In this Newsletter
Walnut Drying Field Day
Walnut Sugar Syrup
Social & Blight Spray Forum
The Promise – A Summary
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Basil and Trudi Meyer live on Telegraph Road, it’s long and straight, typical of roads on the Canterbury Plains where they farm. When you visit them you don’t realise that near the house there’s something lurking on the top of a shed.
It’s a substantial solar system that they’ve had for seven years.
Trudi writes about it below.
Ever since moving to Canterbury in 2009 we were looking at ways to enhance our environment. This included looking into alternative energy for our walnut orchard. We gathered a lot of information and contacted plenty of experts.
Considering that our highest use of electricity is in Summer, when (normally) the sun is shining, and we need to use our irrigation to keep the walnut trees and also the grass on our beef block growing, we decided to look into the use of a solar energy system.
In September 2013 we had a 10kwp grid connected solar system installed at the cost of just under $29,000. Consisting of 40 panels and as our deep well pump is running on 3phase power, we also installed 3 Enasolar inverters.
As 10kw is not enough to produce all the electricity needed (our pump is 24kw), grid connected was the only way to go, but this means that when there is a power cut (shutdown), the inverters will shut down to stop any electricity being fed into the grid (for safety of the electricians working to fix the faults). As the price power companies are willing to pay for excess power fed back into the grid keeps going down, we have been looking into battery banks that would allow us to use any surplus electricity produced to be stored and used as needed (e.g. at night for house consumption, etc).
Unfortunately the costs of batteries and their efficiency/lifetime expectancy are not satisfactory yet, but we expect that over the next few years this will change/improve once more power storage options become available.
We are very happy that we have made the step to solar energy, but it also has the draw back that the sun is not shining 24 hours a day. So we have been recording wind speeds for the last 3 years.
A specialist in alternative energy production has been looking at this data and is giving us information of appropriate wind turbines, their efficiency, costs etc.
A work in progress!
Back to our solar system: from 2014 to 2018 the electricity produced from our solar system has been between 13,522kWh and 14,791.29 kWh/year. This depends on the sunshine hours per season.
From this we have used on our property between 10,044kWh and 7,551kWh/year
Considering a kWh price for consumption of own energy produced at 30cents (approx. price of electricity) this equals an annual saving of between $ 3,013 and $ 2,265.
With grid exported energy (sold to power company @ 8 cents/kWh) between 5,600kWh and 6,100kWh/year this equals between approximately $ 448 and $ 490/year.
With annual savings and income of around $ 3,100 this solar system will be paid off after 9 years.
When we started with solar the grid exported energy was paid @18 cents in winter and 10 cents in summer but now, we only get a flat rate of 8 cents/kWh.
Basil and Trudi Meyer
For more information contact Basil or Trudi on 03 317 8130
3 Enasolar inverters.
Trees look different from a drone. One Lone Meyric amongst Rex.
A review of theory and practices by Dave Malcolm.
Just before harvest this year Southern Seeds Technology (SST) gave notice to walnut growers, that they would no long be able to dry walnuts. This left quite a few growers looking for alternatives for drying their walnuts. Fortunately, some larger growers offered their drying facilities.
As a consequence, as the field events coordinator at the time, I organised a field day on walnut drying, to let growers learn about setting up their own walnut drying facility. In this article, I will report on the drying facilities of the three properties visited and also background some theory behind walnut drying.
Firstly, the theory. I had a look back at an article by David McNeil called Improved Management Practices of Walnut Quality Factors under Grower Control, available from the Internet and our WIG website and also a presentation from Lincoln University scientist, Leo Vanhanen to NZWIG members back in 2016.
Walnut drying is a crucial step in producing saleable walnuts. If nuts are not dry enough, moulds and kernel darkening occurs. If walnuts are too dry growers receive less per kilogram for their crop. Also, the kernels become brittle and during cracking more pieces and fewer half kernels are obtained. There are two ways of measuring moisture content of walnuts, shell and kernel and kernel only.
The shell and kernel method is preferred as the shell and kernel need to be at equilibrium. (the shell contains a higher moisture content because of the kernels higher oil content). The nuts are initially cracked, then passed through a mincer or grinder so that both shell and kernel are broken down to fine particles (3mm or less). This broken down mixture is put into a moisture meter for testing.
For the kernel only method, the kernels are broken down to a fine state (3 mm) and measured with a moisture meter. The maximum moisture level for shell and kernel is 9.5% and kernel only is 5.5% (requirement for Walnuts NZ Cooperative). It is important to note that walnuts are dried and tested after harvest in April and stored until processing. The moisture content may increase during the damper winter months in storage so it is recommended that nuts are dried below the maximum level to allow for slight increases in winter.
Many growers use a Wile55 moisture meter from FF Instrumentation 48 Hayton Rd Sockburn Christchurch. Cost is roughly $850. It is essential to calibrate your meter each year so that it is reading accurately. Alternatively, you can get another grower with a meter or send in a sample to Walnuts NZ Cooperative to measure the moisture levels of your walnuts.
