2 From the editor
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Walnut Blogletter 29 – April 2017
This blogletter is a quick appeal for information from you lot. We have just had the absolutely worst season weather-wise that any of us imagined. A problem, yes. But it is also a once in a lifetime opportunity to learn about growing these walnut things. So please get on your computer and give us a quick description of how this season has treated you. If everyone does it we will learn answers to questions none of us ever thought of. So, if you are reading this, give us a quick note of how this season treated you. It only has to be a few lines.
To get you started here are a couple of email exchanges. Kate Carter has lost a big part of her crop, can you help her? Valda Muller in Otago was confronted with all her crop on the ground in one day, on a soggy boggy ground. Is this the weak link in machine harvesting? [Read more…]
Walnut Blogletter 28 – March 2017
Covered in this blogletter is our continuing battle with Phytophthora, and the latest results in our search for better walnut varieties. Plus I have thrown in a few notes on random walnut topics spotted on the internet.
A follow up on our stumping experiment…
In the May 2012 blogletter I described an experiment of ‘stumping’ some 4 year old trees that had been knocked over by a slip. That winter I cut off the tree as close to the stump as I could get and a year later had a profuse coppice of shoots about a metre high. Each summer, to avoid excessive bleeding, I reduced the number of shoots, till I finally got it back to one shoot last year; 4 years after the initial stumping. I think it was a success in terms of tree form, and the growth is not far behind the neighbouring row of trees that was not touched by the slip; well worth doing. [Read more…]
2 From the editor
by Ben Gaia, West Coast TCA, dialatree.co.nz
Cryptomeria japonica, the Japanese Cedar, sometimes called Japanese Redwood by foresters, should be a widely planted timber tree for New Zealand. For thirty years I have been growing and promoting timber trees, especially alternative timber species to wean off our reliance on pines, which although healthy and fast growing, tend to blow down on a large scale. Pinus timber is only allowed in buildings with highly poisonous timber treatment chemicals. Cedar doesn’t require poisoning to be durable and insect resistant. Large plantations of stable, durable Totara would be my first choice to replace pines in this country, but my second choice, and one with quicker economic potential, is the Japanese Cedar.
Known in Japan as Sugi ( 杉 ) it is highly revered as its timber is light, durable, scented, beautiful and strong. Vast stands cover the Japanese mountainsides around all the main inhabited areas. It is planted around temples for its perfection of form and ornamental quality, with examples up to 1000 years old. Huge trunks of these cedars are carefully tended over up to 400 year harvest rotations for temple pillars and gateways. Now that’s forward planning! I have seen brand new pillars bigger than you can get your arms around in Narita City at the restored Narita-san Temple there. Their golden colour and straight perfect form should inspire us to grow more of them here. Especially as here on the West Coast they can grow to a massive size in only 70 years. With high rainfall, they even keep up with Pinus radiata on a well drained site if pruned and fed properly, yielding good sized six metre clearwood in under thirty years. Strong root systems resist wind throw. I recently had to mill some as they were too close to a power line; we got good bench top sized 4 metre long flitches out of two sixteen year old trees. This is fast growing by Kiwi standards: astronomically fast growing by northern hemisphere standards.
We have been growing good Sugi on the Coast since early experimental plantings from the 1930s in Mahinapua State Forest. My old friend Willie McPhedran milled some and said they were long, straight, and a beautiful reddish orange colour at 70 years old. Many people will have seen them growing along state highway 6 on the south side of the Reefton Saddle. They have the shape and colour of our own native forests, resembling large olive-coloured matai or silver pines to look at, but growing five times faster. I cannot understand why we don’t have huge state forests of high quality Sugi, Totara and Redwood, which would provide jobs, carbon sinks, and high value timber both for export and for building all those state houses we need. Come on Kiwis, it’s never too late to plant trees, and Pinus radiata is a very poor cousin of Cedar. Ask any builder. Carpenters ooh and aah whenever decent wood like Cedar or Douglas Fir arrives on a job. They run their hands over it and inhale its spicy scent in admiration. It doesn’t need poison, thus cleaning up the environment and working conditions for sawmillers and builders alike. It is even fire retardant which makes it even safer in houses or low rise wooden office blocks.
