Woody Plant Root Cutting Propagation

[MikeH]

First of all, I have to thank Tim again for putting me on to Dirr and Heuser's The Reference Manual of Woody Plant Propagation: From Seed to Tissue Culture. It is a remarkable book and invaluable to anyone attempting woody plant propagation.

I used the technique twice this year, once to propagate sea buckthorn plants which are virtually impossible to propagate from soft or hardwood cuttings. They germinate well from seeds but you have to wait a number of years until they produce flowers to determine whether you have male or female plants. A bit later in the spring, I used the technique again to propagate beach plum and hazel.

Charles Heuser spells out the problem with the root cutting technique: The inconvenience of securing root cuttings is a strong deterrent. Either the whole plant must be dug to secure appropriate root pieces or else the soil must be excavated around the plants to expose the roots. Either method is tedious, labor intensive and usually must be carried out during the fall and winter months.

I think that I've figured out a way around this problem - portageperennials.wordpress.com/2012/06/20/more-thoughts-on-root-cuttings/

Now I just have to try the technique enough times to learn and hopefully master its subtleties. Probably needless to say but I think that this technique is fantastic for reproducing difficult-to-reproduce or expensive plants.

[raymondo]

I hadn't considered root cuttings for trees and shrubs. In fact, the only plant I've ever propagated this way is comfrey. Must give it a try.

[oxbowfarm]

Wow, that's great Mike. Especially the Sea Buckthorn. I have dreams of a Sea Buckthorn planting myself... there is never enough time.

[MikeH]

You have to be really, really patient. Last night, I was cleaning up my plant shelves and decided to toss out apparently failed root cuttings. I dumped out a persimmon rootstock cutting and found an underground shoot about 1 1/2" long and 3/16 to 1/4" in diameter. I was so surprised that I put in back into the pot without taking a picture. I then dumped out a quince rootstock cutting and found new root growth but no shoot development. Forgetting to take a picture again, I quickly stuck in back in the pot. Needless to say, I left the remaining cuttings undisturbed. Anything that does come of these cuttings will probably need to be overwintered inside.

I'm pretty sure that the persimmon rootstock is Diospyros virginiana because the cultivar grafted on to it is an American persimmon. According to the California Rare Fruit Growers, D. virginiana ... suckers badly. That makes it a prime candidate for propagation by root cuttings.

Since Cydonia oblonga can be propagated by stooling and trench layering, it's also a good candidate for propagation by root cuttings.

I think it's a useful technique for dealing with nurseries who don't know or won't talk about the rootstock on the trees they sell. If I can propagate the rootstock, I don't particularly need to know exactly what it is. I'm not looking to take bread out of the nursery's mouth by competing but I am interested in trading scionwood and in protecting my original investment by cloning it.

It's such a little used technique that the International Plant Propagator’s Society doesn't have much in the sixty volumes of its proceedings dating to 1951.

I think that one can have good success with any tree/shrub that suckers or can be stooled/trench layered. That's not to stay that other trees/shrubs can't be propagated that way but it would be a case by case determination.

[MikeH]

When I replanted the persimmon on 6/30, I left maybe 1/16" of the shoot exposed to the light. Since then that shoot has grown a good 3/8". The pot is tented but it only gets direct sun early in the morning up until 10:00 am. Nonetheless, the black pot causes the soil to warm up quite a bit. Inside the plastic bag, it's like a tropical rain forest - moist, humid, and warm. I don't know if this has any significance but it's worth noting the observations.

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[raymondo]

I potted up some jostaberry cuttings I set last year and used the root trimmings to try a few root cuttings. I have no idea whether jostaberries can be propagated this way but it's fun to try. The roots were on the thin side so there may not be enough in them to produce a bud, even if they could.

[MikeH]

Jul 4, 2012 5:56:13 GMT -5 raymondo said:

I potted up some jostaberry cuttings I set last year and used the root trimmings to try a few root cuttings. I have no idea whether jostaberries can be propagated this way but it's fun to try. The roots were on the thin side so there may not be enough in them to produce a bud, even if they could.

