Future Orchards Trial Report 2014
Project title:
Region:
Contact person:
Project
Objective:
Root pruning of Pink Lady trees
Orange,NSW
FLA: Stephen Tancred. Trial orchardist: Michael Cunial
Pink Lady is a naturally vigorous variety and when grown on anything but
dwarfing rootstocks usually needs some form or summer vigour control to
maximise fruit quality (eg summer pruning, Regalis, root-pruning). If grown
in deep fertile soil (like in Orange) the problem can be made worse.
This trial aimed to;
1. Look at the practicalities of root pruning Pink Lady trees
2. Compared single and double sided root pruning
Method:
The trial was not a formally set up trial as part of the Future orchards
program, but was taken into the FO program when it was shown to us by
the grower at the farm visits associated with the November 2013 Orchard
Walk.
Trees received root pruning in late winter. The grower pruned some rows
on 1 side and some on 2 sides and thankfully left some rows untreated as
Controls.
It was observed that shoot growth in November was more vigorous on trees
that did not receive root pruning. Photos of the sunlight/shade falling
under trees demonstrated this.
Attempts to measure the number and length of shoots were made at the
end of November, but as the FLA was not resident the tree selection and
methods were not robust. Data collected is not presented as it may be
misleading and doesn’t match the visual record.
Fruit sizing measurements were collected off the trees that were ripped
once, twice and not at all. The data initially showed the root pruned fruit to
be growing faster, but not so later in the season. Because only 20 fruit per
treatment were measured it may not be valid to present this to growers as
a genuine trend.
What did we learn?
The results are qualitative.
1. Photos taken in November demonstrate the additional light that was penetrating the
canopy of the root pruned trees.
2. Photos in April show the extra foliage that summer pruned off the trees that won’t root
pruned.
3. Fruit colour differences are also visible in the April photos.
No Root Pruning - 7th Nov. 13
Root Pruning 2 Sides - 7th Nov. 13
No Root Pruning - 15th April 14
Root Pruning 2 Sides - 15th April 14
No Root Pruning - 15th April 14
Root Pruning 2 Sides - 15th April 14
Implications.
Root pruning may have some positive benefits for increased light penetration into over-vigorous
apple canopies, a reduction in summer pruning and improvement in fruit colour at harvest. Root
pruning may be a lower cost alternative to the use of the PGR Regalis, and may have cost savings
compared to summer pruning. Fruit colour was improved when observed 3-4 weeks before
harvest but was not observed at harvest as summer pruning had been conducted and all
treatments received Extenday treatment to improve fruit colour.
How will this impact on the business?
The practice has been accepted by the business as a useful tool and will be further explored on
other blocks and varieties.
What will we change?
If the practice is to be further adopted and recommended then some more robust metrics ned to
be collected eg shoot lengths, time to summer prune, improvements in % fruit colour etc.
What are the road blocks/obstacles to change?
The availability of equipment in the Orange district is a short term obstacle. Growers will make or
buy or borrow equipment to overcome this.
The orchard only had overhead irrigation and the removal of a large proportion of the feeder roots
was a risk if a dry season eventuated! There was a long period in late summer when the weather
was dry and trees may have suffered unduly. The grower has recognised this and plans to convert
the block to trickle irrigation next season.
Summary.
Root pruning is a useful vigour control in many districts. It was tried as a grower
demonstration in orange on over-vigorous Pink Lady trees. Annual shoot growth was reduced and
light interception by the tree canopy improved. Less summer pruning was needed and fruit colour
on root-pruned trees was improved a month from harvest.