This is why they are my favourite timber tree. We should be growing millions of Sugi – Japanese Cedars to assist and enrich our country in so many ways. If you are considering a woodlot anywhere with good rainfall, consider planting half of it, or more, in Cryptomeria japonica.
Last July I introduced the blogletter with this paragraph.
With the huge increase in walnut plantings around the world, especially in China, we need to focus on what advantages we can exploit for walnuts grown in New Zealand. Massive planting has also been happening in countries around the Mediterranean as well as non-traditional places like Australia and Chile. Even in USA the big increase in walnut area is meeting headwinds now their exports to China are finding resistance. We need, and will need even more in the future, to exploit our competitive advantages. In this regard I view any differences in approach, a strength.
So whatever you are doing with your walnuts, let us hear about it, so we can all learn.
To which Valda Muller replied;…
We sell all of our walnuts direct to customer – either farmers market or mail order. The majority would be in halves and pieces. We tend to be sold out really quickly so at this stage I feel that we still have space to grow our market
Valda [Read more…]
Very sad news. Les Gruebner, a long time Bay of Plenty Tree Crops member, died quite unexpectedly on Monday night. No other details are available at the moment. Les was a major force behind NZTCA getting a website, and was also very encouraging to me producing this blogletter. He will be sadly missed.
Thanks for the recent newsletter. I wonder if you can help me with something I think I read somewhere.
I seem to recall reading in a newsletter somewhere an advert from an organisation that were buying up walnut shells for use in, among other things, the cosmetic industry.
I’m reasonably confident I read it in a treecropper related document but now can’t find it anywhere. Was it in one of the walnut newsletters? Or do you perhaps know of someone that buys the shells. I’m up to about 40 litres so far and would like to see them do to some use.
Thanks in anticipation.
I cannot think of any NZ demand for walnut shells that I have seen advertised. Can anyone else help Patrick?
We use ours to heat the house. Crain Walnut Shelling, Inc used to have a full page on their website of uses for walnut shell, but I cannot see that page on there anymore.
Thanks again for your most interesting and helpful blog. It is so kind of you to go to the trouble of circulating yours, and others experiences, and contributing information..
Last season with our 20 odd mixed variety (Rex, Meyric, Franquette, Wilsons Wonder, Shannon, plus a few seedlings), and aged ( 2-30 years) trees was a medium yield year , opposed to last years bumper crop. Early and late nuts were black inside. The rest very good. That’s usual, I believe.
I have started to apply Boron in the last couple of years and have noticed less ‘stag-heads”.
I was going to send you the write-up of a fielday here by the local (BOP) Tree Crops Association, but it hasn’t appeared in their newsletter yet, so perhaps I am a bit premature. So, I have attached the write-up for the visit by the BOP Farm Forestry Assn. back in November. I cannot resist the temptation to edit it a bit. My changes in brackets.
BOP Farm Forestry Friday 13 November: Nelson-Parker property, Wainui.
On entering the property we drove past the lovely flowering Rhododendrons and parked under the loquat tree (yummy too).
Nick gained his interest in forestry via his grandmother and a walnut tree she was offered two thousand pound for (which was equal to two years’ salary back then), so Nick thought, “I’m going to do that – grow walnut trees for timber.” He then went hmm I need to consider returns and cash flow impacts etc, and realised the importance of other species as well. He worked with Radiata pine for 17 years.
They have been on this 26.7ha property for 38 years, and now have some 5ha planted in [wal]nuts. They struggled to get walnut trees established so they joined the Tree Crop Association and Farm Forestry Association and set up a nursery to fund his addiction to trees. Their soils are high in Potash. Nicks quote of the year “our soils are nutrient free”, just require a lot of micro nutrients (trace elements). Found boron is required. Uses leaf and soil analysis, but still believes visual is best. The trees tell you the truth.
- Nut quality important
- Hard to graft (10-40% if lucky)
- Started with seedlings, but is now convinced grafted stock do better.
- Heavy loam wet soils lead to phytophthora
- Prune regularly- like annually
- Still evaluating varieties
- For the nuts none are really good- slowly getting there via selection.
