep for 2 years.
|Plate XXXIII: LYCHEE, Litchi chinensis: dried|
Lychees dehydrate naturally. The skin loses its original color, becomes cinnamon-brown, and turns brittle. The flesh turns dark-brown to nearly black as it shrivels and becomes very much like a raisin. The skin of 'Kwai Mi' becomes very tough when dried that of 'Madras' less so. The fruits will dry perfectly if clusters are merely hung in a closed, air-conditioned room.
In China, lychees are preferably dried in the sun on hanging wire trays and brought inside at night and during showers. Some are dried by means of brick stoves during humid weather.
When exports of dried fruits from China to the United States were suspended, India welcomed the opportunity to supply the market. Experimental drying involved preliminary disinfection by immersing the fruits in 0.5% copper sulphate solution for 2 minutes. Sun-drying on coir-mesh trays took 15 days and the results were good except that thin-skinned fruits tended to crack. It was found that shade-drying for 2 days before full exposure to the sun prevented cracking.
Electric-oven drying of single layers arranged in tiers, at 122º to 140º F (50º-65º C), requires only 4 days. Hot-air-blast at 160º F(70º C) dries seedless fruits in 48 hours. Fire-oven and vacuum-oven drying were found unsatisfactory. Florida researchers have demonstrated the feasibility of drying untreated lychees at 120º F (48.8º C) with free-stream air flow rates above 35 CMF/f 2 . Drying at higher temperatures gave the fruits a bitter flavor.
The best quality and light color of flesh instead of dark-brown is achieved by first blanching in boiling water for 5 minutes, immersing in a solution of 2% potassium metabisulphite for 48 hours, and dipping in citric acid prior to drying.
Dried fruits can be stored in tins at room temperature for about a year with no change in texture or flavor.
In most areas where lychees are grown, the most serious foliage pest is the erinose, or leaf-curl, mite, Aceria litchii, which attacks the new growth causing hairy, blister-like galls on the upperside of the leaves, thickening, wrinkling and distorting them, and brown, felt-like wool on the underside. The mite apparently came to Florida on plants from Hawaii in 1953 but has been effectively eradicated. A leaf-webber, Dudua aprobola, attacks the new growth of all lychee trees in the Punjab.
The most destructive enemy of the lychee in China is a stinkbug (Tessaratoma papillosa) with bright-red markings. It sucks the sap from young twigs and they often die at least there is a high rate of fruit-shedding. This pest is combatted by shaking the trees in winter, collecting the bugs and dropping them into kerosene. Without such efforts, it works havoc. A stinkbug (Banasa lenticularis) has been found on lychee foliage in Florida. The leaf-eating false-unicorn caterpillar (Schizura ipomeae), which is parasitized by a tachinid fly (Thorocera floridensis) feeds on the leaves. The foliage is sometimes infested with red spider mites (Paratetranychus hawaiiensis). The citrus aphid (Toxoptera aurantii) preys on flush foliage. Two leaf rollers, Argyroploce leucaspis, and A. aprobola, are active on lychee trees in India. Thrips (Dolicothrips idicus) attack the foliage and Megalurothrips (Taeniothrips) distalis and Lymantria mathura damage the flowers.
A twig-pruner, Hypermallus villosus, has damaged lychee trees in Florida and a twig borer, Proteoteras implicata, has killed twigs of new growth on Florida lychees. The larvae of a native leaf beetle, Exema nodulosa, has been found puncturing and girdling lychee branchlets 1/8 to 1/4 in (3-6 mm) thick. Ambrosia beetles bore into the stems of young trees and fungi enter through their holes. A shoot-borer, Chlumetia transversa, is found on lychee trees all over India. Two bark-boring caterpillars, Indarbela quadrinotata and I. tetraonis, bore rings around the trunk underneath the bark of older trees. The larvae of a small moth, Acrocerops cramerella, eat developing seeds and the pith of young twigs. A small parasitic wasp helps to control this predator, as does the sanitary practice of burning the fallen lychee leaves.
The aphid (Aphis spiraecola) occurs on young plants in shaded nurseries, as does the armored scale, or lychee bark scale, Pseudaulacaspis major, and white peach scale, P. pentagona. The Florida red scale, Chrysomphalus aonidum, has been seen on lychee trees, also the banana-shaped scale, Coccus acutissimus, and green-shield scale, Pulvinaria psidii. The latter is the second most serious pest in Florida. Others are the six-spotted mite, Eotetranychus sexmaculatus, the leaf-footed bug, Leptoglossus phyllopus, and less troublesome creatures such as the several species of Scarabaeidae (related to June bugs) which attack leaves and flower buds.
In South Africa, the parasitic nematode Hemicriconemoides mangiferae and Xiphinema brevicolle cause die-back, decline and ultimately death of lychee trees, sometimes devastating orchards. The root-knot nematode, Meloidogyne javanica, also attacks the lychee in South Africa but is less prevalent.
