WESTERN AUSTRALIA AVOCADO STUDY GROUP
Minutes from meeting at Russell Delroy’s orchard, near Pemberton
10:00 am till 4:00 pm, Wednesday 18 June 2008
Aim of project
“Make Australian avocado production more internationally competitive”
Main topics of the day
“Canopy management”
Present: (48 + 4)
Growers: Tom, Faye, Tim & Bernadette Backhouse, Sue Bamess, Paul & Maria Bidwell, Bill
and Sam Castleden, Peter & Ron Cocking, Jonathan Cutting, Vin & Liz Farrell, Russell
Delroy & Rob Demetri & Jon Simpson, Tony Fontanini, Mark Ford & Linda Viviers
(Landmark), Jennie Franceschi, Phil & Wendy French, Wil French, Tony Gumelli, Robert
Gwynne, John & David Haynes, Murray Hegney & David Stewart, George Ipsen, Ron &
Maria Kemp, Travis Luzny, Dink, Robyn & John Mathews, Phil & Jan Minchin + 1, Tony
Mulligan, Jamie & Julie Patton, Andrew Scott, Kim Skoss, Richard Stuart-Williams, Tom &
Jocelyn Wilkinson
From AAL: John Leonardi
From Department of Agriculture and Food West Australia: Alec McCarthy and Cengis
Erol (new WA avocado industry development officer)
From Queensland Department of Primary Industries & Fisheries: Simon Newett
John Leonardi discussing canopy management issues with farm manager Rob Demetri
'Whilst every care has been taken in preparing these minutes, Queensland
DPI&F accepts no responsibility for decisions or actions taken as a result of
any data, information, statement or advice, expressed or implied, contained in
these minutes. The views and recommendations of the speakers are not
necessarily endorsed or supported by Queensland DPI&F."
PROGRAM
Agenda
• Introduction by Alec McCarthy and introduction of the new avocado industry
development officer (IDO) for West Australia, Mr Cengiz Erol.
• Discussion of industry issues – Jennie Franceschi, AAL board member for WA
• ‘Why do we need canopy management’ – Simon Newett, DPI&F Queensland
• ‘Canopy management strategies for WA’ – John Leonardi, AAL
• LUNCH
• Overview of the orchard, followed by farm walk – Russell Delroy
• Identification of topic and venue for next meeting – Alec McCarthy
• Report on avocado tour to Chile – Simon Newett
INTRODUCING CENGIZ EROL, AVOCADO IDO FOR WEST AUSTRALIA
Alec introduced Cengiz Erol who is starting as the Industry Development Officer on July 1.
The project has two years to run.
Cengiz Erol,
new avocado
IDO for WA
INDUSTRY ISSUES – JENNIE FRANCESCHI
Biennial bearing was raised as a serious issue for the WA industry – Jennie said she would
table this at the AAL R&D meeting in September.
Jennie encouraged growers to join AAL and to take part in Infocado. Infocado is about
collecting and providing accurate market information. Essentially this entails feeding your
avocado despatch and forecast data into Infocado (run by Joanna Embrey at AAL) and in
return you receive weekly reports from the system. Currently growers who contribute to the
system supply 70% of all avocados to the Australian markets. One of the objectives of
Infocado is to achieve a more even supply of fruit onto the market which will assist in
keeping prices more stable and at a sustainable level. Also by having a better idea in advance
of how much fruit is going to be arriving on the market it allows avocado promotion to be
scheduled when large volumes of fruit are expected.
A focus group exercise was conducted recently to determine the optimum avocado dry matter
level preferred by consumers. The main finding of this work was that customers were
unlikely to come back to buy more avocados if the fruit they just tasted was below 22% dry
matter. Jennie would like to see a regional DM level established.
Quality checks are being conducted in-store in the main cities, these include dry matter and
general quality.
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WHY DO WE NEED CANOPY MANAGEMENT
Simon Newett, DPI&F Queensland
Simon gave an overview of the need for canopy management and outlined some of the
factors that need to be considered.
Please refer to copy of Simon’s MS Powerpoint presentation for details.
There was a comment from the floor that one hectare of orchard can only harvest a maximum
of one hectare of sunlight. Based on this fact the grower suggested that an orchard that was
totally canopied over (with nil light reaching the orchard floor) would capture the maximum
amount of light available.
