Rootstocks for intensive pear production

By Rod Jones, Ian Goodwin and Susanna Turpin

DEPI scientists share their progress on trying to identify which pear rootstock / variety combinations perform best in intensive pear production systems.

By definition, intensive pear production systems use more than 1,000 trees per hectare and can achieve more than 8,000 trees per hectare depending on rootstock/scion combination and pruning and training system used (Table 1). The aim of intensive pear production systems is to get early returns on capital and consistently high yields of good quality fruit with lower labour costs.

Density Number of trees per hectare
Low Less than 1,000
Moderate 1,000 to 2,500
High 2,500 to 4,000
Very High 4,000 – 8,000
Ultra High Over 8,000
Table 1. Definitions of pear planting densities, where intensive production systems use greater than 1,000 trees per ha.

Intensive pear orchards can potentially offer improved production efficiency through:

  • Earlier bearing and therefore quicker returns on investment.
  • Improved and more consistent fruit quality.
  • Increased labour efficiencies after establishment (e.g. ease of harvesting, pruning and training).
The new red-blushed variety ‘ANP-0118’ is being tested with different rootstocks to determine which rootstocks are most appropriate for intensive production.

The new red-blushed variety ‘ANP-0118’ is being tested with different rootstocks to determine which rootstocks are most appropriate for intensive production.

When deciding to invest in an intensive system, growers need to make important decisions regarding variety and rootstock, training system and planting density. These must be tailored to suit local conditions. Studies in apple have shown that training systems, rootstocks and planting density have increased precocity and productivity, but little research has been done on pears. This is being addressed with work in the DEPI Tatura Pear Field Laboratory.

The most important decisions in establishing intensive pear orchards are:

  • Variety and rootstock – Research has shown that the choice of rootstock can have a significant effect on gross returns in pear orchards (Elkins et al. 2008).
  • Training system – Light interception should be maximised while avoiding excessive internal shading or over-exposure of fruit. Higher early yields have been reported on multi-leader systems compared to single leader trees in some experiments in Europe (Musacchi 2008). However, these higher yields have sometimes been at the expense of fruit size.
  • Pruning techniques – Tree pruning (including branch angle manipulation) can impact vigour, precocity, flowering intensity, fruit set and branching habits of pears (Sansavini and Musacchi 1994, du Plooy et al. 2002).
  • Tree density – In Australia, the HAL-funded project ‘A New Approach to Growing Williams’ Pears Profitably’ (FR02053) demonstrated that moderate tree density on the Open Tatura trellis training system is financially attractive for fresh market ‘Williams’ pears in Australia, but management of young trees is critical for early and high yields.

New rootstocks for intensive production

Rootstocks with reduced vigour compared to D6 rootstock are needed in intensive production. The Australian Pome Fruit Improvement Program (APFIP) established the National Pear Rootstock Trial ‘AP10016’ in the Goulburn Valley in 2004 to compare the performance of ‘Packham’, ‘Williams’ and ‘Corella’ pears on four rootstocks: D6, BP1, BM2000 and Quince A.

Pyro Dwarf and DCA Fox11 were also selected for planting, but only a small number of DCA Fox 11 were planted in 2009. These rootstocks were selected as they are around 60% the size of D6.

Two tree training systems (Open Tatura and Central Leader) have been used. Performance of the rootstocks varied with both the scion variety and tree training system, but after nine years it is clear that Quince rootstocks perform well with ‘Packham’ and ‘Corella’. These are now the preferred rootstock for high-density pear plantings in the Goulburn Valley.

Performance of some rootstock and scion combinations:

Quince A

‘Packham’ on Central Leader provided the highest production of fruit per cm² of trunk cross section area in season 2012. Highest production of ‘Corella’ was obtained on Quince A for both Central Leader and Open Tatura trellis over several seasons.

BP1

Showed reduced vigour and improved yield efficiency compared with D6 for both ‘Williams’ and ‘Packham’, particularly on Open Tatura trellis. BP1 is commercially available in Australia but numbers can be limited.

BM2000

Demonstrated medium vigour compared to D6 for both ‘Williams’ and ‘Packham’. Has the highest production of fruit per cm² of trunk cross section for ‘Williams’ on both Central Leader and Open Tatura trellis over several seasons.

In the Pear Field Laboratory at DEPI Tatura, the performance of three new red blushed pears ‘ANP-0131’, ‘ANP-0118’ and ‘ANP-0534’ is being evaluated on different rootstocks: D6, D6 with a Nijisseiki interstem, BP1, D6 with BM2000 interstem, Quince A and Quince C with Beurre Hardy interstems. All trees are trained to a four leader, Open Tatura trellis system. The primary aim is to determine which rootstocks are most appropriate for intensive production of each cultivar based on tree growth, precocity and yield.

New training systems for intensive production

Pears on a two-leader system on an Open Tatura trellis (4,444 trees per ha) - choosing an appropriate training system is critical for successful intensive pear production.

Pears on a two-leader system on an Open Tatura trellis (4,444 trees per ha) – choosing an appropriate training system is critical for successful intensive pear production.

Choosing an appropriate training system is critical for successful intensive pear production. In the Planting System experiment in the Pear Field Laboratory, the red-blushed cultivar ‘ANP-0131’ has been trained as multi-leader trees (2, 4, 6 or 8 leaders) on Open Tatura trellis, single or multi-leader trees (2, 4 or 6 leaders) in vertical hedgerow, freestanding Central Leader systems (at 0.5, 1.0 and 2.0 m tree spacing) or as a vase (the control treatment). Densities range from 741 to 4,444 trees per ha. As the trial was only recently set up in 2013, results are not yet available.

Trellis systems can reduce pruning and harvest costs as the tree structure is simple, particularly if the whole tree can be reached from the ground. However, establishment costs are often much higher than freestanding systems due to both the trellis construction and the early training of the trees.

References

Elkins, R., Klonsky, K., DeMoura, R. (2006) Comparison of Costs and Returns to Establish and Produce Specialty Pears on High Density Plantings with Sleeping Eye Trees and Standard Trees with Standard Planting – Lake and Mendocino Counties Musacchi 2008

Sansavini, S. and Musacchi, S. 1994. Canopy architecture, training and pruning in the modern european pear orchards: an overview. Acta Hort. 367:152-153.,

du Plooy, G., Jacobs, G., Cook, N.C. (2002). Quantification of bearing habit on the basis of lateral bud growth of seven pear cultivars grown under conditions of inadequate winter chilling in South Africa. Sci. Hort. 95:185-192.

About the authors

The authors are all from Victoria’s Department of Environment and Primary Industries: Rod Jones is a Senior Plant Pathologist, Ian Goodwin is the Research Manager – Horticulture Production Science, and Susanna Turpin is a Horticultural Scientist. For more information contact Ian (ian.goodwin@depi.vic.gov.au, 03 5833 5240) or Susanna (sue.richards@depi.vic.gov.au, 03 5833 5235).

Acknowledgements

This project was conducted as part of the apple and pear industry Productivity Irrigation Pests and Soils (PIPS) flagship programme, and funded by HAL using the apple and pear levy.

 

By |October 30th, 2014|PIPS, Varieties and rootstock|

About the Author:

Senior Plant Pathologist, Department of Economic Development, Jobs, Transport and Resources, Victoria