Pg. 58 Tree Manipulation and Pruning of Young and Bearing Litchi Trees in High-Density Orchards

The litchi has a worldwide reputation of being a poor yielding crop and its yield may be worsened by alternate bearing. Litchi producers in South Africa are also experiencing low annual yields that are partly due to the wide tree spacings of 10 x 10 m. With annual yields ranging between 4 and 8 ton/ha and some productive growers getting more that 10 ton/ha, the situation still looks bad compared with countries like Israel where the production reaches 15 ton/ha. The ideal solution to the low yield problem would probably be to increase planting density.

Summary:

• Litchi is known globally as a poor yielding crop, with yields worsened by alternate bearing.
• South African litchi producers experience low annual yields partly due to wide tree spacing (10 x 10 m).
• Yields range between 4 and 8 tons per hectare in South Africa, compared to 15 tons per hectare in countries like Israel.
• Increasing planting density is seen as a potential solution to low yields.
• Research on pruning and manipulation of litchi trees in high-density plantings is limited.
• The study aimed to find suitable, economically viable management strategies for high-density litchi production using different manipulation and pruning techniques.
• High-density planting also promotes earlier yield returns, important given the 4-6 year time before trees typically produce.
• Trials were conducted at Levubu Experimental Station with tree spacings initially at 6 x 6 m and thinned to 8.5 x 12 m or 12 x 6 m.
• Treatments included girdling, pruning to different tree structures, and paclobutrazol applications.
• Trees pruned annually after harvest showed significantly higher yields than unpruned controls.
• Girdling also increased yields, especially when combined with pruning.
  Paclobutrazol use has been discontinued.
• Despite improvements, yields are still low compared to other subtropical crops.
• High-density planting at Burgershall Research Station is ongoing, with trees trained under different systems but not yet bearing fruit, so no conclusions can be drawn yet.
• The results suggest managing tree size through pruning after harvest and using girdling in off-years to improve flowering and yields.
• This summary captures the key points on tree manipulation and pruning in high-density litchi orchards as studied in South Africa to improve yield challenges.