- R L Morse1 and J H Oosthuizen2
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1Principal Extension Officer, Agricultural Extention Office, P O Box 266, Nelspruit 1200
2Institute for Tropical and Subtropical Crops, Private Bag X11208, Nelspruit 1200 - 1993
The litchi is one of the least adaptable crops to some tropical and sub-tropical conditions. Since they require a period of vegetative dormancy in the terminal shoots to initiate flowering, litchi trees will only flower well in areas with a cool, dry autumn-winter period every year. Litchi trees tend to flush more than once after harvest, during periods of warm and sometimes wet weather in winter months. This phenomenon reduces the formation of panicles and flowers. The lack of winter stress can be overcome by using the girdling technique. A 3 mm wide strip of bark must be removed around the main frame branches, down to the xylem (wood). By removing the piece of bark, translocation of sugars and growth inhibitors between the leaves and roots is prohibited and causes a build-up in the leaves, which promotes flower development. If litchi growers want to experiment with girdling, the following should be kept in mind:
- It is very important that only very healthy, vigorous trees with a strong post-harvest flush are girdled.
- Repeated annual girdling is now being investigated and cannot be recommended unless trees are very vigorous.
- Proper fertilisation and irrigation are necessary when trees are girdled, especially after they have produced a heavy crop.