- Deer like Black Walnut not [European walnuts e.g.]Lara
Use[have tried] pheromone traps for codling moths. Puriri moth is a nuisance in the walnut [tree] itself, but not a major concern. Have both a bacterial and a fungal blight affect the trees.
- Aim for straight stems rather than bigger diameter stems in early years- albeit diameter is important also.
- Lots different characteristic needed in your nut. Range meat to shell ratio in varieties range 35% with new American one at 50% and even known to achieve 62%.
- Varieties Nick had include Tulare, Lara, Diana, Shannon, 15A/1, Awakeri. Harvest nuts April/May.
- From 35 year old seedling trees get approximately 1T/ha, whilst the grafted blocks [Roadside 12] produce 2T/ha.
- The nuts sell readily in the markets.
- SR[plant]- tight early to hold form. A 1986 planted stand was at 400stems/ha now and these would be thinned to 80/100stems/ha in time. A 38 year old stand was at 160 stems/ha and just getting crown closure.
- If planning to mill in future do [logging] cuts in late autumn (May/June) so don’t get checking and splitting [in the log]. Form prune in November, take out biggest branches in crown. Nick will do a double cut to avoid strip tears[down the trunk].
- Jaap suggest cutting at the stump of non-straight trees and letting coppice which would send up a nice straight leader over the first few years. Nick mentioned they did do this in UK.
- What/how select wood/nut. Lot discussion around these topics.
- We also inspected some Chinese cork oak and another proper cork oak (better [cork] timber).
- Nick has also planted male and female of an endangered species [Araucaria angustifolia]
- Paul Silcock from NZ Forestry Ltd spoke of their black walnut trials in Whangamomona (The forgotten Highway). Some were in stands of 950 stems/ha being half alders as a nurse crop.
While we are talking about walnut trees for timber, here is a clip I found in the VII International Walnut Symposium as tree species suitable for forestry plantations
..walnut (J. regia) to be exploited as tree species suitable for forestry plantations, recently had a lot of impulses from the Italian Agricultural Ministry and, specifically, with the promotion of the Riselvitalia project. In the framework of the above mentioned project the “Istituto Sperimentale per la Selvicoltura” of Arezzo has developed a research aimed at the exploitation of some selections of a J. nigra population, identified in North Italy and characterized by a spontaneous inter-specific crossing ability with J. regia. The Persian walnut grows slowly with respect to J. nigra that, on the other hand, produces lower quality wood comparing to J. regia.
The Italians use a lot of European walnut logs, so I found it interesting that they prefer the wood quality to black walnut.
What the heck. Here is the Tree Crops fielday too. They have said I can put it in the blogletter anyway.
Tree Crops Field Day report May 2016 Nick and Pauline Nelson Parker
The beauty of Field trips is that our hosts invariably share their hard won experience and knowledge in entertaining ways. In this case the anecdotes were recounted with a dry sense of humour. For example, when initially seeking finance for this property, the banks weren’t interested in lending for a walnut growing enterprise. Apparently the bank manager asked “Is there anything else you want to grow?” When Nick said he was going to put in some kiwifruit, the bank manager said “Kiwifruit! Why didn’t you say so! How much do you want?” In fact Nick says that decades later he tangled with Arguta kiwifruit he planted as part of the nursery operation “they terrified me, you can’t control them, they grow so vigorously”.
The Nelson Parkers have been members of the Tree Crops Association members since 1976. They bought this property to grow walnuts, for timber as well as nuts, and now have about 5 hectares of walnuts planted. Initially they set up a nursery to fund the venture, which they closed around 2001. They have done this,[after closing the nursery,] with no staff, no Wwoofers, “ïf we can’t do it ourselves, we don’t do it.” The walnuts from this property are sold at Ohope and Tauranga Farmer’s Markets, where there is plenty of demand. There could be useful timber on some of the older trees, now nearly 40 years old. However the timber only gets better and could be harvested at any stage over the next couple of hundred years!
Within minutes of beginning his talk, this walnut expert was telling us that :” it doesn’t matter which variety you plant, none of them are any good.” That left me wondering about the tree I bought from Nick at a Tree Crops tree sale a few years back! The advice that followed was more useful; “the main thing is to pick up the nuts within 1-2 days of them falling, and wash and dry them within 4 days.” But then another blow “providing you can get them out of the shell”.
