Kia ora, welcome to our Avocado Quarterly Newsletter

eNews Avocado 2nd Quarter 2022

Leigh Neilson

Hello all,

When asked to write this piece I thought about what three issues are most important to growers right now.

A. Operating costs both controllable within the orchard gate and largely uncontrollable outside the orchard gate.

Many “Rural” CEO’s and General Managers talk a lot about sustainability as it relates to production. Having attended a Fieldday at Opotiki recently, led by Jonathan Cutting, on “Managing Orchard Costs” it dawned on me that after last season the OGR is not sustainable financially. It would be good to see our industry leaders and partners talk and actually support growers through these difficult times rather than just keep increasing operating costs to maintain their profit margins. Growers need to be increasingly transparent as to GAP etc but are our partners also practising this discipline?

One thought I had was that our partners-Exporter & Packhouse, for example, may consider arranging on behalf of growers, bulk purchase discounts for run of the mill sprays and fertiliser rather than growers paying “retail” individually.

B. The Science

Currently, we as growers, have three entities, ( NZ Avoc, Avoco, Packhouse Reps) largely individually telling us and having fielddays around many of our orchard practices. That’s commended for sure, BUT it is starting to become somewhat confusing about who to follow on what subject.

In the days of the GROWERS MANUAL (first published in 1997), the way forward was simple as there was one reference point to follow. These days there are many directives from different sources on sprays, Fert, pruning, etc.

It would be great if the Industry could consolidate the science and make it less confusing for the grower. Of course, Zespri and Fonterra would be ideal models to emulate in this regard. Fair to say that many of their adopted standards were set in place after very poor return periods.

C. Trevelyan Avocado Growers Ltd

On 23rd June the Directors of this new entity met to transition from the previous Shed Committee entity.

I urge all growers to support the way forward through this new company, as the main purpose is to represent all growers in a sounder and more structured manner

There are to be nine grower directors and three Trevelyan directors. Ashby Whitehead is the Interim chairman

Watch this space…

Roll on more sunshine!

Daniel Birnie
Avocado Manager

The price of avocados from consumer to grower

We have just completed a piece of work on the price of avocados from consumer to grower.  We started this work after some questions were raised from growers, questioning why the price is $2 per piece of fruit in the supermarket, yet growers only receive a fraction of that.

The table below has the price a consumer pays in the top row. Below that is waste, and at certain times of the season, this can amount to 8% of the avocados sold in the supermarkets. Below that is GST, and then the supermarket costs and margin.  Within this there will be ripening costs, transport to the store, and their operational costs.

The sell price to supermarket are what BayFarms sells fruit to them for, and below that are costs associated with the NZ Avocado levy, transport to the supermarket distribution centre (DC), BayFarms (BF) commission, and our packing and packaging costs (which are fixed regardless of the fruit value).

One comment I have is that at certain times of the season, the price in the supermarket does not reflect the grower’s return. It seems that the supermarkets periodically decide to take a bigger margin. For example, recently we saw fruit being retailed at $2.29 a piece, however, the coolstore door return was only $0.82 and the OGR was around $0.55 per piece.

The exercise has shown that both supermarkets and growers benefit from the higher price in the supermarket. This will be offset by lower demand as the prices rises.  As growers, we really need to be making $10 per tray out of the local market through the height of supply, and higher in the shoulder seasons.

Supermarkets have been in the spotlight lately, and there is discussions of new regulations that would make the industry  more competitive.

Any scrutiny of the supermarkets is welcome amongst growers; however, we are not sure what the final outcome will be.  They are similar to banks in a way, we need them to be profitable and be well regulated, however, we also want them to be fair and reasonable with their consumers and their suppliers.


