I have a black walnut that produces excellent nuts and I would like to start the lifelong project of developing an even better tree from it. The nuts it produces are large and taste great, at least compared to other wild trees in my area, and the tree produces a large crop every year despite suboptimal growing conditions. I do also plan on grafting this tree in the meantime.
Seeing as there are plenty of wild black walnuts in the area to pollinate with and muddy the trait pool, I figured the first step would be to isolate some of the flowers this year and manually pollinate it. This way, the trees that grow from this mother tree are a mix of its traits, rather than 50% random. Since walnuts are wind pollinated, how would I go about protecting the female flowers from cross pollination with neighboring trees? Would I just paper bag the male and female flowers before they open so I can collect and manually pollinate them?
Correct. You would bag both your female and your male clusters prior to bloom, and if your male bloomed to early to use the pollen fresh, you could collect, dry, & freeze pollen for future use. I’m not sure from your post if you’re looking at self pollination, but be aware most nut crops do better when outcrossed than when self pollinated. Better to find another tree you like also to use as the male.
Your tree may be better than the average black walnut in the area but may be far less than known and highly selected varieties already available. For example, Thomas, Neel #1, Sparrow, and Farrington are highly likely to be very good varieties for your climate. Don’t exclude your tree, but be aware it is highly unlikely to be as exceptional as you currently think it is.
Forcing your tree to self-pollinate is not something I would recommend and may be physically difficult due to heterodichogamy. Inbreeding plants in Juglandaceae Juglandaceae - Wikipedia generally results in poorly filled nuts, seedlings lacking vigor, and various disease susceptibilities. If the tree has overlap between pollen shed and pistillate receptivity, self-pollinizing can occur. If male catkins release pollen earlier, little or none may be available when pistillate flowers become receptive. Vice versa, if pistillate flowers are receptive before pollen is released, no cross-pollination is possible.
What would I recommend? Grow seedlings and graft them to improved varieties. Within a few years, you will have natural pollen available which can be used to pollinate your native tree. I would suggest the four named above but could give better recommendations if you are willing to provide your location.
For an example of probability of finding an exceptional black walnut growing wild, I’ve searched 10’s of thousands of trees throughout the Alabama, Tennessee, Mississippi, and Georgia region. I found 3 trees in the last 40 odd years which are exceptional enough to be worth grafting in my planting. One of them produces clusters of up to 6 nuts. One produces on lateral branches which significantly increases total production. One is twice the size of most native black walnuts. Even though these trees are exceptional natives, none of them are better than Thomas which was found near King of Prussia Pennsylvania nearly 150 years ago.
A woman who lives in Killen Alabama wanted me to look at a black walnut growing near her home a few months ago. We found a few nuts and sampled them. They had very good flavor, nice brown/tan color, and were about 20% nutmeat which is average for black walnut in this area. I would have rated it 2 or maybe 3 on a scale of 1 to 10 where Thomas is maybe an 8.
Thanks for the insight, I was not aware that self-pollination produced sub-par trees. I haven’t had personal experience with any of those cultivars, but I have seen them mentioned repeatedly online.
I’ll crack a few and measure out the meat/shell ratio to see if this tree is competitive. I’ll probably go through with this project even if it is not, just for the hell of it. Though I’ll probably choose to cross with an easy to crack cultivar instead of self-pollinating, these nuts are as tough as any wild trees.
I cracked 15 nuts to get a rough average of the nutmeat content, which came out to 21%. These nuts are also the easiest to crack of any seedling black walnut I’ve found, but they’re still a pain. It produces quite heavily which is to be expected from an ~80 year old tree, and the very few nuts are bad (I don’t even bother floating them).
What I’ve read about the Thomas cultivar ranges from 20-35%, and that they’re relatively easy to crack. Seems like I have a decent wild tree, but probably not cultivar worthy.
Thomas generally rates 22% nutmeat vs shell. It is very well filled with a shell that tends to crack out quarters. Also, the shell is very well sealed which helps prevent darkening of the pellicle.
Some walnuts have been selected that are as high as 45% kernel. All of them so far have been poor producers meaning they don’t make enough nuts to be commercially viable.
What do you mean by “well sealed”? Do Thomas nuts come out cream colored like a green-hulled walnut, no matter how long the hull rots? I always figured the rotting hull juices soaked straight through the shell, rather than seeping in through cracks.
Suture lines and cavities in the shells permit husk juice to seep in and darken the pellicle of most black walnuts. Thomas is better sealed and takes longer to darken. I’ve seen a couple of wild walnuts with similar tightly sealed shells. It is a very rare trait. Stoker walnut has a nearly white pellicle.
Thomas also has a very loose husk which does not tightly adhere to the shell of the enclosed walnut. Emma K by comparison has a very tightly attached husk. Emma K darkens very rapidly because it also has a loosely sealed shell.
From what I’ve seen, cultivar black walnuts make pretty good offspring. If they get pollinated by another cultivar quality nut, the chances of the progeny being as good or better than the parent are quite good.
It’s worth mentioning that most walnut cultivars were wild selections. Thomas came from King of Prussia PA. Vandersloot came from Muddy Creek Forks PA (right up the road from me). Farrington from Michigan. Hare came from Rushville Illinois. Rowher from Grundy Centsr IA. Myers came from Brookville MD. Virtually every one of these locations is near where a nut grower lived, so theres an element of coincidence to this thing.
There’s a black walnut on the edge of my property which could be worthy of propagation, or at least use in a breeding orchard. I don’t usually invest much energy into black walnuts, and certainly not wild selections, but I will say I’ve found a handful of really good nuts out there. I don’t think they are that uncommon. There are also other Pennsylvania nut growers with really good wild seedling black walnuts, unrelated to the grafted trees they have.
What do I mean by a good nut? Cracks easily so you can extract quarters and halves (kernels). Relatively thin shells. Good flavor.
If you are looking at the whole picture though – issues of productivity, consistency, disease resistance, climatic and ecological versatility, and storability, in addition to crackability and flavor, that’s a much narrower subset of the cultivar genepool and requires a lot of testing by a lot of different growers with years of observation. And that’s why old cultivars like Thomas are so trusted.
Thomas throws a high percentage of good quality seedlings of which I have a few. None of them are consistently better than Thomas. Neel #1 (from West Virginia) is one of the very best but is not quite as consistently productive as Thomas.
One of the best wild walnuts I’ve found is on Natchez Trace at Burns Branch just south of Nashville. It would easily qualify as one of the top 10 and that includes about 35 selections I have grafted. Filter this a bit by considering I’ve found 3 wild walnuts worth propagating in the last 45 years. I found the tree at Burns Branch in 2018.
Well I am in Pennsylvania, so I guess that increases the odds of having a good tree.
Since we moved here a few years ago, it’s been very obvious to me that this tree is different than the other similarly sized walnuts in the area. It leafs out, blooms, and loses its leaves a few weeks earlier than the rest. The nuts are also more ridged, larger, and have a slightly different internal structue. Because of its differences, I’ve always wondered if this tree was deliberately planted by the original owner some 80-odd years ago. Either as a seedling of some other tree, or some grafted cultivar.
Sparrow - Illinois
Shessler - seedling of Tritton, ohio
Thomas - Pennsylvania
McGinnis - Nebraska
Neel #1 - West Virginia
Surprise - Missouri but is a seedling of an unknown cultivar
S127 - Iowa
Lambs Curly - Michigan
I could go on for about 30 more. There are good walnuts to be found just about everywhere black walnut grows.