The first walnuts planted on the property were grown from nuts purchased at a Tauranga supermarket. Lines were cut through the scrub and walnuts planted at 1984 stems per hectare as for radiata pine. After culling they are down to 160 stems per hectare. With seedling trees they are planted at 700 stems per hectare. Some, such as grafted “Roadside 12 ” and “Rex”, were planted in blocks at 400/ha and still thinned out. Trees with inferior quality nuts are marked with an X.
Some of the trees here are on quite steep slopes. Bird netting is placed on the ground every year to help the nuts roll down the slope where they can be more easily collected by roller or by hand. Nut rollers can also be used for collecting acorns, feijoas and even golf balls.
Washing is only required if the nuts are muddy or dirty. Here they are washed on old wire wove bed bases on frames.. The greenhouse is ideal for washing, as there is good light in order to identify rejects to cull. These can be hard to spot in the shade under the trees. The nuts are bagged straight away.
Drying involves forcing air through a column of nuts, within a sealed box containing a dehumidifier, for a couple of days. The nuts will go off if the temperature gets too high, > 44degrees C, so the box is painted black to radiate heat. If they need to be stored till there is room in the driers, they can be left on racks in the sun with good air circulation. There is a finishing room with dehumidifier where the sacks are kept till repeated weighings show no further loss of moisture/weight. All this because quick drying is the key to a good tasting walnut. Bill Rae described seeing walnuts opening and developing roots within 4 days of falling.
Storage moths can be a problem so the aim is to either store the nuts in the deep freeze or to get the nuts off the property as fast as possible. [Someone said] Bay leaves can be useful to deter these moths, place a few leaves or a branch wherever dry food is stored e.g. in the flour bin or in the pantry.
We were told by Nick that “no varieties are any good, it’s just that some are worse than others.”
Crackout rate is a key indicator. It refers to the ratio of edible nut or ‘meat’ to total nut weight with shell. Typical crackout rates for different cultivars include: Wilson Wonder 35%, Rex 39%, Franquette 50% and Roadside 12” 39% This variety met with some approval, yielding about 2 tonnes per hectare.
This is another critical indicator. 1 tonne per hectare is common but not enough to be economically viable. In California and China crops of 6 tonnes/ha are being achieved. On that scale, big investments are being made in machinery to shake, sweep and dehusk the crop.
Three newly imported varieties are being trialled at the Nelson Parker’s orchard. The best so far is a French cultivar called Lara with a crackout rate of 50% [43% actually]. There is a cultivar from Awakeri that hasn’t been released yet that promises a 62% crackout rate.
The Nelson Parkers still plant quite a lot of seedlings, which produce a very variable tonnage per hectare compared to the grafted trees. Planting a range of varieties, whether of seedlings or grafted, is some protection against planting all of one variety and finding later that it was an unsuitable choice. As with many tree crops, the consequences can show up much later . . . On a grafted walnut tree nuts might start to be produced in year 1-2 after planting, although often 3-4 years. The fastest fruiting off a seedling tree is 18 months, but typically takes from 10 – 16 years.
The grafts are done on 2 year old rootstocks. Black walnut is the preferred rootstock as it offers some resistance to phytophthora. After 30 years experience grafting Nick has gone from a 20% success rate to 50%, his grafting mentor claims an 80% success rate. With other grafts Nick will typically use a whip graft, but he uses a “bit of a tongue” on the walnuts to hold it together.
PLANT HEALTH, PESTS, DISEASES AND WEEDS
Nutrients according to Nick, “walnuts need everything, and lots of it”. Nick described the soils on site as being “nutrient free. Except for too much potassium.” In Nick’s experience, the results of soil and foliage tests e.g. for boron and potassium, don’t always match with observations of the trees themselves.