Katherine Bell
Grower Liaison Representative

Over the last couple of weeks there have been several field days where I picked up on some interesting points:

  • At the NZ Avocado Field day, I was interested in the point made that three and four-year-old wood is the best flowering wood, and it’s important to make your pruning decisions around this. Therefore, it is paramount to look after this wood, especially when it comes to mites. Defoliation will cause a setback in recuring crops for not just the coming spring.
  • At Dr Alison Matthews talk on 6SM I was interested to learn that Western Australia has a different seasonal trend in mite levels to New Zealand. They get a small spike in mite populations in autumn, no mite issues in winter, and a large spike in spring. We tend to have populations increasing steadily from autumn right through winter, where we need chemical intervention to minimise the increase so that we don’t lose control of the mites going into flowering (spring).
  • At the orchard cost workshop, we discussed what each orchard spent on their spraying. We considered how the chemical was the biggest cost component and that making the correct chemical selection was important (if you are unsure about what chemical to use please contact your rep). Chemical availability was also talked about, due both to the increase in withholding periods, and chemical companies looking at discontinuing supply because of the EPA reviewing neonicotinoids.

Considering all this information and the questions I have been receiving from growers around their increasing mite populations, and the queries about what to spray at this time of year, I thought I would highlight one of our chemical options.

Etoxazole sprays (such as Paramite or Etoxamite) carry out translaminar activity and break the mite’s lifecycle. Being translaminar means the spray will move through the leaves to where the mites are feeding on the underside. This spray is effective in all stages of the mite lifecycle and kills the eggs.

Etoxazole will sterilise any adult females and prevents moulting in larvae and nymphs. With its limited effect on adult mites, we recommend adding either an Abamectin (e.g. Avid) or Milbermectin (e.g. Mit-e-Mec) for large infestations. You will find with just adding Etoxazole that adults will be present for a couple of weeks after application. They will still be feeding so this is where we recommend applying Etoxazole when mite populations aren’t too high.

The spray should be applied to a dry canopy at 35ml per 100L of water and you are limited to one application per season. Etoxazole is soft on beneficials and since the spray is the only one in its class, there is no risk of resistance when using other miticides. This makes it an important part of our rotation programme to prevent resistance.

Recently, the withholding period for Etoxazole was reduced from 63 days to 56 days for Asian markets. It is best applied when nymphs are in their early stages of development. This is generally in winter before an increase in adult populations. Control occurs within seven to fourteen days after application and the spray has a residual effect for up to five weeks. If you are planning to harvest early in the export season, we will need you to remain market-compliant, so please contact your rep in regard to spray options.


Jonathan Cutting
Avocado Technical Manager

Avocado whole tree mineral nutrition

I recently attended an Avoco presentation entitled “21/22 Nutrition Update”.  The content covered some basic plant nutrition principles and then went into some depth on tree needs based on nutrient replacement theory, fertiliser timings, and mineral nutrition as affecting fruit quality.  My experience is that you always learn something from presentations.  Afterwards, when reviewing the presentation, it struck me that a great deal of the presentation focussed on high-level fruit quality outcomes which are moderated by mineral composition.  I would like to build on what was presented and cover other drivers for nutrition such as yield, fruit size, tree health, cold tolerance, and vigour management.  There is no question that whole tree nutrition is complicated and some compromise and balancing is required to achieve the complex outcomes we want.

To start I would like to take a step back and consider why we do apply inorganic mineral fertiliser nutrition.  The chemical compounds required by living organisms for growth and development are termed nutrients. The nutrients required by higher plants, such as the avocado tree, are exclusively inorganic.  There are 20 or 21 essential nutrients (including carbon, oxygen, nitrogen, hydrogen, phosphate, potassium, etc).  This makes plants different from other organisms, from mammals to many species of microorganisms, which additionally need organic compounds (made by plants such as sugars) to provide energy.

Plants absorb light energy from solar radiation and convert it to chemical energy in the form of organic compounds (sugars), whilst at the same time taking up mineral nutrients to provide the chemical elements essential for the growth and the production of organic compounds. When inorganic nutrient supply is limited, out of balance, or in excess, plant performance is impacted.  Most often we deal with the nutrient supply by adding additional nutrients, generally to the soil, thereby improving the plants ability to grow and develop.  Understanding what is needed, when, and how much to supply is the science of plant nutrition.  Fertiliser science is the packaging of nutrients into forms that can be applied to the soil (and sometimes directly to plant leaves) and understanding the implications of the nutrients on soil biology, soil physics, and soil chemistry.  It’s a very confusing science with plenty of conflicting philosophies, methodologies, commercial interests and technologies.

