The Walnut Blogletters is a series of newsletters by walnut expert Nick Nelson Parker.
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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…] about Walnut Blogletter 29 – April 2017
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…] about Walnut Blogletter 28 – March 2017
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
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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Walnut Blogletter 21 – Introduction
A few random thoughts coming your way, mostly in response to emails.
If you hear some walnut news or observe something interesting in your orchard, let us hear about it. We can all learn.
If you have made or are selling walnut equipment that would be interesting too.
All the best as you count down to the next walnut season.
Enjoy: Blogletter 21, click to open in PDF format…
Not having put out a blogletter 18 for a while has been eating at my conscience, so with another season underway, I thought I would try and get the conversations going again. This will be a short letter, with the aim of eliciting your comments and stories, which is what most participants value.
I find every season is a one-off, and leaves you quite unprepared for the next one. Early spring for us was beautifully dry and that showed in very low incidence of brown apical necrosis (BAN) and bacterial blight in spite of not spraying (reasons later)…
When early summer turned to custard with persistent drizzle, bacterial blight really set in; black nuts everywhere. Some varieties were hit particularly hard. Serr and Meyric were among the worst. Fortunately normal summer weather resumed and gave us a half-crop.
How has this season gone for you? Think about it; your experience could help us all.
How different varieties respond to the climate and to your region is collective knowledge to build on. Did some varieties have a year off, or maybe conversely, crop better than usual?
As the harvesting season unfolded with a near perfect procession of storms to bring the nuts down and dry weather to pick them up, further light was shed on the earlier growing season. Normally a nut infected with blight will be a write-off. This year the blighted nuts were largely O.K. It was a pain getting them out of their husks, but the kernels inside were beautiful; white and very tasty. Hardly any nuts were infected with BAN. Those that were, had rotten kernels as usual. So the interesting thing for me to observe was the different effects of these two diseases, and that will be a consideration in any future disease control.
It looks to me that BAN can only do serious damage to the really small nutlets; at the stage you would normally spray at the “praying hands” stage. Bacterial blight seems to be able to infect nuts throughout the growing season, but once the shell has formed, for us in Bay of Plenty at the end of December, the kernel is safe. These are the observations of a simple grower of course and are completely unscientific.
One further development this season has me wary. In one block, about one nut per bucketful had an insect exit hole. Would this be codlin moth? We have never had insect damage before, and it is strange that it coincides with our free range chickens, or should I say feral chooks, being wiped out by some stray hunting doges. I hear that a parasite/predator for codlin moth has been released in the Hawkes Bay apple orchards. Does anyone know how to get hold of it?
Walnut with exit hole. This often occurred on the suture line, but not always.
The decision not to spray was based on economics rather than biology. We sprayed the previous season, the weather was perfect, and the crop double this year’s, and still the return did not cover the cost of spraying, There are two reasons for this. Firstly our spraying costs are high. We have big trees on steep land, so have to use a helicopter. But the main reason is that our yields are too low. That is a result of using unselected seedlings in our oldest block. But most other older grafted varieties would not be much better, with the possible exceptions of Shannon or Roadside 12.
We can all learn from stories of dealing with different seasons in different locations. Did your preparations work? We added a dryer. Mark II of our dehumidifier based design, and now wonder how we managed without it. Did you try new systems or new machinery? If you dry your own nuts, can we focus on that in the next blogletter, with pictures and descriptions of how your machine works?
Quite often I get asked, “What walnut variety should I plant?”, and my answer usually is, “It depends.” Not very helpful, I know, so perhaps we can collectively explore this subject in greater detail.
NZ Tree Crops Assn has published results from two different trails, (discussed in detail in the Tree Cropper) one comparing blight in the Waikato, and one looking at yields in the Manawatu. Since the 1970’s, focus for the industry has changed from being solely interested in nut quality, to consideration of different aspects of nut quality, yield in different locations, consistency of cropping, disease resistance, time taken to cropping, seasonal leafing-out-time and even the effect of rootstocks. One initial concern was pollination, but this has turned out not to be a problem with walnuts here, except that seedlings take ages to produce any male catkins.