Codling moth can get into the nut in the early stage, October and November, and those nuts tend to fall off the tree. Later in the season, the juvenile stages of codling moth enter the nut through the base of the nut. Various members shared their favourite strategies for reducing codling moth including: solar lights placed in a bottle of water, treacle and vinegar mixtures in containers that exclude bees and bumblebees, corrugated cardboard around the trunks to harbour migrating larvae which are then removed, chooks scratching in the understory, encouraging tuis bellbirds and other insectivorous birds and UV light fly killers mounted outside from November to January. In California the native bats are encouraged by placing bat houses in the walnut orchards. Some varieties are affected differently depending on timing e.g.- Wilson’s Wonder is an early cropper, Franquette is later. For commercial producers it seems none of these remedies are completely effective.
Blight outbreaks depend on the season. Wet weather around November and December is not good. Pruning the trees up, i.e. removing lower branches, which is done anyway for timber production, may help by improving air circulation and reducing splash from the ground. Copper is used in some parts of the world but application e.g. by helicopter, is not feasible on this scale.
Someone asked why their own tree produced nuts with a perfectly formed shell, but a shriveled, pea sized nutlet. The long process of nut formation was explained. In mid December the walnut starts making the shell, by Christmas the shell is formed, after that the nut is filled with kernel. Any interruptions in the development process , e.g. water stress as in Californian droughts, can result in no kernel or no shell. Fortunately droughts are not common in Nukuhou. In fact the Bay of Plenty is arguably too wet for commercial walnut growing on a large scale because of diseases such as blight.
Northern California is a big walnut producing area. It’s not only the humidity that is different, it is also very flat, which makes flood irrigation possible, and harvesting etc very much easier.
Shade and auxins produced by walnut tree roots reduce weeds under the canopy. Herbicide is also used.
Walnuts, like pecans and hazelnuts, are wind pollinated. While walnuts are generally “not hard to pollinate” the best crops form when there is a massive cloud of pollen.
Male flowers, held on long drooping catkins, can be scarce. However even two male flowers on a whole tree may be enough to get some nuts. One disadvantage of higher rainfall is that the male flowers can rot on the tree.
When the Nelson Parkers arrived, the site was a ‘block of scrub’. Countless trees have been planted over the decades. Many have provided lessons and/or stories: pine nuts which dropped cones through the clearlight panels in the barn roof; cork oaks, “life’s too short, you have to concentrate on one thing”; gleditseas “make great timber for turning, cut out the males to reduce seedlings”; Acer saccharum the real sugar maple as opposed to Acer saccharinum; the Meyer lemon planted well away from the other citrus near the house to prevent pips forming; male and female carobs, which have fruited; chestnuts, prickly burrs watch your feet “Disk 2 is a good variety”; fast growing paulownias; figs -Adriatic nice bitter taste, Brunswick good general fig with a long season and Brown Turkey which is too sweet for Nick but his granddaughter loves it; gevuinas which have useful foliage for floristry but the nuts “taste like dirt”; crabapples, bananas, and shag bark hickory to name a few.
All the best
nick nelson parker
Reproductions. If you would like to reproduce any of nick’s blogletters, you must include the source of your quote and the following email address email@example.com
The May Walnut Industry Group (WIG) newsletter raised some issues in my mind.
It seems that we were not the only people to have a challenging walnut harvest with prolonged autumn rains. This report was in April this year. Intense rainfall has had a major impact on Chile’s walnut production, in particular the late season Chandler variety, says the grower and exporter association Chilenut. You can see the full article here.
The report went on to detail how the rain not only caused significant loss of production, but quality downgrade for part of the harvested crop too. They also said that further rain was forecast which was going to cause problems in harvesting the last of the crop. So, reading between the lines it appears the rain must have disrupted mechanized harvesting, and meant nuts that were collected were left out in the rain too long.
Nelson Hubber, chairman of Walnut Industry Group (WIG) also said, ” Like many in Canterbury this year Meyric produced the best and biggest crop at our place. Rex let us down with a very small crop due to a November frost. Only a fraction of the amount of last year.
Up in the Bay of Plenty production was good, but Rex only had a light crop even though we did not have the November frost. All these observations highlight a classic growers dilemma. How many varieties do I grow?
- There are pluses and minuses.
- A range of varieties with a spread of pollination and harvest times gives longer to collect the crop, with less pressure on facilities and machinery, and of course, insurance against those unusual weather events.