Other questions
Has any work been done on carbohydrate levels and ways to reduce biennial bearing?
Yes quite a bit has been done but it is a complex subject and not well understood at present.
Refer to the AVOINFO reference database and www.avocadosource.com for information.
E.g. 1. Alternate bearing in the 'Hass' avocado (Persea Americana Mill.), Lovatt, C.J., S.
Salazar-Garcia, S. Paz-Vega, World Avocado Congress IV, Program and Summaries.
Uruapan, Michoacán, México. October 17-22. 44-45, 1999 (AVOINFO reference # 4269).
E.g. 2. The relationship between carbohydrate levels and productivity in the avocado and
impact of management practices (Final report AV033), Whiley, A.W., Horticultural Research
and Development Corporation Final Report AV033, HRDC, 1996 (AVOINFO reference #
3802).
Any recent developments on clonal propagation and new rootstocks?
Dr Tony Whiley is conducting a project funded by industry and Horticulture Australia Ltd
(HAL) to identify and test superior rootstocks. He has discovered some outstanding
rootstocks which are still undergoing testing and if they continue to show promise they may
be released within a year or two. Tony is also undertaking some propagation work in order
to develop improved techniques. Trees grafted to clonal rootstocks have the advantage of
being genetically identical thus giving more uniformity across the orchard; however you need
to be certain of the superiority and suitability of the proposed rootstock for your conditions
before you go to the extra expense of having it cloned. Also it should be noted that certain
rootstocks are suited to certain conditions, so it is not a case of “one size fits all”.
CANOPY MANAGEMENT STRATEGIES FOR WA
John Leonardi, AAL
Please refer to copy of John’s MS Powerpoint presentation for details.
Here are some additional notes covering some of the discussion and questions that arose.
Selective limb removal
When cutting limbs back during using the selective limb removal, can limbs be cut back to
laterals rather than back to the main trunk framework? Yes this is fine.
Important when conducting selective limb removal to cut the limb very flush with the
trunk/major limb – if a stub is left you tend to get more regrowth which then has to be
removed. Also it is harder for a stub to callous over and often the stub will then rot and this
rot may to spread into the trunk.
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Major limb removal
A strategy that re-shapes the tree over a period of 3 years whilst maintaining some fruit
production:
Year 1: Remove one side of the tree row (E side in N/S rows, S side in E/W rows to
minimise sunburn).
Year 2: Remove individual limbs that do not conform to the desired tree structure (being
careful not to break the re-growth from Year 1)
Year 3: Remove the opposite side of the tree from that removed in Year 1 (the regrowth
resulting from the Year 1 prune should now be setting fruit).
Observation that heavy duty hedging of larger trees resulted in far too much regrowth if left
unchecked. Potential use for Sunny?
Repeated mechanical pruning can result in the formation of a dense hedge that limits
penetration of light into the canopy. This can be overcome by creating ‘windows’ which will
also assist with access for harvesters. These ‘windows’ are achieved by selective limb
removal.
Major concern with sunburn in WA
Sunburn was raised by growers as a major problem in WA. The trees can experience a major
leaf fall at flowering and are slow to replace this leaf thus exposing fruit to sunburn through
summer. We would normally put leaf fall at flowering directly down to Phytophthora root
rot but some WA growers blame the leaf fall on low carbohydrate levels in the tree as a result
of carrying 2 crops for several months of the year plus the cold winter. They say that a
decent protective leaf covering does not develop until about February therefore exposing fruit
to spring and summer sunburn. Fruit are susceptible to sunburn after the soft conditions of
winter and spring. Sunburn can occur in late spring and in summer when days occur with
hot, dry easterly winds and temperatures above 35º C (e.g. this happened on Boxing Day this
year; fruit were sunburnt on the eastern side quite early in the morning).
It occurred to us that we should find out if other avocado growing countries with similar
climates to WA have the same problem and if so what they put it down to and how they go
about rectifying it.
We therefore we consulted with various experts around the world including those working in
countries with Mediterranean climates including Chile, Israel and California.
Out of the four replies received two have suggested that we take a closer look at
Phytophthora cinnamomi (root rot) as the cause.
The other two think it may be associated with irrigation practices/soil moisture conditions,
one of these mentions that “crazy” flower (out of season flowering) can be an associated
symptom, the other suggests that the wet season and/or irrigation practices could be causing
water logging and associated death of avocado roots (avocado roots have a high oxygen
requirement) – this would lead to the same canopy symptoms as root rot.