WIG are doing two series of comparative variety trials. It will be several years before any results emerge from these, but they are important because new varieties are being tested, including 3 U.S. selections imported from Australia. There are two NZ Tree Crops Assn trials on my place as well, looking at new varieties, and also having another look at some of the older varieties like Wilson Wonder.
So, of the currently available cultivars, what do we know? The strong favourite at the moment is Vern Harrison’s selection, Shannon.
Shannon was the most blight resistant tree in the Waikato blight trial. It was the heaviest, and most consistent cropper in the Manawatu trial. From what I hear it is also performing well throughout New Zealand.
Rex is the most widely planted variety. As a young tree it was the heaviest cropper in the Manawatu trial, but as the trees developed it was overhauled by Shannon. Perhaps this early cropping ability has been an important reason for convincing growers to plant it.
Manawatu variety trial results in 2013
|Variety||Total kg nuts/tree
yr 2008 to 2013
|Between tree R2||On Off Ratio|
The correlation coefficient (R2) of 0.84 for Shannon shows there was not much variation in cropping between individual trees in the trial. The OnOff ratio is a measure of the crop in an off year compared with the on years either side, i.e. a measure of biennial bearing. The higher the value, the better.
Shannon scores highly on both measures, as do Roadside 6 and 12. Dublin’s Glory behaves quite consistently one tree against the next, but are badly affected by biennial bearing. Meyric has a big difference between good and bad trees and terrible biennial bearing. Rex is quite consistent one season to the next, but cropping for individual trees are all over the place.
Nut yield is an important consideration. Nut quality is another factor.
|* new varieties in the WIG trials.|
Those are the numbers, but grower perception, mine included, can be quite different. So I repeat these comments from a previous blogletter.
Comments on individual cultivars by Jeffrey Feint in 2011
– Meyric are by far our best nut but the shells we produce in Wanaka seem incredibly fragile, and I have almost reached the stage of abandoning any sort of machine harvesting because I estimate we lose up to 20 % of nuts due to breakage of the shells even when something as light as a quad bike with wide wheels runs over them.
– Rex is not my favourite nut and frequently very small and difficult to handle falling through the spaces in our walnut washer, but was our first nut to start falling in early April
– Franquette are often large and thick shelled, sometimes they look externally to be a good nut but on cracking them they have poorly developed kernels, especially if the nut looks “ moist” externally. They are also incredibly hard to dry and several years ago I lost several hundred kgs when although I thought that they were well dried they developed a grey mould both inside and outside the shell whilst in onion bags!
I think that one also has to realize that one does not have a single run with a harvester or whatever one uses for harvesting, but that during a harvest one has to make several runs with the harvester, even if a tree shaker is used.
Our nut yields seem to have plateaued at a little over 3 tonnes with our 450 or so trees being between 13 – 17 years old, but I calculate that we should be closer to 10 tonnes or more – I am really at some loss to work out how to increase this yield and would welcome help.
– Stan (Blenheim 300) – a good nut which are easier to process because they are round and do not jam so easily in equipment. Quite a nice nut to taste, relatively early fruiting.
– Wild Nuts – we originally planted about 80 wild trees which I regret because some produce quite good nuts but others are small and do not taste very good.
A typical Franquette nut with poorly formed shell and rotten kernel that I am putting down to Boron deficiency. The shell is ultra thin along the pale lines.
Franquette is a very late leafing variety, and is planted in the South to avoid out of season frosts. I have also found Franquette to be particularly prone to Boron deficiency, so much so that they never cropped at all for years. The comments Jeffrey makes about drying them applies to all the larger nuts. Drying takes much longer and needs to be very thorough. On the other hand we have found that a big nut is much quicker and easier to pick up.
