- B Snijder and P J C Stassen
- Institute for Tropical and Subtropical Crops, Private Bag X11208, Nelspruit 1200
- 1998
Research into pruning and manipulation of litchi trees has only started recently. The results obtained with pruning of four-year-old litchi trees during the 1996 season showed that pruning is advantageous for the producer as it develops a stronger and better framework for the tree. This reduces branch breakage during strong winds. The trial trees are, however, still too young for yield results to be available.
Pruning of older trees at Levubu showed that tree shape and size can be maintained with pruning. A problem discovered when mature trees are pruned was the tendency for the trees to go into a juvenile growth phase. Research is currently concentrating on the control of regrowth and shortening of this Juvenile phase.
Summary:
- Research into pruning and manipulating litchi trees is relatively recent, but initial results indicate that pruning can strengthen trees, improve framework, and minimize branch breakage during strong winds.
- Early trials involved both young and mature litchi trees, investigating various pruning methods and high-density plantings to optimize orchard space and economic potential.
- Trials at the Burgershall Research Station tested plant spacings from 166 to 2,000 trees per hectare, with treatments including regular pruning, girdling, and chemical growth control.
- Regrowth management after pruning is a key challenge, especially since mature trees tend to revert to a juvenile growth phase when pruned, leading to low yields for at least two seasons.
- Girdling was found to induce fruit set, but overly severe girdling harmed young trees, indicating a need for gentler practices such as cincturing instead of deep cutting.
- Pruned trees generally had less foliage density and reduced breakage but struggled with fruiting depending on regrowth and autumn flush control.
- In high-density orchards, precise and timely pruning and thinning are necessary to prevent overcrowding and maintain regular yields; mechanical hedging and selective pruning were evaluated for their effectiveness.
- Training airlayered saplings with a central leader system and employing tipping at correct stages improved tree structure and branching angles.
- Severe pruning in mature orchards resulted in significant yield loss and slow recovery; thinning alternate rows increased cumulative yield compared to untouched controls.
- Chemical treatments are being tested to enhance fruitfulness, flowering, fruit retention, and curb excessive growth, with promising early indications.
- Overall, while yield data from these manipulations is still limited, pruning and training methods show potential for improving litchi production in high-density systems, but more research is needed on regrowth control and long-term effects.