In Florida, the southern green stinkbug, Nezara viridula, and the larvae of the cotton square borer, Strymon metinus, attack the fruit. Seed-feeding Lepidoptera, especially Cryptophlebia ombrodelta and Lobesia sp. cause much fruit damage and falling in northern Queensland. Carbaryl sprays considerably reduce the losses. In South Africa, a moth, Argyroploce peltastica, lays eggs on the surface of the fruit and the larvae may penetrate weak areas of the skin and infest the flesh. The fruit flies, Ceratites capitata and Pterandrus rosa make minute holes and cracks in the skin and cause internal decay. These pests are so detrimental that growers have adopted the practice of enclosing bunches of clusters (with most of the leaves removed) in bags made of "wet-strength" paper or unbleached calico 6 to 8 weeks before harvest-time. The Caribbean fruit fly, Anastrepha suspensa, has attacked lychee fruits in Florida.
Birds, bats and bees damage ripe fruits on the trees in China and sometimes a stilt house is built beside a choice lychee tree for a watchman to keep guard and ward off these predators, or a large net may be thrown over the tree. In Florida, birds, squirrels, raccoons and rats are prime enemies. Birds have been repelled by hanging on the branches thin metallic ribbons which move, gleam and rattle in the wind. Grasshoppers, crickets, and katydids may, at times, feed heavily on the foliage.
Few diseases have been reported from any lychee-growing locality. The glossy leaves are very resistant to fungi. In Florida, lychee trees are occasionally subject to green scurf, or algal leaf spot (Cephaleuros virescens), leaf blight ( Gleosporium sp.), die-back, caused by Phomopsis sp., and mushroom root rot (Clitocybe tabescens) which is most likely to attack lychee trees planted where oak trees formerly stood. Old oak roots and stumps have been found thoroughly infected with the fungus.
In India, leaf spot caused by Pestalotia pauciseta may be prevalent in December and can be controlled by lime-sulphur sprays. Leaf spots caused by Botryodiplodia theobromae and Colletotrichum gloeosporioides, which begin at the tip of the leaflet, were first noticed in India in 1962.
Lichens and algae commonly grow on the trunks and branches of lychee trees.
The main post-harvest problem is spoilage by the yeast-like organism, which is quick to attack warm, moist fruits. It is important to keep the fruits dry and cool, with good circulation of air. When conditions favor rotting, dusting with fungicide will be necessary.
|Fig. 73: Peeled, seeded, lychees (Litchi chinensis) are canned in sirup in the Orient and exported to the United States and other countries.|
Lychees are most relished fresh, out-of-hand. Peeled and pitted, they are commonly added to fruit cups and fruit salads. Lychees stuffed with cottage cheese are served as salad topped with dressing and pecans. Or the fruit may be stuffed with a blend of cream cheese and mayonnaise, or stuffed with pecan meats, and garnished with whipped cream. Sliced lychees, congealed in lime gelatin, are served on lettuce with whipped cream or mayonnaise. The fruits may be layered with pistachio ice cream and whipped cream in parfait glasses, as dessert. Halved lychees have been placed on top of ham during the last hour of baking, or grilled on top of steak. Pureed lychees are added to ice cream mix. Sherbet is made by extracting the juice from fresh, seeded lychees and adding it to a mixture of prepared plain gelatin, hot milk, light cream, sugar and a little lemon juice, and freezing.
Peeled, seeded lychees are canned in sugar sirup in India and China and have been exported from China for many years. Browning, or pink discoloration, of the flesh is prevented by the addition of 4% tartaric acid solution, or by using 30º Brix sirup containing 0.1% to 0.15% citric acid to achieve a pH of about 4.5, processing for a maximum of 10 minutes in boiling water, and chilling immediately.
*According to analyses made in China, India and the Philippines.
The lychee is low in phenols and non-astringent in all stages of maturity.
To a small extent, lychees are also spiced or pickled, or made into sauce, preserves or wine. Lychee jelly has been made from blanched, minced lychees and their accompanying juice, with 1% pectin, and combined phosphoric and citric acid added to enhance the flavor.
The flesh of dried lychees is eaten like raisins. Chinese people enjoy using the dried flesh in their tea as a sweetener in place of sugar.
Whole frozen lychees are thawed in tepid water. They must be consumed very soon, as they discolor and spoil quickly.
In China, great quantities of honey are harvested from hives near lychee trees. Honey from bee colonies in lychee groves in Florida is light amber, of the highest quality, with a rich, delicious flavor like that of the juice which leaks when the fruit is peeled, and the honey does not granulate.
Medicinal Uses: Ingested in moderate amounts, the lychee is said to relieve coughing and to have a beneficial effect on gastralgia, tumors and enlargements of the glands. One stomach-ulcer patient in Florida, has reported that, after eating several fresh lychees he was able to enjoy a large meal that, ordinarily, would have caused great discomfort. Chinese people believe that excessive consumption of raw lychees causes fever and nosebleed. According to legends, ancient devotees have consumed from 300 to 1,000 per day.
In China, the seeds are credited with an analgesic action and they are given in neuralgia and orchitis. A tea of the fruit peel is taken to overcome smallpox eruptions and diarrhea. In India, the seeds are powdered and, because of their astringency, administered in intestinal troubles, and they have the reputation there, as in China, of relieving neuralgic pains. Decoctions of the root, bark and flowers are gargled to alleviate ailments of the throat. Lychee roots have shown activity against one type of tumor in experimental animals in the United States Department of Agriculture/National Cancer Institute Cancer Chemotherapy Screening Program.