- But the flip side is that only having limited selections enables the grower to fine tune machinery to nut sizes and shapes.
- In theory one would hope that the main variety planted is the most productive, and any others added to the mix will lower average yield and/or quality.
The problem with all of this is that a walnut tree is productive for decades, cannot be topworked in New Zealand, and new varieties are coming on the scene all the time. How did you decide what varieties to grow at your place?
California’s 2015 walnut acreage is estimated at 365,000 acres, up 12 percent from 2013. Of the total acreage, 300,000 were bearing and 65,000 were non-bearing.
Of the walnut acreage reported, Chandler continues as the leading1 variety with 104,450 bearing acres, followed by Hartley with 33,002 bearing acres. Chandler also accounted for 67 percent of the non-bearing acreage.
Chandler was released in 1979. That was quite a while ago. Hartley has been around from 1915.
Combined sales of walnut trees to California growers were 18,021 acres for the 2015 crop year. The Chandler variety accounted for the largest percentage of new plantings at 75.8 percent. The Tulare variety came in second at 14.0 percent, followed by the Howard variety at 6.0 percent.
Tulare and Howard were also released in 1979. So does the release of Ivanhoe in 2010, and now the release of Durham this year cause a change in varieties planted?
Here in New Zealand, WIG imported Tulare and Howard, but not Chandler. That was probably a wise move as our climate is quite different. The third variety that WIG imported was Lara, a new French variety, released in the 1980’s. Trials on our place show Lara cropping better than Tulare. But is it more productive than Shannon (1335) which was the best producer at the Masterton trial?
In the 1980’s California produced 80% of the world walnut crop. Production had gone up from about 2 tonnes per hectare (t/ha) in 1970 to 3.5 t/ha in 1979. The area in bearing had only increased by 5% in that time, but management had become more professional, with better machinery and varieties. The most promising selection, Serr, released in 1968, turned out to be a fizzer with very variable cropping caused by what turned out to be Pistillate Flower Abscission. (The flowers don’t set.) Consequently growers were very cautious with new varieties, sticking to ones that they knew; Ashley, Payne, Vina, Hartley and Franquette.
But in 1983, that all changed when California suffered a season like the Chileans have just had. All their beloved ‘proven’ varieties except Hartley bombed out. Only Chandler and Howard, which had just been released, produced marketable kernel; and everybody wanted them. And now they are averaging a yield of nearly 5 t/ha.
So what has this got to do with us growing walnuts in New Zealand?
Christchurch growers have settled on Meyric and Rex, and have not planted the heavier bearing Shannon extensively. In spite of Shannon having beautiful nuts, Rex has been planted because of its kernel quality. It is going to take a much better variety for people to shift. Lara might be a contender. It does have the kernel quality.
North Island growers, with a wetter climate, are comfortable with Wilson Wonder. Some are starting to plant Shannon and Roadside 12. Will Lara be an option?
How did you decide on what walnut trees to plant? Let us have your stories. It will help those who are still planting, or about to plant. For my part, I am still putting in trees, and it is quite difficult to decide what to propagate. This year I have planted Shannon, Roadside 12, and interesting seedlings from the breeding programme.
Incompletely formed walnut shells – Cause?
Trudi and Basil Meyer [Located in Darfield, Canterbury] sent me this email;
I thought I [would] send you some photos of some of our walnut shells. They seem not to have totally formed and look disfigured.
It predominantly happens to Tehama and Meyrik Walnuts. And we had quite a lot of it this year. We are looking for some ideas how to prevent it in the future.
Let’s start with the basics; how a walnut develops on the tree. My understanding is that we start with the flower in October/November which is not much more than an ovum inside a miniature husk. As the nutlet develops it is mostly growth of the husk with a rudimentary beginnings of the shell inside. The shell is nearly full size mid December, and only then starts to harden up, (lignify). Once the shell is fully developed, the kernel inside starts to develop and fill out.
From your photos, it looks as though something happened to your trees when the shell was forming that meant there were inadequate recourses for the tree to look after itself and form shells properly. I only know of two limitations to shell development in NZ; nutrient deficiency (It typically happens with boron for Franquette at our place.) or drought. Did you have a bad drought at Christmas time?