We apply inorganic nutrients (such as nitrogen or potassium) at two levels, the first to avoid deficiency, and the second to help the avocado with “environmental plasticity” which is the ability to adapt, grow and thrive outside the plants evolutionary environment (which is a mesic, subtropical rainforest environment).  For example, growing in coastal frost-free temperate environments (like New Zealand) to semi-deserts Mediterranean environments (like California, Chile, or Western Australia) to highland tropical environments (like Kenya and Mexico).

Avocados in New Zealand do require additional nutrients.  Generally, we are dealing with well buffered, high carbon, fertile soils but deficient in certain important elements such as zinc, magnesium, and boron.  There are times of the year when temperature-driven mineralisation (organic release of nutrients such as nitrogen for example) is in excess of need and other times of the year when the soil shuts down and very little mineralisation occurs.  Compaction, drainage and excess phosphate are often compounding problems.

Applying fertiliser is a way to “drive” or ‘force’ the tree to change physiological biases that exist in the tree and that impact tree performance in commercially negative ways.  Here the focus could be to:

  • Managing tree “health” especially root health
  • Changing the balances between vegetative and reproductive growth
  • Maximise canopy health and minimise short leaf life
  • Reduce leaf photo oxidation
  • Increase the amount of sylleptic shoot growth
  • Minimise late summer and autumn shoot flushing
  • Increase fruit size
  • Deliver good postharvest fruit quality
  • Maximise postharvest shelf life

And the  second tier of considerations are:

  • Maximising biological diversity in the orchard soil
  • Shifting the fungal to bacteria ratio to give a fungus rich soil
  • Improving soil physics
    • Drainage
    • Reducing compaction
    • Porosity
  • Improving soil chemistry
    • Addressing soil pH and nutrient availability
    • Eliminating trace element deficiency, especially zinc and boron)
    • Maintaining cation balances in the soil with a focus on potassium calcium and magnesium (base saturation)
    • Increasing soil carbon
    • Increasing soil cation exchange capacity (CEC)


Nitrogen is the key “driver” element in the nutrient toolbox and requires special attention.  It is key in protein synthesis and drives whole plant vegetative growth (leaves and shoots).  It is a key driver of all enzymatic processes in the plant, for example chlorophyll regulation of both its production and breakdown and another example being oil production from sugars in the fruit which is then stored in ideoblasts in the fruit flesh.  High nitrogen is also assumed to play a role in fruit quality.  High soil nitrogen suppresses beneficial soil fungi and alters the soil bacteria to a fungal ratio in favour of bacteria.  Nitrogen is heavily involved in the soil carbon cycle.  Too much nitrogen also affects the uptake of other nutrients, mostly negatively! (see Mulders interaction chart below).

Fig 1.  Mulders Chart

Based on 25+ years of reviewing leaf analysis results, it appears that to maintain a leaf nitrogen target of 2.7-2.8 % nitrogen we need 80-130 units of nitrogen.  Most fertile, high-carbon New Zealand soils have plenty of plant available nitrogen in the summer from organic mineralisation and fixation and we do not need to apply it then.  Other periods of higher nitrogen need are:

  • Early spring through early summer (September through to the end of December) to balance the reproductive to vegetative balance and ensure flowering wood for the following season. This is a delicate time with fragile balances. We are looking to provide between 50 and 60% of our annual nitrogen need at this time.
  • Late summer and autumn (mid-March through May) when all flushing should be underway and almost complete. The goal should be to “load “ the leaves with nitrogen to maintain enzymic activity and, in older leaves, prevent early chlorophyll degradation and support good flower bud growth through the autumn and winter. We are looking to provide about 30-35% of the annual nitrogen needed at this time.
  • Mid-late winter (June through to the end of July) to maintain leaf quality and minimise photo oxidation and premature leaf drop. We are looking to provide about 10-15% of the annual nitrogen needed at this time.