The common thread is that they are all connected to root health. The topic would be a good
one to follow up at a future study group workshop.
Sunburn prevention
“When using kaolin sprays, is there a problem with removing the residue from fruits?”
Yes, it is an issue for Hass. Visible residues on the fruit are not acceptable in the market and
are difficult to remove from rough skinned fruit such as Hass. Surround® (a product sold
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for sunburn protection) comes off smooth fruit such as apples but cannot be removed easily
from Hass avocados. The use of some sunburn products can lead to an upsurge in scale
insects (some beneficial insects are repelled by the presence of sunburn product on the plant
surface upon which they are walking).
“Likelihood of sunburn on exposed limbs as a result of pruning?” General response was
that if timed appropriately, it should not be a big issue as new leaves will hopefully grow to
protect exposed limbs. Alternatively can use paint, or spray-on clay (kaolin - Surround®.
It was suggested that an application of a side dressing of an NPK fertiliser in autumn may
keep more leaf on the tree for the critical period.
“What about sunburn to mature fruit?”
In WA it is best to pick exposed fruit as soon as it is mature, early in the season, e.g. in
November, the Dry Matter levels at this time have reached 25%.
Staghorning/stumping
Cut as low as possible (just above graft). Do whole sections or whole blocks at a time.
Doing alternate rows will only result in rapid regrowth as it “reaches for the sky” when
sandwiched between unstaghorned rows either side. Use plenty of sunburn paint. Mulch up
the prunings and spread around the base of the tree (but never right up against the tree trunk).
Consider the use of Sunny® to get the trees back into production as soon as possible – this
works by temporarily suppressing the vigour of the vegetative regrowth. It is unusual to get
fruit from stumped trees in less than two years; sometimes it takes up to four.
Timing of stumping? As soon as possible after harvesting. In the SW of WA probably about
November.
Hass phenological cycle developed from observations made in the Pemberton area – it
shows that the spring leaf flush is not mature till the end of February thus leaving fruit
exposed for two to three months if a major leaf fall occurs at flowering time in Oct-Nov.
Scoring
Observation that after scoring, branches produced much less follow-up leaf development
than non-scored branches and that this led to sunburn problems. Even a year post-scoring
some 10% of branches scored have not recovered.
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Is the timing of scoring that important? Yes, usually it is done in late autumn, after the
spring flush has hardened and hopefully some good root development has occurred.
Observation that a similar result was achieved from using Sunny® alone, compared with
scoring in May in combination with the use of Sunny®.
Could scoring of branches carrying a heavy crop be used to induce a follow up flowering and
fruitset to try and reduce the biennial bearing tendency? Not sure, but worth experimenting
with.
The observation was made that removing branches for canopy management during an ‘off
year’ could result in even stronger vegetative regrowth and another ‘off-year’, then this
followed by an even stronger ‘on-year’ in year 3 – thus maintaining bienniality.
Observation that tip pruning 0.5 m of growth in late autumn worked well for a few years
but eventually resulted in too much regrowth and the subsequent shading resulted in reduced
yields.
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FARM WALK
The orchard consists of 1 000 trees planted in 1988 and another 40 000 planted between 1999
and 2002. All are ‘Hass’ and most are on ‘Hass’ rootstocks grafted in their own nursery.
They are on a spacing of 7m x 3m (476 trees/ha) and when this spacing was decided the
thinking was that mechanical hedging was the way to go. They also grow kiwi fruit and
tamarillos (tree tomatoes). The orchard has three permanent employees.
The orchard had a severe frost in June 2006 which destroyed the crop hanging on the tree and
killed the flower buds for the next so the current crop is the first since.
General view of the 6 to 9 year old trees
Soil & nutrition
Soil is a gravelly loam called a ‘Karri loam’ and the soil pH is about 5.8.
Leaf analysis is done every May to help determine the nutrition program.
They have some difficulty maintaining sufficient levels of zinc and boron.
Most nutrition is applied throughout the year using fertigation.
