The quality of nursery trees is one of the most important factors when establishing an orchard. The profitabilty of any intensive pear orchard is related to its ability to produce early yields of quality fruit. This is highly dependant on trees having good growth and developing an adequate canopy structure in the early years after planting.

An adequate canopy structure is one that allows for optimal light interception and has enough buds with the capacity to produce flowers.  This is best achieved through using high quality nursery trees that already have in place a good canopy structure.

It is also important that nursery trees are healthy - that is free of pest and disease and mechanical injury.

Types of nursery trees

Which tree will give the best result for an intensive system? 

Ordering a nursery tree 

Further information

References

Types of nursery trees

There are a number of different types of nursery tree that can be used when planting an orchards. These include

1. One year old whips - produced through bench grafting of rootstocks in winter, planting in spring and then encouragement of a single bud to grow. These are often unbranched and can lack uniformity.
2. Summer budded trees - produced over two seasons with rootstocks planted in spring and budded in summer. These are headed at the bud in late winter, with the bud growing into a tree the next season.
3. Two year old feathered trees (or 'Knip' trees) - produced over 2 seasons. One year old trees produced through either bench grafting or summer budding are held over in the nursery for another year and in the second winter are headed to the required height (50-75cm). A single shoot is allowed to grow from the top bud and any laterals are removed. The shoot grows very vigorously and produces branches on the current seasons growth (called feathers).
4. Sleeping eye trees - summer budded rootstocks that are cut above the dormant bud and stored for planting in a nursery or orchard.

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Which trees will give the best results for an intensive system?

Many studies from around the world have shown that the use of  highly feathered nursery trees, such as the two year old well feathered (knip) trees  can result in significant yields in the second and third year after planting. This is compared to unbranched trees (or whips) that may take four or five years to produce a yield.   

Highly feathered trees such as the 'knip' trees are the most favoured nursery tree type in many European production systems.  

Generally the best quality 'knip' tree should have   

• A minimum tree height of 1.6m above graft union 
• A minimum stem diameter of 14-16mm measured at least 10cm above graft union
• A number (6-15) of well positioned feathers/laterals with a maximum length of 30cm
• Feathers starting no less than 80cm above the soil.
• Feathers with moderate vigour - that is wtih a  diameter no greater than 30% of the trunk.
• Feathers with wide crotch angles

Figure 1 & 2 : 'Knip' trees in Belgium.

Often these trees require little (or no) pruning at planting, particularly if feathers are already well located around the tree.  

The drawbacks of these trees is that they are produced at a higher cost and therefore will be more expensive than a one year whip.  However the production losses through using cheaper, poor quality trees will cost more money in the long term than the initial cost of using quality trees.  

It is important however that growers understand the requirement of their intended system before deciding on a nursery tree. Often as densities get higher (>4000 trees/ha) and spacings narrower, highly feathered trees become less desirable. Systems such as the super spindle (4000-7000 trees/ha) are often best planted with whips with short branches. These treese should still be of a good quality however (uniform in size and healthy). 

Sleeping eye trees can often be an option to keep tree cost down in very high density orchards. The danger with sleeping eye trees is that the risk of tree loss at planting can be higher. This was demonstrated by Elkins et al. (2008) who found that even though sleeping eye trees were cheaper than 'standard' nursery trees (similar to whips) the cost of replacement and intensive training negated the benefit of the lower purchase price.

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Ordering a nursery tree 

When ordering a nursery tree, growers need to consider what tree will give them the best start for their system. This requires a good understanding of the planting site and intended system. If growers want highly feathered nursery trees, they will need to order atleast 2-3 years in advance from the nursery. If whips are the tree of choice, there is less lead time required, but growers should still order with enough time to ensure best chance of starting a system with the highest quality trees.

Fundamentally,growers must develop a good relationship with their nursery in order to get the right tree for their system. Being able to clearly specify the requirements of a tree can make this a smooth transparent process. APFIP has released a guide to nursery tree specifications, a useful reference when ordering trees from a nursery. 

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Further information

These Australian sites may be useful for growers. However they are intended as an information source only. Any specific chemical or other management recommendations may be outdated or irrelevant for Australian conditions and growers should seek local advice.

Please note: By electing to visit sites linking from this page you will be leaving the intensivepear.com website.

Australian Resources

Nursery Tree Specification

• APFIP Nursery Tree Specifications - For information on nursery tree specifications (external link).

Planting nursery trees

• Go to the planting nursery tree page for more information on management of nursery trees at planting

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References

Elkins, R.B., DeJong, T.M., Klonksky, K., and DeMoura R. (2008). "Economic evaluation of high density versus standard orchard configurations; Case study using performance data for 'Golden Russet Bosc' pears". Acta Horticulturae 800: 739-746