The following factors affect walnut drying:
As a general guide, it takes 24 hours to dry walnuts using warmed air and 48 hours using cold air. Obviously, this will depend on what drying system you are using and climatic conditions.
There are two main types of drying systems.
Alan and Adrienne Robinson’s
During the field day we visited three properties all with different drying systems.
Firstly, at Alan and Adrienne’s we viewed their commercially made tower drier made by German company Feucht-Obsttechnik. The tower is about 4 metres tall using two steel bins just over 2 metres cubed. In the base of the tower, four 2.5kw electric heaters and a large fan causes warmed air to move up the tower. There is also a gas option from the manufacturer. Washed nuts are pre-dried using carpet driers then fed into the top of the tower using a conveyer belt. Each compartment can hold 350kg of walnuts but Alan adds 250kg each time which is the amount each small storage bin holds.
John and Wendy Hollings
The second property we visited was at John and Wendy Hollings. They had set up their whole drying operation in a large shipping container with two large doors opening out from one side. John and Wendy use a combination of blower and dehumidifiers to dry their walnuts.
A carpet dryer at the base was attached to 2 C section steel perlin profiles attached together to make a manifold duct that connected to 2 wooden drying bins. Two dehumidifiers produce 32 degrees of heat and can extract 90 litres of water from the walnuts. Dehumidifiers work more efficiently at higher temperatures and they create their own heat. This system can process 1000kg of walnuts in 2 days and has the capacity to process at least 6000kg over the whole harvest.
John calculated that is costs 11.6 cents a kilogram to dry their walnuts ($696 to dry 6 tonnes). The dehumidifiers cost $1950 each and the total cost including the container but without the dehumidifiers was $9000.
Tony and Ngaire Sigmund’s
The last property visited was to Tony and Ngaire Sigmund’s orchard and drying shed. Tony and Ngaire have built their own system of two drying chambers, built from insulated panels using a combination of carpet blowers and a dehumidifier. The dimensions of the drier units were determined by the size of the electrical fork lift and drying bins. A plastic curtain covers the entrance to both drying chambers for insulation.
Tony cut some of the insulation panels to size using a special blade ($50) fitted to a circular saw. The panels are joined together using angles, channels and rivets.
The insulated panels, channels, rivets and sealant were bought from Bondor for $2,150.00.
3 bins bought from Walnuts NZ cooperative for $873
Dehumidifier from Trademe for $750.
The carpet fans cost $430 each.
The electric stacker (forklift) from Trademe cost $2150.
Container cost $3500.
The power bill for the month of April was about $300 more than usual, so you could say the drying process cost $300 in electricity.
This year Tony will make two separate rooms rather than two interconnecting, which will mean he will need to purchase another dehumidifier.
He has to keep an eye on the temperature in the drying chamber, as the present set up easily reached the high 30’s, (from the dehumidifier) without any other form of heating.
The curtain needs to be lifted at times to stop the temperature going over 38 degrees.
The drying time varied depending on how long the nuts were pre-dried and amount of walnuts in the bins. It usually took about 48 hrs. After a day Tony would start taking readings which would be about 35° celsius and 65% humidity.
When the humidity got down to 45%, he would use the Wile 55 to measure moisture level of shell and walnut. He aims for a figure less than 8%, but would normally be about 7%.
Tony Sigmund Explains his system
Heather North recently found an original article about how to spray for blight, written by Clive Marsh and David David Manktelow.
It’s quite comprehensive and you can find it on the Blight Control page of www.walnuts.org.nz
You will have to register and login if you’re a first time user of the website.
In the previous two newsletters we’ve discussed “the promise of our industry”. What we are paid and the prices we can expect were covered in some detail in these articles.
The conclusions were;
It’s interesting to note that in this season (2020) some orchards have produced around 3000kg per hectare. This lifts our industry into a more viable zone. Our growers manual suggests that the range of production to expect is, low production 2367 kg per hectare and high production 4208 kg per hectare. Perhaps we just have to wait longer and manage better for our ship to come in.
Dave Malcolm ia preparing a comprehensive example budget which will be helpful in gaining more understanding of the viability of our businesses.
Anna Brenmuhl has kindly drawn our attention to an article in the online fresh produce industry magazine Fresh Plaza
The article describes the 2020 Californian walnut production as being 780,000 short tons, an increase of 19% over the previous year.
Under the headline “California walnut industry doubles down on US retail programs” there is information about how the walnut industry is mounting a promotional campaign to position walnuts as a top of mind snack. Their industry organisation has recently established a new section on it’s walnuts.org website dedicated to supporting retailers, dieticians and others who retail walnuts. This whole effort is being backed up by a multi million dollar advertising programme.
You can view the Fresh Plaza article here.
And the Californian Industry website promotion to retailers here
The consumption of walnuts is definitely increasing although reports from other sources indicate that lower prices are required to maintain the sales volumes.
Dave Malcolm and Heather North, 31 October 2020
There has been renewed activity within the research committee in the last few months. Heather North, the research committee chairperson, called a meeting recently, and we have been busy with various tasks old and new. These include a funding application to conduct research into walnut blight control, assessment of the data collected from the two ongoing walnut cultivar trials and looking at the results of the walnut mould analysis done by Plant Diagnostics at Templeton.