Mulching
All trees were heavily mulched from Day 1 with composted Jarra bark spread 200mm thick
in a strip 1.2m wide either side of the tree. This mulch has a ‘half life” of 3 years. Jarra bark
must be composted or at least allowed to age to get rid of the tannins. Materials were added
during the de-barking operation to aid breakdown. Where the composted Jarra bark was
added at a rate of 400m3 per hectare this one-off application lasted long enough till the tree
was generating its own mulch through natural leaf fall.
Murray Hegney said that they have found that Jarra bark is good too but they did have an
incident where fresh un-aged bark was applied in error and trees were poisoned - turning
yellow and nearly dying. Eventually the phenolic compounds were leached out of the root
zone and the trees are now starting to recover.
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Compared with pinebark the Jarra lasts longer and in addition it is easier to find healthy roots
under Jarra bark compared with pinebark.
When applying heavy rates of compost it is important to monitor nutrition closely as
sometimes mulches can have a large draw-down effect on available nitrogen. If this happens
more nitrogen will need to be applied.
If the bark is simply going to be aged (rather than composted) it needs at least 18 months in
the open and this must include a good winter rainy season to leach tannins and other
potentially toxic compounds out of the bark.
All trees on the orchard are mulched heavily with composted Jarra bark soon after planting
Pests and diseases
Generally no sprays for pests or diseases are applied except phos acid against Phytophthora
root rot. They have been applying 1 spray per year but plan to apply 3 to 4 per year from
now on. Timing will be from May through till July.
Pollination
200 beehives are brought in each year, which is equivalent to just over 2 hives per hectare.
Harvest
The harvest season runs from November onwards. Currently fruit is picked from standing on
the ground and with the use of ladders. They used to pack on the farm but now send their
fruit to the packing shed in Donnybrook which operates for 12 months of the year packing
apples and stonefruit as well. Avocados are marketed direct to Coles and Woolworths.
Irrigation
There are two dams on the property that supply the irrigation needs via one 35 L/hr sprinkler
per tree. Water use in a typical year is about 8 ML/ha/year. Irrigations are scheduled
according to information from tensiometers and evaporimeters. At times a high frequency of
irrigation is required.
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Left: good set on an exposed branch which illustrates the importance of good exposure to light for flowering and
fruitset. Right: Russell Delroy discussing aspects of the orchard
Canopy management
Young trees were mechanically tip pruned in about May each year for about the first 6 years.
Flowers developed on the remaining shoots below the cut.
Russell is not sure yet of the canopy management approach that they will as the trees get
larger. One possible option is to remove every second row if a system to do so can be found
that does not require too high a labour input.
Their older block was staghorned in 2005 to chest height by a contractor using a forestry flail
mulcher mounted on an excavator arm. This machine pulverized the foliage and wood into
chips that could be used for mulch, then the remaining branches were cleaned up by cutting
off the splintered ends off with chainsaws – removing about 30 to 60 cm. This was far
cheaper than doing the whole process by hand. Russell considers that the mistake they made
was not following up with PGRs to contain the regrowth.
Out-of-season flowering
Some “crazy” flowering occurs out of season and this may result in some fruit being set in
winter. This fruit from this flowering is round in shape and has smoother skin.
Out of season “crazy” flower (left) in autumn results in some fruit set. The fruit (right) tends to be round
in shape and relatively smooth skinned.
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These trees planted in 1988 were staghorned in 2005. Regrowth has been very rapid.
Biennial bearing
Last year there was a light crop but the trees flowered heavily and are now carrying a heavier
than normal crop. There are not many flower buds present now but they should be sufficient
if conditions are warm and sunny.
Machinery
Tractors and other machinery on this farm are low-set in order to fit under the kiwi fruit
hoops which are 6’ high.
Weed control
The centre of the interow is mown and if necessary the under-tree strip is sprayed carefully
with Roundup.
NEXT MEETING
When:
Wed 24 September 2008
Time:
10 am
Where:
To be advised
Main topic: Soil Health
ACKNOWLEDGEMENTS
Very many thanks to Russell Delroy, Rob Demetri, Jon Simpson and Tanya for all their hard
work to prepare for and host the meeting and for the very interesting farm walk. Thanks to
John Leonardi who was the main guest speaker, and Alec McCarthy WADA&F for helping
to organise the day.