I googled it and found a Chinese article that looked at the problem and reported that it was correlated to variety and also to sunlight intensity. Presumably the nuts were cooking on the tree, which can be a problem in California too.
You also might like to look at this article from the University of California. ‘Drought Strategies for California Walnut Production‘
Are we getting close? Maybe we can work this out together? Did any other bloggers suffer similar shell deformation?
While we are on the subject of how walnuts form on the tree; an article I found on the net. (My bold highlighting);…
PRELIMINARY ELEMENTS OF REFLECTION ON THE POSSIBLE PRESENCE OF VITREOUS OR TRANSLUCENT WALNUT KERNELS
In France, walnut distributors are often disturbed by the presence of a proportion of « vitreous » walnut kernels which appear vitreous after drying and at the beginning of the breaking operation. The Creysse Experimental Station has undertaken a study in 1995 to try to understand this phenomena. Observations were targeted at the formation of the nut (type of soil / fertiliser / irrigation), before- and after-harvest parameters (date of harvest / maturity / period spent on ground / time before drying / drying conditions). The analyses, which were carried out on dry nuts (November) and after six months of conservation, were based on the general aspect of the kernels (calibre, colour, etc.), as well as biochemical analyses on the walnut kernels. The early results show a relation to : – Irrigation : a significant difference between shortened or prolonged irrigation on the percentage of glassy walnut kernels following harvest and conservation, – Harvest date : the walnuts harvested by vibration are more vitreous than those which fell naturally; there is a higher percentage of vitreous walnut kernels in those harvested in the husk, – Period spent on the ground : unlike other parameters (particularly colour), the percentage of vitreous walnut kernels tends to decrease with the increase of time spent on the ground. Hypothetically, it can be suggested that this phenomena is either connected to a change in the water content of nuts, with this content decreasing over time as the nut dries, or that the percentage of vitreous kernels is lower when the walnut kernels are coloured, or that these two parameters coincide. – Drying conditions: Walnuts dried at a lower temperature and at for a longer time have a higher « vitreous rate ». « Vitreous walnuts » do not seem to present any anomalies at the level of general biochemical parameters.
I thought this was a cautionary experiment at this early stage of our industry’s development. I am always getting complaints from my customers about the walnuts from the States that are translucent,(vitreous) in appearance. We have never noticed more than the very occasional translucent kernel, presumably because our primitive operation allows the nuts to mature and drop naturally, whereupon we pick them up as quick as we can. But what would happen if we shook them from the trees with tree shakers? Do any of you shake your trees? And what is your experience with translucent kernels? The experiment also hinted at some connection with irrigation practice. What is the experience of those of you who irrigate? The connection with irrigation implies to me that translucence can also occur when there is inadequate moisture to properly develop the kernel late in the growing season, even if the shell has formed properly.
If you google ‘translucent walnuts’ you come across Cracker-of-a-Nut website cautioning suppliers about drying their nuts properly. They describe rubbery incompletely dried kernel as translucent. But I would see that as quite different from the greasy kernels that have been shaken from the tree before they have formed properly. Would you make this distinction?
Trudi is one of the few who have gone on the walnut blog on Facebook. Maybe it is time to revisit this. If I lost control of the Walnut Action Group blogging and it became Facebook based, that would suit me just fine! Just log onto Facebook and search for NZTCA Walnut Action Group.
All the best
nick nelson parker
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July Field Day
2016 Annual Tree Sale Day
Venue: A & P Showgrounds, Katikati
On: Saturday July 16, 10am – 12.30pm
Good variety of fruit and nut trees at reasonable prices plus other plant stalls from Katikati and other areas.
We aim to have early, mid season and late varieties of major fruit groups so gardeners have fruit all year round.
We will be having our usual club stall so start preparing any plants you may want to donate to this. Do remember that any of you who wish to put up your own stall we encourage you to do so. Just let us know so there’s enough space – please contact Elizabeth Rae 07 549 2795. Same as other stall holders fees are 10% of takings. If you think of any other garden based firm who might like to come please let the committee know so the applicant can be considered and approached if suitable.