The bloom for the 2015 lychee season is beginning to emerge, thanks in part to the cool weather in November of 2014 leading up to Thanksgiving. Barring a hard winter freeze the late Spring early Summer lychee crop should be a very good one. The picture below shows an emerging bloom panicle of a Mauritius variety lychee tree. In three or four more weeks the flowers will become fully developed and the sex of the flower is easily determined.
Emerging 2015 lychee bloom panicle.
Of particular interest on the above photograph is the extensive damage to the leaves. We are often asked the question “What is easting my lychee tree”? This damage is from the Sri Lankan weevil (Myllocerus undatus) a member of the Coleoptera class (beetles) within the Insect phylum. The adult weevil feeds on a wide range of host plants . In Florida host records include at least 68 tropical fruit trees, palms, ornamental plants, upland cotton and citrus. The larvae of the weevil feed on roots, but the level of damage is hard to determine. The Apopka weevil, an early pest of lychee, cause extensive root damage.
We have observed these bugs on many types of fruit trees, but it would seem that they prefer the new growth of lychees more than mango or avocado.
(Myllocerus undecimpustulatus undatus)
This weevil was first introduced into Florida in 2000 and in 2006 had already spread to at least 12 counties. They feed around the margins of leaves and along the spine.
A weevil feeding
Unfortunately there is no effective way to control these bugs; however, lychee trees rapidly recover from the damage as they re-foliate and they tend to congregate on a single tree. You can manually remove adult weevils by shaking a branch over a pail of soapy water, but this is like pouring water into the ocean to make the tide rise. The bugs will simply repopulate from another source.
The insecticide Sevin (carbaryl) will kill all of the weevils on a tree, but we strongly recommend against using any insecticides on or around lychee trees as this will kill beneficial soil organisms if it gets into the soil food web.
Slightly later in the season when the bloom matures it will look like the photo shown below.
Lychee bloom panicle fully emerged
We are often asked if more than one lychee tree is required to get fruit, which is true for trees that are monecious. Monecious plants have separate male and female flowers on the same plant whereas plants that are dioecious have the male and female reproductive structures on separate plants. Lychee trees, which are members of the family Sapindaceae are monecious, whereas the genip or Spanish lime (Melicoccus bijugatus) and the rambutan (Nephelium lappaceum), also in the same family as the lychee, are dioecious and both male and female trees are required for fruit set or the tissue from male trees must be grafted onto the female (or vice versa).
As you will observe from the above photo the first flowers to emerge are the male flowers identifiable by their prominent stamen, the pollen bearing portion of the flower.
The female flowers emerge shortly thereafter and are identifiable by their prominent ovary.
Bee taking nectar from a lychee flower
In the above photo a bee is taking nectar from the calyx gland. To the right of the bee are female hermaphrodite flowers (with male and female sex parts) which shed viable pollen, but will not develop into a fruit. As can be observed from the above photo bees play a critical role in pollination, although other less desirable pollinators such as beetles can also transfer pollen from the shedding stamen to the receptive surface of the stigma. Wind can also play a role, but bees are the most important pollinator.
Male and female flowers of a No Mai Tze lychee
In the above photo you can observe clearly identifiable male and female flowers. Once pollen gets to the stigmatic surface the ovary will swell as the fruit develops. Unltimately, this is what you will eat.
Developing lychee fruit
In about 90 days after successful pollination you should expect to be seeing lychee fruit.
During the meantime you will observe the following on your tree>
Immature Mauritius lychee fruit
Another question that often comes up is whether it is useful to have more than one variety. My peronsal opinion is that you cannot have too many lychee trees, especially different varieties which ripen at different times during the season from mid May to mid July.
Ripe Brewster lychees ready to harvest
There is a practical reason for this. The Mauritius variety is typically the first to bloom during a season. Later on during the season the Brewster variety blooms. As the Brewster male flowers are emerging and maturing the female flowers of the Mauritius have receptive stigmatic surfaces and will benefit from the ripe male pollen from the Brewster trees. This leads to heavier fruit set. The Mauritius lychee can have extraordinary fruit sets when grown in the presence of Brewsters as evidenced by the photo shown below.
Mauritius fruit clusters
A 15 – 20 foot tall mature Mauritius tree can can upwards of 300 lbs or more of fruit in a good year.
Harvest time is both fun and hard work as the fruit must be picked in clusters with a pruning shears. The fruit is picked by cutting the panicle from the branch 6 – 12 inches below the section which holds the fruit. This is very important because this is a substitute for post harvest pruing. Trees that produce fruit every year and are pruned during the harvest season have a higher probability of fruiting again the following year if cool weather occurs during the winter season.
Harvested Sweet Heart lychee fruit
What does this all mean? Lychee fruit is perhaps the best tasting tropical fruit on the planet. Ask anyone from Asia what they think. Not only that the trees are superb ornamental evergreen hardwoods and they make a fantastic specimen tree in any landscape design.
Brewster lychee in a landscape setting
Watch this video for the update.