Most New Zealand soils have had too much phosphate thanks to heavy phosphate applications on grass pastures last century. Too much phosphate is associated with reduced calcium, iron, zinc, and potassium uptake. In the literature, high phosphate uptake is also associated with poor fruit quality.  There should be no reason to supply phosphate to most New Zealand avocado orchards.  Our soil target is between 25 and 40 Ohlson units.


Calcium nutrition is both difficult and very tricky!  It is largely immobile in the soil and if the soil is not tilled it moves down in the soil in mm per annum.  Key sources of calcium are liming products (neutralising materials) such as calcium carbonates or hydroxides, calcium sulphate (gypsum), and dissociating calcium as found in products such as calcium nitrate.  Calcium makes up the largest fraction of the soil base saturation.  Liming products have a large impact on raising soil pH which in turn determines the solubility of all nutrients in the soil.  A soil pH of around 6.5-6.8  maximises nutrient availability.


Nutrient timings and multiple applications

This is a difficult topic.  We are trying to cover a lot of bases, some conflicting.  To some extent most plant nutrition, once the deficiency has been addressed, is aimed at enhancing or suppressing the natural plant phenology (growth in response to season).  A great way to consider this is to look at the avocado phenology chart and work out what you want to manipulate either up or down.  The phenology chart below (developed by Avoco) is a very useful tool for doing just this.

Targeting just nitrogen, calcium, boron, zinc, and potassium nutrition is challenging enough without the complications of soil carbon, leaching losses, biological diversity, and environmental stewardship.  My guide to growers is to:

  • Have an annual fertiliser programme based on a certain yield expectation, say 15 tonnes. The development of your fertiliser plan should be undertaken by an experienced professional with an understanding of the avocado phenology.  As it will be a programme for the coming season be prepared to make multiple revisions and changes in response to impacts like fruit set, weather conditions over summer, etc
  • Annual nutrient use guidelines are:
    • nitrogen 80-120 units
    • phosphate 0-5 units
    • potassium 100-200 units
  • Split highly active fertilisers like nitrogen into multiple applications to minimise leaching losses
  • Time applications in advance of need taking into account solubility, rainfall, and the lag period affecting the availability
  • Try to use simple straight fertiliser whenever practical as it prevents the overuse of certain nutrients in compound blends
  • Be aware that zinc applications need to be spatially separated from phosphate (if phosphate is high in the soil)
  • Apply liming products twice annually in late winter and late spring
  • If using compound fertilisers use ones with the lowest possible phosphate
  • Some nutrients require white non-suberised roots for uptake
  • Mulching and improving soil health with improved nutrient uptake
  • Soil micro organisms improve nutrient cycling and movement through soils
  • Irrigation can improve fertiliser outcomes
  • Good root health is essential for efficient and effective nutrient uptake
  • Be aware of the impact of some herbicides on soil and root health
  • Understand that the oil in the fruit comes from sugars made in the leaf and transported as sugars to the fruit where it is synthesised into oil. Remember – the canopy is king!

In summary, this article is not to teach anyone how to develop nutritional programmes.  Rather its purpose is to assist growers with understanding some of the interactions that need to be considered when putting a programme together, what type of questions to ask your fertiliser consultant and when to think about programme revisions.  Fertilising your trees is an important piece in the “growing avocado” puzzle.  However, it does “interlock” with other pieces. Being aware that soil health, harvest strategy, pruning, root rot management, crop load, irrigation, soil tilth, and porosity, etc. all have an influence of nutrient uptake. Additionally,  allocation enables growers the time to  focus on their orchard inputs that collectively strengthen and improve the orchard performance.  Healthy leaves and roots are essential for fruit yield and quality.  It would be really helpful if growers understood the multiple interacting functioning physiological pathways necessary to turn good plant nutrition into lots of high-quality, robust fruit.  It might even change where and how they invest inputs in the orchard.

Stuart Jennings
Avocado Orchard Manager

Orchard Management

Trying to control thrips on orchards this autumn has been a struggle for most growers, and our managed orchards are no different.  We are now monitoring mite levels carefully on orchards and will apply Etoxamite if levels exceed 20% in either the low, medium, or high fields.