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APPENDICES & ATTACHMENTS
• Grower feedback from the meeting
• ‘Overview of canopy management’ Simon Newett, Queensland DPI&F, Nambour
• ‘Canopy management for WA’ John Leonardi, AAL
• ‘Positive Points’ orchard management self assessment
• AVOMAN and AVOINFO order form
Simon Newett,
Queensland DPI&F
PO Box 5083 SCMC
NAMBOUR QLD 4560
Email: [email protected]
Phone: 07-54 449 619 Fax: 07-54 412 235
Alec McCarthy
Horticulturist
Department of Agriculture and Food WA
PO Box 1231, Bunbury WA 6231
Email: [email protected]
Phone: 08-9780 6273 Fax: 08-9780 6136
Mob: 0429 372545
Gengis Erol
Avocado Development Officer
Department of Agriculture and Food WA
PO Box 1231, Bunbury WA 6231
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Appendix I
FEEDBACK FROM THE DAY – FOR USE IN PLANNING FUTURE MEETINGS
Your current farm practice:
What best describes your current canopy management practice? (tick the box for the most
appropriate description)
Trees too young to be pruned……………………………………. 2
Trees need pruning but not addressed yet……………………... 3
Ad hoc approach - when resources and time permit…………. 2
Experimental approach, still undecided on best method……. 5
Program followed but needs reviewing………………………... 4
(tree/row removal of orchard to be replaced after 18-20 years)
Proven program followed ………………………………………. 0
Today’s workshop:
1. How useful did you find this workshop? Please circle the most appropriate description.
Not useful
2.
Fairly useful 1
Useful 6
Very useful 7
Extremely useful
List the 3 most useful things that we did today and why?
•
•
•
•
•
•
•
•
•
Orchard walk, networking with others.
Presented C.M options, gave opportunity to discuss & share ideas.
What not to do re pruning/canopy management, some more info re alternate
bearing problem.
Orchard walk, canopy management- scoring etc biennial baring, nutrition program
re carbohydrates issues.
Discuss canopy management for future, looking at & discussions in orchard,
meeting other growers.
Canopy pruning.
Saw canopy management techniques in action, say a mulch spreader, interesting
discussion with other growers.
Talks with other local growers, listened to excellent presentations, listened to
excellent discussion.
Open forum discussion, presentation of canopy mgmt systems (this must be more
focused towards the SW of WA, I am getting sick of hearing about what Qld
growers are doing.), field walk & discussion.
3. Did you feel able to participate?
No
A little 1
Some 3
Many chances 8
Every chance 2
4. Have you established new contacts today and/or had beneficial discussions with others?
Yes 14 No
5. Have you learnt something new about avocado production and/or fruit quality today?
Yes 11 No 1
6. Has what you learnt today made you question your current farm practices?
Yes 9 No 4
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7. Do you think, from what you learnt today, you will make a change to your farm practice?
Yes 7 No 5
If yes briefly describe:
•
Make more effort to prune.
•
Pruning “windows”, scoring.
•
Pruning program.
•
Motivated to get into pruning.
•
Evaluate cincturing.
•
Phos acid canopy timing, Qld based advisers don’t seem to understand the extremes of
climate in Pemberton, from severe sunburn to hot & cold winds, frosts & extremely
heavy flowering & leaf loss.
8. In running the day, what could we do better?
• 2 microphones – 1 for audience.
• Turn the temp up a little.
• Done very well – thankyou. The canopy management presentation was excellent..
• Start on time.
• Not a lot.
• Well done.
• Good.
• The day was quite ok however the food was a bit light on.
9. Any other comments?
• Well done Simon & John.
• Our plantings are only 5 years old so all ideas are welcome, we are not changing
much but implanting new ideas all the time.
• 2 Microphones so that questions can be heard.
• Victualling very good.
• As organic/BD growers – some material is not relevant at all – different approach.
• Please give more notice of study days (I had to leave earlier because of a prior
unalterable engagement).
• More work needs to be done in the sw of WA as this area’s Avo production is
expanding rapidly. Some discussion on the benefits of group marketing under one
brand could help.
Minutes of last meeting
1. Did you receive minutes of the last meeting?
Yes 9
2. Did you read them?
Yes
No 4
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3. What did you like about them?
• Very informative
• Good reminder of the day with backup data to follow up
• Good detail, good summary of issues discussed, good photos.
• Hopefully a good discussion of the field day (which I missed).
• Fairly detailed which is good.
4. Any suggestions to improve them?
• Keep up the good work (x2)
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