Australian Lychee Growers Association represent the biosecurity interests of lychee growers and the industry.
In 2016–17, lychee production was valued at $26.7 million (LVP), with exports worth $5.6 million. Annual production continues to range between 2,250 to 3,500 tonnes, depending on climatic and seasonal conditions.
There are many varieties of lychee grown in Queensland and NSW, although the Kwai Mai Pink lychee is the most popular and widely grown variety and is a good annual yielding variety for export and domestic markets. A number of larger producers are now choosing to incorporate and plant some of the newer Chinese varieties of Chompogo, Erdon Lee and Baitangying in their orchards.
Lychees are produced as a single annual crop with a harvest period from late October (north Queensland) to March (northern NSW). This gives the Australian lychee season one of the world’s longest production periods as well as a counter-seasonal supply to most other lychee producing countries.
Lychee exports have experienced strong growth compared with other tropical fruits, with some 18 per cent of production being exported in 2017–18. Hong Kong is officially the largest market for Australian lychees, accounting for a little over half of Australia’s exports for 2017–18. Exports to the United Arab Emirates are less than half of that to Hong Kong but this market is showing very strong growth, followed by New Zealand, Singapore, Canada and the United States.
The lychee (Litchi chinensis) is a subtropical tree from the Sapindaceae family and is thought to be native to southern China. The lychee is an evergreen tree which grows to heights of more than 20 m. The lychee fruit is a drupe, 3–4 cm long and 3 cm in diameter, covered by a pink/red roughly textured rind which covers an inside layer of sweet and sour, translucent white flesh which surrounds the inner seed.
Although variable between growing regions, flowering usually occurs over a 6 week period from between July to October. Flowers are borne on multi-branched terminal inflorescences, which are generally referred to as flower panicles. A panicle can have up to 3,000 flowers, although only about 200 are pollinated and of these only 5 to 60 will develop into mature fruit.
There are three distinct flower types, two male types and one female, which are all borne on the same panicle. The usual sequence of flower opening, which occurs over a 2 to 6 week period, is male flower, female hermaphrodite flowers which set fruit, and male hermaphrodite flowers that do not set fruit. The male flowers in the first and third stages release pollen to fertilise the female flowers. Thus, there needs to be an overlap of the male stages with the female stage. Most of the pollen used for fertilisation is usually supplied by the third stage male hermaphrodite flowers.
Self-pollination may occur in lychee through wind pollination however, flowers are generally recognised as self-sterile and insects are beneficial because they can transport pollen from anther to stigma for fruit to set. Only partial overlapping between male and female flowering occurs within a cultivar and so inter-planting of at least two different cultivars is necessary for adequate fruit set. Several insects have been reported to visit lychee flowers overseas including Coleoptera, Hemiptera, Homoptera and Lepidoptera. However, the honey bee is widely recognised as the principal pollinator. In Australia, both honey bees and Tetragonula sp are found on lychee blossoms, but preliminary studies suggest that the native social bee (Tetragonula sp) may be too small to be effective pollinators of the fruit.
Many studies have shown significant increases in yield of lychee crops as a result of honey bee pollination, including fruit set being three times greater when inflorescences were open to honey bees when compared to trees that were bagged to exclude them.
Lychee yields can sometimes be unreliable, erratic and rarely approach the capacity of the tree. Crossed fruit are generally heavier and yields in rows with two cultivars adjacent to each other have been shown to be 36 per cent higher in lychee. All of these studies clearly show that lychee require at least one other cultivar and an abundance of insect pollinators for pollen transfer to assist with pollination by wind. Bringing in honey bee hives could be necessary to increase pollinator numbers, increase crossing between cultivars and produce a good quality yield. For this reason, it is recommended that 2-3 hives per ha would be adequate for optimal pollination of lychee.
Additional fact sheets and web links about the pollination of this crop are listed below. Please be aware that some of the information was developed overseas, and environmental and seasonal variations may occur.
Lychee and longan pollination fact sheet, The Pollination Program (Agrifutures Australia and Hort Innovation)
Lychee, Purdue University, Indiana
|Annual value of lychee production, 2009–17|
|Distribution of lychee production by state and territory 2016–17 (based on LVP)|
The pollination information is an excerpt from the Lychee and longan pollination fact sheet, The Pollination Program (Agrifutures Australia and Hort Innovation) and from personal communication with James Drinnan (Queensland DAF) and the Australian Lychee Growers’ Association.
The industry overview and graphs on the value of production and crop distribution are from the National Plant Biosecurity Status Report (2018), Plant Health Australia, Canberra