Walnut species hybridization project

[Jeremy Weiss]

Hi all,

I now have most to all of the seeds for my proposed walnut hybridization project; making a hybrid cross between Hind's Walnut (Juglans hindsii) and the Manchurina Walnut (J. mandishrurica) .

The goal of this cross is, naturally, to get the best of each parent.

 From Hind's I want its unusual (for a not regina walnut) tendency for producing nuts which are comparatively smooth of shell (which makes cleaning them for storage MUCH easier than it is for say J. nigra)

From the Manchurian I want it's EXTREME cold tolerance (it can take temperatures so low it can comfortably grow in Southern Alaska). Hopefully this will offset Hind's tendency (being from North California)  of being a little cold intolerant.

As far as I can tell, the actual crossing   should be pretty easy. Both parents cross readily with J. regina (TOO readily in the case of Hind's where it is now hard to find pure stock) so they should have no problem with crossing with each other.

The only hard part (as I see) or rather time consuming part, will be growing the trees from nuts (plus eventually working out how to graft them, as I am not adroit)

Wish me Luck!

[Garrett Schantz]

I would buy grafts from somewhere. Walnuts usually don't produce nuts until they are around 10 – 13 years old from seed. Grafts are around 5.
 The F1 should be all pretty much uniform, but that is another 10 - 13 years. After that you would have to plant out the F2, F3 which is where you would begin selecting out traits. Walnuts can cross freely as well. So you would need to plant the offspring in a different location each time to prevent segregating backcrosses.

 Suppose problem with buying them would be lack of availability. Watershednursery sells Juglans hindsii potted, but it is out of stock and I am unsure of how old the plants are. Vdberk sells J. mandishrurica.
 Another problem is that the crosses probably won't be as cold tolerant as mandishrurica. Crosses with cold hardy species of orange have shown this, as have tamarillos and other species.
 This could possibly be fixed with backcrosses, but this could be annoying as you will probably need to select for larger/smoother nuts which mandishrurica backcrosses could eliminate.
 
 Sounds time consuming, but good luck.

[Jeremy Weiss]

Well, my hope was that, by the time the seedlings were graftable, I'd have worked out how to graft one onto the other (preferably Hind's onto Manchurian, as it makes more sense to have the tougher one be the one with the roots) (or I can use the black walnut I already have as the rootstock and save myself more time). And keep grafting each time to speed things up. (at least until I start selecting, in which case I have to graft each one to it's own rootstock and segregate them, as you said)

It's the loss that is why I picked mandishurica as opposed to nigra or another North American walnut. I'm hoping for an average; something that will take down to maybe zone 4.

Not sure size you be a problem as Mandishurica nuts are about as big as Hindsii. Pitting seems to average out, based on what I have seen of Mandishurica Regina hybrids (I don't need something perfectly smooth, just something where the pits are shallow enough you can empty them out with a scrubbing pad.

With the Watershed Nursery trees, I'd also be worried about purity. A lot of Hinds trees are so full of Regina DNA they're functionally Paradox walnuts. Paradox is a perfectly fine tree in and of itself, but I worry that, as Regina isn't all that cold tolerant either it would drag the total down.

[Richard Watson]

Can you fella's tell me how to grow the nuts, I try recently with no luck.

[Garrett Schantz]

Manchurians are described as having a thick shell.. Wikipedia says this about Manchurians "The kernels of the nuts are edible, but small and difficult to extract"

 Can't find much information about hindsii's thickness or anything. Usually the wood is used, assuming the lack of information about the nuts is because they probably aren't harvested. There is apparently only one pure stand. I'm sure more have been planted.

 I usually plant them in the ground at the end of the season, but for New Zealand you will probably need to try cold moist stratification for about 2 months minimum. Scarification might work better for thicker shelled species.

[Jeremy Weiss]

Hindsii are pretty thick too. Like a Black Walnut, you need a hammer to break it.

As for more being planted, yes an no. In California, Some growers use Hinds as a rootstock for Regina. If those rootstocks develop branches, it isn't unusual to get Hybrids reminiscent of Paradox (the Hinds Regina cross developed by Luther Burbank as a street tree). But Hinds on hinds isn't all that common.

Also check what your climate it. A lot of Walnuts don't like it too hot either. I have no idea how hot South Island is. But if it is more tropical, you may do better with one of the South American Walnuts, like J. boliviana, J.peruviana, or J. chilense.   