The closer you get to Auckland, the more likely you are to try and grow a big table nut. We have bred Roadside 6 and 12 as an alternative to Wilson Wonder. In the Bay of Plenty we find Roadside 12 out performs Wilson Wonder most seasons, but it has a problem with some kernels not being filled out. Roadside 6 seems to avoid that problem, but the nut quality is not quite as good. Every variety has its good and bad points!
The interaction of variety with site is critical. I have yet to find a way to make Meyric crop here, but we have no problem with out of season frost on any variety. On the other hand a good hard winter seems to increase our crops through initiation of flowering. It is this site interaction that I am hoping will trigger your feedback. Send me your stories about what varieties you like, and where things have turned out different from expected.
I sent a draft of this blogletter to Jeffrey Feint, and got this reply….
Great to hear from you again . We are in the middle of our harvest which is far too late since the leaves have well and truly fallen and for the last 4 days we have had almost constant heavy rain , which has effectively stopped any nut harvesting . On top of that we have had machinery breakdowns – the main motor to our washer , and the hydraulics on our harvester . All in all this tends to make it “ a harvest from hell “ , although after 2 years of very low yields we have a good crop which should come in around 5 tons.
Most of the comments I made in an earlier blog are still pertinent to me – our Meyrics remain our best nut but they are so fragile , and after drying and whilst bagging the shells literally seem to fall apart ,and I think that we must lose 20 % or more in fractured shells which are discarded .It has been pointed out to me that if we hand rolled them all then we wouldn’t have all these breakages but hand rolling over a ton takes quite a bit of time and personnel which we don’t really have . Valda Muller points out to me that Meyrics are also very hard to crack mechanically since the bits stick inside the shells , but I don’t really have any other nuts in comparison .
In our Central Otago environment Rex seem to be frequently hit by late frosts and this could be due to the fact that they don’t have big leaves like the Meyrics to protect the buds . A problem which I have always found troubling is that we struggle with very small nuts on Rex’s and Blenheims – to make a double entendre no man likes to be told that he has “ small nuts “ , but I have tried extra watering , fertiliser, ‘poisoning’ the trees with boron all to no avail – is this peculiar to the Central Otago environment, the cultivar [ New Zealand cultivars tend to be small when compared with North American cultivars ] , or whatever – can anyone offer any advice on this problem .Some years ago I visited a walnut processing factory in Victoria and I remember the guy showing me some nuts and saying “ These nuts are so small that we just discard them because nobody would eat them “ , sadly they were a lot larger than most of our bigger nuts !. I note that the Rex’s that are mentioned in your blog from Manawatu are not noticeably any smaller than other cultivars .
Over the last 4 years or so I have not been spraying for blight , but this year I did spray at budburst and later , and I must say that subjectively I don’t think that there was a huge difference between the two periods
My ideas of field grafting my “ wild trees “ is still in my head since I found it difficult to find suitable scion wood from my Meyrics , but I shall keep trying. So keep up the good work with your Blog. Very best wishes. Jeffrey
Thanks for your prompt reply Jeffrey.
Sorry to hear of your difficult season. Being mechanically challenged, I avoid machines as much as possible. So I use gravity for my harvesting, a hand-held hose over wire racks for my washing, and the only moving parts in my whole system is a domestic dehumidifier and fan in each drier. Of course it helps when my wife does even more than I do.
I don’t know why Rex came out so well in my crackout score, but that was the measure I got. Last year I tried hand cracking a sack of Rex nuts and found them much more difficult to get out of their shells than my seedling nuts. I am full of admiration for Jenny Lawrence making a living out of cracking those things. My Meyrics have never produced enough to give me a sack full to try cracking on their own. I also discard a fair proportion of the Rex’s I pick up because they are too small to handle.
Thanks. It is great to hear from someone like you who is pushing the boundaries.
Looking forward to hearing from you.
nick nelson parker
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