Future Orchards Trial: Final Report
Project title:
Region:
Contact:
Projective
Objectives:
Root Pruning – South Australia
Mount Lofty Ranges – South Australia
Paul James
1. Enhance local knowledge on root pruning and its impact on
vegetative growth
2. Provide a demonstration site to show the impacts
3. Obtain measurements and information for dissemination to growers
Outline/method/
(what you did ):
The demonstration site is 3 year old Fierro Fuji’s grafted onto 10 year old
M.26 rootstocks (previously Sundowner) still filling their allocated canopy
area. The trees are drip irrigated.
A root pruning demonstration site was set up in the most vigorous part of the
block. The site had the following treatments
1. Control – no ripping
2. Ripped both sides
3. Single Ripped – North side
4. Single ripped – South side
The ripping lines were a vertical incision 500mm from the trunk and 400mm
deep.
A visual inspection was held during summer 2013-4 and end of season
measurements will be taken to assess any differences between the different
Treatments.
Before and After
Control trees at trial commencement
Control trees – end of growing season
Results Summary** (averages of 20 measured trees)
Measurement
Control
Starting Circumference (cm)
End of season Circumference (cm)
% difference - tree circumference
Tree Height (m)
Number of Branches above 2.5 m*
15.8
17.5
10.8
4.59
26.2
Ripped
North Side
16.3
17.8
9.2
4.36
32.9
Double Rip
16.2
17.9
10.5
4.49
33.5
Ripped
South Side
15.9
17.6
10.7
4.53
33.3
*Branches below 2.5m had already been pruned at time of measurement
**After assessing these initial results no further measurements were undertaken.
No measurements of fruit yields of characteristics were recorded due to the comparatively low crop
yield (24.23 t/ha) and the trees being in their first significant crop year whilst still developing tree
canopy.
During the growing season due to the growth of the trees and bird damage the planned netting was
added to the block. The height of the net is 4.5 m above ground level.
Discussion
As seen in the results above, apart from a slight reduction in tree height for the North side ripped
treatment and a significant (approx. 27%) difference in actual branch numbers (>5cm and above 2.5
m) for the ripped trees there is no appreciable difference in tree performance.
It is concluded that whilst the treatments may have had some small (non-measured) impacts the 3
ripping treatments did not significantly influence tree canopy development in this season.
At a height of 4.5m for the netting – all of the trees have attained the desired tree height in their 3rd
season.
As the trees are drip irrigated it is hypothesised that the actual ripping treatments were not close
enough to the tree roots to have a significant impact on vegetative growth. Digging of the soil to test
this hypothesis has not been undertaken.
Implications
One of the questions asked about the block prior to commencement of the trial demonstration was
whether the trees would need their roots ripped in this their 3rd or the 4th growing season. The trial
demonstration was actually placed in the most vigorous growing section of the block to test this
question. Based on the tree growth and tree height attained it can be concluded that it was certainly
needed in this section of the block but was not effective enough. Consequently root ripping
strategies for next season (4th season) will be reassessed.
The proposed winter pruning target for this block is for 45 t/ha in 2015 based on 2.5 buds / fruit and
196 winter buds. Whilst the actual bud count cannot be provided due to pruning having commenced
at the time of actual measurements it is estimated that there were enough winter buds to achieve
this target in all treatments.
Photos – End of growing season
Control
North Side Ripped trees
Double Ripped Trees
South Side Ripped Trees
Tops of Control Trees
Tops of North Side Ripped Trees
Tops of Double Ripped Trees
Tops of South Side Ripped Trees
General View – Un-pruned block
Un-Pruned Trees – 3rd season after grafting