[reed]

Can you fella's tell me how to grow the nuts, I try recently with no luck.

What kind have you tried? I'm mostly only familiar with our wild black walnuts and a little bit with store bought English walnuts, both sprout and grow easily just planted in the fall and covered with a board or rock till spring.

I really didn't know there were so many different kinds.

[Richard Watson]

I didnt know there were so many kinds either.

The nuts came from a local tree that produce large shells that could be pulled apart by hand. I was told to remove seed from the nut, sow in autumn and let the winter frosts do the stratification, but nothing.

[Jeremy Weiss]

Well, first of all, you shouldn't be removing the nut from the shell (actually, if you CAN remove a walnut from it's shell without it breaking into pieces, I'm impressed*.) The naked kernel is more or less guaranteed to rot.

If you can pull apart the shells by hand (assuming you mean the shells, not the husk) it sounds like you have an English or Persian Walnut, J. regia the same kind as is grown commercially.


* assuming that it is an common walnut the kernel should look sort of like two brains attached to each other. If it looks like a puffy heart (i.e. does not have any bumps on the kernel) then what you have is either a Japanese Walnut (J. aliantifolia) or it's subspecies, the heartnut.

[Andrew Barney]

Good luck on your project!

There is a hybrid walnut sold by a company in England that sells a hybrid between the american black walnut and the typical eating walnut I believe. Someday I want to purchase a few.

https://www.walnuttrees.co.uk/shop/walnut-timber-trees/ng23-hybrid

https://www.walnuttrees.co.uk/shop/walnut-timber-trees/mj209-hybrid

[Richard Watson]

Well, first of all, you shouldn't be removing the nut from the shell (actually, if you CAN remove a walnut from it's shell without it breaking into pieces, I'm impressed*.) The naked kernel is more or less guaranteed to rot.

If you can pull apart the shells by hand (assuming you mean the shells, not the husk) it sounds like you have an English or Persian Walnut, J. regia the same kind as is grown commercially.


* assuming that it is an common walnut the kernel should look sort of like two brains attached to each other. If it looks like a puffy heart (i.e. does not have any bumps on the kernel) then what you have is either a Japanese Walnut (J. aliantifolia) or it's subspecies, the heartnut.

  The kernel was a brain shape and was simple to remove from the shell in one piece.

I will get more seed again May next year and try again.
 

[Jeremy Weiss]

Hmm, that variety must have really papery inner walls.

[orflo]

The juglans regia walnuts need moisture and germinate even if the temperatures aren't too high.  I harvested mine about six weeks ago, placed them in tubs, outside, in the back of the garden, to avoid a rat infestation, and they started to germinate now  in these tubs, after these six weeks or so.  We had some colder nights (maybe 4 or 5), but day temperatures were also unseasonally high. So I suspect they don't need stratification.  The ones here are very hard, but clearly j. regia.  I use a bench screw to crack them, a hammer works as well but the result can be quite a mess because they do need a hard blow...I could send you some , Richard, but there could be import restictions for these, and secondly, they're no fun to crack (but very tasty!),
Frank

[galina]

I would buy grafts from somewhere. Walnuts usually don't produce nuts until they are around 10 – 13 years old from seed.

I know absolutely nothing about walnuts, but I watched a chance seedling at a neighbour's garden produce nuts 5 years later.  Was that a fluke?  Definitely not a grafted walnut.  Good luck with the project.

[Richard Watson]

The juglans regia walnuts need moisture and germinate even if the temperatures aren't too high.  I harvested mine about six weeks ago, placed them in tubs, outside, in the back of the garden, to avoid a rat infestation, and they started to germinate now  in these tubs, after these six weeks or so.  We had some colder nights (maybe 4 or 5), but day temperatures were also unseasonally high. So I suspect they don't need stratification.  The ones here are very hard, but clearly j. regia.  I use a bench screw to crack them, a hammer works as well but the result can be quite a mess because they do need a hard blow...I could send you some , Richard, but there could be import restictions for these, and secondly, they're no fun to crack (but very tasty!),
Frank

Thanks for the offer Frank but they are a restricted variety here. Besides walnuts are so common meaning there lots to select seed from. I'm keen to get some of these easy opening nuts to grow