1. Research into the control of Walnut Blight using Trichoderma
In June this year, Johanna Steyaert from Lincoln Agritech Ltd approached the NZWIG committee offering to conduct research into the biological control of walnut blight using the naturally occurring Trichoderma fungus. Trichoderma has been used to control soil root diseases like Pythium, Fusarium Wilt, Rhizoctinia and Phytophthora. It is also effective at controlling Silver Leaf in stonefruit and ornamental plants. Trichoderma products are registered in New Zealand and are commercially available for certain applications. There are hundreds of different strains of Trichoderma and Lincoln Agritech are hopeful some of these strains may have the potential to suppress walnut blight.
With the help of Lincoln Agritech, the research committee submitted a funding application to AGMARDT in October for $20,000 to pay for the research which Lincoln Agritech would carry out. We hope to find out from AGMARDT on the 4th of November whether we have been successful.
Lincoln Agritech will use this funding to conduct laboratory based (in-vitro) trials to see if any of about 100 strains of Trichoderma have some control of walnut blight. This work is just the first screening step, and further trials would be needed to see if anything that was successful in the lab could also be successful in plant tissue and in real conditions in the orchard.
In future the research committee would like to design and seek funding for a larger blight control project, and any Trichoderma strains successful in the lab could be included. Currently we only have copper and Mancozeb products in our toolbox to fight walnut blight and solely relying on these products leaves us open to copper resistance and copper residues accumulating in the soils of our orchards. In addition to the Trichoderma strains, we are also interested in testing other biological control agents that have shown promise in California as well as an antibiotic called Kasugamycin.
2. Cultivar trials
You may recall that NZWIG has been evaluating walnut cultivars in two trials, planted respectively in 2005 and 2011, in which we have been collecting data including budburst dates, flowering dates, growth and yield. Also, with the harvested walnuts, we have assessed attributes such as size, seal, colour and incidence of disease. The research committee has been entering this data into spreadsheets and the next step will be to process and write up the information and summarise the attributes of each cultivar. Hopefully, we will have some information for you soon.
A good twenty years ago, some enthusiastic members of NZWIG, including Graeme Nicholas, set up the benchmarking project. The intention was for growers to measure the diameter of randomly selected trees in their orchards in winter and in January record the incidence of blight in their trees. Some yield data was also collected. This data was entered into a website called the Benchmarking Project. The intention was for growers to see how their trees measured up compared to the average. The research committee intend to resurrect this initiative and give access to the website. Watch this space for updates.
4. Mould research
We have been looking into the high incidence of moulds in walnuts from the 2019 harvest, with the help of Plant Diagnostics Ltd. We are glad to say that the 2020 crop does not have the high levels of moulds seen in 2019, but it would still be useful for us to gain a greater understanding of what the moulds were and what might have caused them to grow, with the aim of knowing how to minimise mould development in future. We are well through the project and aim to get a final report out to growers in the next few months. But, in the meantime, here is an update on progress on the four objectives (note that our last update came out in the April 2020 NZWIG newsletter).
Objective 1 (NZWIG): Literature survey on published information on walnut mould – COMPLETED. Plant Diagnostics looked into the scientific literature to find out what is already known about this problem, and has sent us a report, which will be very helpful for us.
Objective 2 (NZWIG): Lab analysis of nuts from 2019 harvest – COMPLETED. Report on mould types found has been received from Plant Diagnostics.
Objective 3 (NZWIG): Lab analysis of nuts during development on trees in the 2019/20 growing season – COMPLETED. We collected walnuts from the orchards of five growers in December 2019, January 2020, April 2020 and May 2020, and all samples have been analysed by Plant Diagnostics, with reports provided.
Objective 4 (Walnuts NZ Co-op): Survey of orchard management and environment factors – IN PROGRESS. We have carried out detailed surveys of 10 growers, including their canopy density, blight control programme, harvesting practices, and many other factors, and we aim to see if any of these factors appear to correlate with the level of moulds (high, medium or low) found in their 2019 crop.
Well, the website was built as a resource and it only just got going, and then was out of action for two months. Sorry for the inconvenience that the breakdown caused.
It’s now on a very fast and secure system with a local technical support person so let’s hope it serves us well. I think it will.
The site has lots of information and including a page of information from a recent field day about predicting blight, you can order a copy of the blight calculations spreadsheet there. Take a look.
Please give feedback and make suggestions, the website is there to support you.
If you haven’t this will be the last newsletter that we’ll send to you. Next time it will just be emailed to paid up members. Remember that subscriptions support Research, Promotion through walnutsplease.nz, Our growers website walnuts.org.nz, Field days, This newsletter. Representation to government organisations.
2020/21 NZWIG committee from left to right. Heather North, (Research Leader Co-opted), Hugh Stevenson, Kaylene Fenton, Dave Malcolm (Chair), Sonya Olykan (Secretary), John Hollings (Events), Nelson Hubber (Media),
Inset Above. Russel Hurst, Paul Visser, Anna Morris (Hon Treasurer)