A demonstration on girdling on litchi trees was held at the Flacq Model Farm on the 21st May 2025. Fifteen litchi growers were present for the demonstration. The objectives of the training were to showcase effective methods to initiate flowering, with emphasis on girdling and tipping techniques. The training also aimed to enhance growers’ understanding of the phenological development of litchi and provide hands-on guidance for managing flowering through timely interventions.
As the flowering period for litchi approaches, it becomes essential to correctly identify and manage its phenological stages to optimise yield. During April/May, the litchi plant undergoes a period of water stress leading the terminal shoots into dormancy stage with a flattened bud. However, under unfavourable conditions, such as rainfall and high temperature, the plant will break dormancy prematurely. As a result, the terminal buds develop into new leaves rather than flower panicles, ultimately hindering the flowering process (see photos below). In order to initiate flowering, different techniques such as girdling, tipping and ethrel (ethephon) application can be adopted.
Girdling Technique
Girdling is the removal and cutting through the bark around the circumference of the main trunk or branches of a tree. It is usually practised on selected branches of vigorously growing mature litchi trees at the fall of winter.
The cut must be deep enough, to a depth of 3 mm, to interrupt the downward movement of photosynthates from the leaves to the roots. Deeper cuts should be avoided to prevent damage of the vascular system and the risk of eventual death to girdled branches. Girdling knives are specifically designed to carry out this operation.
Girdling on litchi branches must be a spiral band to avoid risk of damaging the vascular system with circular girdle. Whenever terminal shoots of a mature litchi tree show signs of setting new vegetative flush in May/early June, 50% of its branches with diameters 4 to 5 cm can be girdled using a ‘girdling knife’ or any well-sharpened knife. The bark of the branch is removed around its circumference to a depth of about 3 mm in a spiral band. Girdled branches usually get through a resting phase of one to two months during which they will not set any new vegetative flush and are thus more apt to flower as temperature further decreases in winter.
Tipping
In case of litchi trees with short frames and lower canopies, manual tipping is done to eliminate vegetative flush emerging on terminal shoots, followed by girdling of the branches.
However, tipping is labour-intensive, not economical for large-scale plantations and inappropriate for tall trees. branches.
Use bioregulator ‘Ethephon’
Ethephon 48% is sprayed only on new vegetative flushes as soon as they appear on the panicles as red small leaves.
Spot application is done using a knapsack sprayer on accessible new vegetative flushes whereas a motorised blower is advisable for taller litchi trees.
The recommended dosage rate of Ethephon 48% in the spray solution is around 120 ppm or 0.25 mL per litre of water. Progressive withering till death of treated shoots (new vegetative flushes) is observed one week after application of Ethephon. Precautionary measures include the following:
Apply on new vegetative flush only
Spray when night temperatures go below 20°C
Use recommended dosage to avoid phytotoxicity