On one of our orchards that has young trees, we have applied Thermomax for frost protection, however, this winter has been one of the warmest on records. Our kiwifruit team is always monitoring chill units (the number of hours below seven degrees) in orchards, and this past winter has been the warmest of the past five.


Soil and leaf testing are now complete on all of our managed orchards.  We are now preparing new management plans and budget reviews with our growers, and the GAP audit will be taking place with Trevelyan’s staff which covers off all our managed orchards in one audit.

Pictured below is one of our young trees planted late last season in a managed orchard in Katikati.



Zara Marra
Local Market Manager

Local Market Update

As I look back on the 2021/2022 season, I breathe a sigh of relief.

The domestic season (1st June 2021 – 31st May 2022) finished 1.26M TE’s up from the previous season.  The increased volume brought downwards pressure on returns, there were continuous issues with crates, and all of this was compounded by COVID-19 level restrictions…. just to name a few.

Class 2 smalls and Class 3 fruit were diverted to process for the majority of the season with an aim to preserve the Class 2 pools. We were fortunate that our processors agreed to receive additional volume.  Although the increase in process volume has caused delays in payment on Class 3 pools, this option was more sustainable and provided a return to the pool, which outweighed the cost to compost fruit.

Crate shortage was a major issue. North Island retailers have a restricted supplier preference for produce. The shortage impacted our ability to pack to demand, especially during the summer fruit period, and post-export. There were several points post-export where we were forced to delay harvest/packing until adequate volumes of packaging were received.

Season transition. With new season clearances, we have begun the transition from the old to the new season. The late season volume has meant a smooth transition for those markets still accepting both new and old, without jeopardising value.

With food prices increasing and a 10% increase in fruit and vegetables over the year (May 2021 – May 2022), consumer uptake of produce overall has been slow but consistent.

The 2022/2023 season looks promising. Volumes are forecasted to be down 30% and export is looking good.  With the growth in consumer demand vs supply, we are expecting to see upwards pressure on returns in comparison to last season.

Regenerative Horticulture

Regenerative horticulture is a rapidly evolving topic so it’s good to review where things are at in this space and how closely it is linked to sustainability progress.

The regenerative approach is gaining momentum

Food companies across the globe are setting ambitious goals to adopt regenerative practices across large areas of land and to store significant amounts of carbon in the soil.

McCain Foods, one of the world’s largest makers of frozen potato products, has pledged that as of 2030 it will only be supplied by farms that follow regenerative agriculture practices, as part of ambitious plans to help address climate change. McCain’s other targets relate to a reduction in carbon emissions and making all of its packaging compostable, recyclable or reusable. McCain’s intention is to help growers by opening three ‘Farms of the Future’ around the world by 2025.

Closer to home, the New Zealand Merino Company has launched the world’s first “regenerative wool platform”.  The company has signed 167 farmers up to the programme which provides assurance to customers that the wool they are buying is farmed according to an “index of regenerative farming practices”.

With regenerative practices representing an opportunity to store more and emit less carbon, as well as improve water quality outcomes, the increasing movement in this direction is no surprise.

Regenerative horticulture is more complicated than it sounds 

All this sounds great in theory, especially for those sitting behind a desk making policy decisions and setting targets. For the growers out there doing the work, it’s a different story.  There are dozens of things to consider when making a regenerative transition including:

  • Types of cover crops that make sense for your soil type, weather, and location
  • The variability in the soil characteristics of one block
  • Cover crop survival rates in your orchard
  • How your neighbours will react if you grow cover crops
  • The impact changes will have on productivity

At the moment, business as usual without conservation practices seems to be working out just fine for most growers so finding the motivation to change can be difficult.

Progress is starting to occur

Despite the challenges, where there is a genuine commitment to understand and realise the benefits of regenerative horticulture, progress is starting to occur.

At the end of June 2021, Trevelyan’s hosted a well-attended Regenerative Field Day with expert Daniel Schurmann from Biologix.  While the discussions around soil chemistry quickly became complex, the was plenty of interest in looking at soil conditions and worm counts in an existing conventional kiwifruit orchard that is considering a transition to more regenerative practices.

