Grafting witches brooms (WB) , and other WB questions.

[Anhosustali]

Here is the list of questions there is a lot and I don't expect all to be answered, but I hope to eventually figure them out. Anything helps!
-1- In grafting a witches broom (WB), can you graft a large branch, or can I expect to only be successful with a small cutting? (I remember seeing a video of some guys who used shotguns to shoot down WB and graft them later.)
-2- What Genera exhibit genetic WB? Are there some Genera that will never exhibit WB? Is there an online list that someone has compiled?
-3- How can you tell genetic WB? Are there ways you can tell from afar? (I have spent most of my life wandering wilderness areas, I believe I have found 4 genetic WB (Pinus sylvestris, Abies concolor, an unknown pinyon-juniper, Quercus gambelii) but I would like to know if it is worth hiking up my climbing equipment to make attempt at it. I see the temptation to use a shotgun)
-4- Is it advisable to air layer instead? I am in Utah, so I am concerned about freezing developed roots in a tourniquet method.
-5- When grafting should I maintain general rules of species mixing? or because of new genetic differences is it important to maintain the species for root stock?
-6- I know this sounds awful but is there any research out there about the chemicals or processes that cause WB non-genetically, and would it be possible to apply it to the tree? Essentially forced stress.

 

[yenling83]

I've always been interested in experimenting with Witches broom to graft new foliage. You can actually purchase several different varieties of WBs in the specialty conifer industry. Here's a Ponderosa Pine WB that you can purchase from Coniferkingdom.com. I like the idea of a dwarf Ponderosa foliage grafted onto a Ponderosa trunk.

Pinus ponderosa 'Pennock Pass Pincushion'Ponderosa Pine

Pinus ponderosa ‘Pennock Pass Pincushion’Ponderosa Pine for Sale at Best Price. Free Shipping on order over $150. Shop Online from Conifer Kingdom.

www.coniferkingdom.com

-1- In grafting a witches broom (WB), can you graft a large branch, or can I expect to only be successful with a small cutting? (I remember seeing a video of some guys who used shotguns to shoot down WB and graft them later.)
I believe scion grafting or grafting small pieces is more common, however you could approach graft as well using a larger rooted plant.


-2- What Genera exhibit genetic WB? Are there some Genera that will never exhibit WB? Is there an online list that someone has compiled?
Likely most or all Pines have the ability to exhibit WBs, the more trees in the wild the greater the chances of finding.

-3- How can you tell genetic WB? Are there ways you can tell from afar? (I have spent most of my life wandering wilderness areas, I believe I have found 4 genetic WB (Pinus sylvestris, Abies concolor, an unknown pinyon-juniper, Quercus gambelii) but I would like to know if it is worth hiking up my climbing equipment to make attempt at it. I see the temptation to use a shotgun)
The area of the WB on the tree looks quite different from the rest of the tree's foliage. I'd do some googling to see some examples.

-4- Is it advisable to air layer instead? I am in Utah, so I am concerned about freezing developed roots in a tourniquet method.
Maybe a question for people in the Specialty Conifer industry. I know Jerry Morris is responsible for propagating many different varieties of WBs. I'm no expert, but I would guess taking cuttings would be the easiest method to propagate. As an air layer would need to be watered regularly and pines are challenging to air layer.

-5- When grafting should I maintain general rules of species mixing? or because of new genetic differences is it important to maintain the species for root stock?
Generally speaking any pine can be grafted onto any other pine, juniper onto juniper. Certain varieties pair easier together and the weaker the foliage type you're grafting will create a weaker overall tree, however theoretically any pine on pine is possible.

-6- I know this sounds awful but is there any research out there about the chemicals or processes that cause WB non-genetically, and would it be possible to apply it to the tree? Essentially forced stress.
I doubt this would work, I believe all WBs are just a genetic abnormality and cannot be forced.

 

[Wires_Guy_wires]

1. Agree with above.
2. All plants from the eudicot side of the plant branch. Monocots can't do this because they have no stems or trunks, but pretty much all other plants that produce branches in some shape or form, can have the genetic mutations that relate to WB.
3. By analysis only. This is expensive and will cost around 3K dollars per sample - AND you'd need to know what to look for. I've been trying to zone in on the genetic basis for stuff like cork-bark, but without proper foundational research, I have no clue as to where in the genome of any plant to start looking. With something like loblolly pines having genomes 4x the size of a human's.. I'm waiting for researchers to strike that gold for me. Once I know what to look for, I can probably get tests for less than 15 USD a sample. Some infections that cause WB can be seen through a microscope. So it wouldn't hurt to have a look to see if you can see anything that looks out of the ordinary. Bacterial infections can be hard to distinguish though, but the plant can form small capsules that you probably can identify. With fungal infections, you might be able to find streaks of discolored wood or cambium. If it's viral, you can't tell whatsoever unless you know which virus and do a genetic test.
4. If the WB is genetic and caused by a cytokinin excess, this means that auxin is probably suppressed due to their interaction. This in theory, would inhibit rooting. But as with the long standing idea that auxins are only produced in the shoot tips, things can change with new scientific findings. It's been shown a couple times that roots themselves can produce auxins as well, and don't always rely on growing branch tips. The interaction is more difficult than even scientists expected it to be. There are some theories that haven't changed since Darwinian times, but as they're being investigated, it turns out that there's a rabbit hole to be found.
5. Yes, keep them as close to the rootstock as possible, for both aesthetic as well as practical reasons.
6. Yes. There are a number of hormones that have long lasting effects and can be used succesfully. However, they have been tested in laboratory situations and usually just on a couple strains and wildtypes. This gives you a general idea of what to expect, but I speak from 10 years of experience when I say: it's unpredictable! 6-Benzylaminopurine is a strong cytokinin, as is zeatin found in corn. When dosed in excess, the treated plants can produce WB-like growth for a couple years.

Welcome to the wonderful world of plants. Welcome to yet another rabbit hole to dive into ;-)

 

[Anhosustali]

Wow so interesting! Thank you both for answering them all. I had no idea WB developed due to excess cytokinin. Do you know of any research papers about the tests you're talking about? Also, how would I treat the plants with cytokinin? Topical, or through the soil? It's also interesting about the genome, it makes me curious to what degree can we selectively breed a dwarf/WB plant for each tree? Is it fantasy? So cool! I am very willing to fall down this rabbit hole.

 

[Wires_Guy_wires]

I don't have any research papers on the subject, but if you go to scholar.google.com you can probably find a bunch of papers if you search for witch broom + plant name.
Treating plants with cytokinins can be done in all kind of ways, topical and through the soil. The key is to know what concentration if effective, and this can usually be found in literature; "adventitious shoot formation in vitro" is usually something researchers describe in in vitro protocols. Which is usually the basis for tissue culture of a plant. Use that same concentration and add a few milligrams.

Selective breeding can be done, but breeding does take whole generations. Most pines for instance, take a couple years to reach adulthood. Breeding them for two generations can possibly take 20 years. And you'll need two generations at least to find dominant and recessive traits. Numbers also play a role; the bigger the group, the more data you produce and the larger your selection pool can be. And also the more traits you'll find.