In November 2021 the Zespri Organic Fielday visited Leighton Oates’ regenerative organic kiwifruit orchard development at Omanawa.  Having started with a greenfield site that had previously been used for dairy grazing meant the soil organic matter started around 15%, rather than 1-3%.  As well as storing carbon, high soil organic matter also increases water retention.  Discussions included the consideration of cover crops, the need for weed strips, the fungal content of compost and the use of seaweed and fish supplements.

Zespri and T&G Global are teaming up with Plant & Food Research and other industry partners on a new project to research, develop, define, and promote sustainable and regenerative horticulture practices within the kiwifruit, apple and berry industries. The project is partially funded through the Ministry for Primary Industries’ (MPI) Sustainable Food and Fibres Futures Fund (SFFF).

The first year of the project, is currently underway and is focused on conducting scientific research on what is known about regenerative practices. A recent survey completed by the growers has revealed the drivers for regenerative horticulture, please see the results below.

Market analysis has also been undertaken to better understand consumer perceptions and drivers.

Where do avocados fit in?

Regenerative horticulture aligns well with many growing practices used in the avocado industry.  Some growers are already trialing cover crops to support the health and pollination of their avocado trees, keeping external inputs like sprays and fertilisers to a minimum or not using them at all.

The regenerative mixes contain different species of plants that have different roles in the orchard:

  • Some have big tap roots to break soil compaction.
  • Some fix nitrogen and make it accessible to the avocado tree.
  • Some provide a safe haven for beneficial insects like steel blue ladybirds which eat thrips.
  • Other flowering plants bring in bees to the orchard which is great during pollination and/or bring in other beneficial insects.

Other regenerative practices include keeping bees (to support pollination) and guinea fowl (pest control) in an avocado orchard.

Change is needed

However you feel about regenerative horticulture, it is clear that change is needed to address critical environmental challenges such as climate change and water quality. The avocado industry needs to understand, acknowledge, and address its environmental impacts.  Regenerative horticulture presents an opportunity to make meaningful changes to address these impacts.



Alistair Niven and Carol Palmer – Pakari Orchard

Where are you based and how long have you been growing kiwifruit/avocados for?

We are in Wharawhara Road, Katikati and have been here growing avocados for 2 years.

What do you enjoy most about your job/what’s been the biggest highlight?

Working with the trees is enjoyable/frustrating as they behave and yield across the spectrum each year, the first pick and watching the pack was a real highlight seeing the hard work going into trays for export.

What has been the biggest challenge of being a grower for you?

Reducing costs as revenue evaporates but ensuring the trees get what they need to yield to the maximum.

If you weren’t a grower what and where do you think you would be?

An owner of a chateau in the South of France operating an Air BnB.

What’s an interesting fact most people don’t know about you?

We knew nothing about avocados before buying and brought our orchard on a recommendation everyone loves avo on toast…little bit spontaneous.


Colleen Phillips – Avogreen Pest Monitor

Tell us a bit about yourself and your background.

I have been living over in Otamarakau near the coast for 7 years. My husband Shayne and I developed our 1.7 ha Avocado orchard ourselves. I have a huge interest in growing avocados and believe they are an amazing  fruit for your health. Some of my family have been in the avocado and orange industry for many years and I am also enjoying following that exciting path.

What attracted you to working at Trevelyan’s?

As we were already a Trevelyan avocado grower, our Trevelyans Representitive Ann Partridge made us feel so welcome to be a Trevelyans grower, that she inspired me to want to become part of that team.

What is your role and what does it involve?

I am a Trevelyans Avogreen Pest Monitor. My role is to monitor avocado orchards in the Bay of Plenty including Opotiki. I monitor a range of pests that will help the grower to determine what management is required to keep pest levels under their thresholds and help to improve fruit quality.

When you’re not at work what do you like to do?

I love to spend time with my 7 grandchildren. I love wining and dining with the love of my life and I really love fishing in the Coromandel.