Since it's a Ribes, waving any part of the plant anywhere near a growing medium will result in fruit within minutes. ;D Based on the growth I've seen by sticking black currants and gooseberries, I'd imagine that root cuttings would work. If not, from black currant and raspberry experience, tip layering works.

[raymondo]

Jul 4, 2012 6:36:21 GMT -5 MikeH said:

Since it's a Ribes, waving any part of the plant anywhere near a growing medium will result in fruit within minutes. ;D Based on the growth I've seen by sticking black currants and gooseberries, I'd imagine that root cuttings would work. If not, from black currant and raspberry experience, tip layering works.

Yes, I've had no trouble with straight cutting from the jostaberry, or red currants I've tried in the past. It's only a question of whether the root has enough reserves to be able to produce a shoot.

[MikeH]

The persimmon root cuttings have progressed well-ish. It's been a tough summer. Although they had plenty of water and protection from direct sun, it's almost as if they sensed the drought and slowed their growth accordingly. Since the rain we've had, they've put on more growth.



The two beach plums have done very well and had to be potted up to 6" pots.

[ottawagardener]

These are beautiful by the way Mike.

[MikeH]

Both the persimmon cuttings ultimately failed. Leaves but no roots. It happens. But my Russian almond and Yellowhorn cuttings are putting up a good fight on the windowsill. I had both bagged to retain humidity in the dry winter air and nearly lost the yellowhorn to mildew but I unbagged it and it has put out new growth. Now the Russian almond which was doing really well is looking a bit sketchy. Just shows that the more I think I know, the less I do.

Peter Del Tredici, senior research scientist at Harvard's Arnold Arboretum has written what I think is the best piece on root cuttings. It provides history, techniques, and a list of species that have been propagated by root cuttings. Although it's nearly 20 years old, I've not seen anything better.

[raymondo]

Pity about the persimmon Mike. I've had several goes at growing scion stock from cuttings and I often get good top growth but nothing underground. I haven't tried rooting hormone though.
My root cuttings of jostaberry and peach rootstock amounted to nothing. Neither surprised me. The jostaberry cuttings were, as already mentioned, rather thin and I doubted there ability to produce a bud. The peach rootstock doesn't sucker so no surprise there.
Just as one can use rooting hormone I wonder if an application of something like gibberellin would stimulate shoot formation.

[MikeH]

Dec 6, 2012 15:51:21 GMT -5 raymondo said:

Pity about the persimmon Mike. I've had several goes at growing scion stock from cuttings and I often get good top growth but nothing underground. I haven't tried rooting hormone though.
My root cuttings of jostaberry and peach rootstock amounted to nothing. Neither surprised me. The jostaberry cuttings were, as already mentioned, rather thin and I doubted there ability to produce a bud. The peach rootstock doesn't sucker so no surprise there.
Just as one can use rooting hormone I wonder if an application of something like gibberellin would stimulate shoot formation.

If you are trying hardwood or softwood cuttings, yep, they can be tough. I am surprised that your peach rootstock root cuttings didn't take. Did you take the cuttings when the tree was dormant? That's important because you want to capture all of the stored food in the root. When dormancy is broken, this stored food results in an energy burst of growth. Were the cuttings taken from close to the trunk and did they have tiny capillary roots on them? Did you maintain polarity? The proximal end (nearest the trunk) has to be up.

I use PRO-MIX ‘BX’ with Mycorise®PRO which has a single mycorrhizal fungi. I wonder the extent to which mycorrhizal fungi helps with root formation.

I've never used mycorrhizal inoculant other than that which Charles Rhora sells with this trees. I'm going to try producing my own starting with a water-soluble form of mycorrhizal inoculant from Bountiful Gardens. The research that I've come across uses Bahia grass as a host but I've had confirmation from David Douds, a soil microbiologist at the USDA, that annual ryegrass should work just as well. What I'm hoping to do is setup an ongoing production system.

[oxbowfarm]

Mike,

Great work with the root cuttings.

A note on sea buckthorn, I was just reading the Sea Buckthorn entry in Dirr where it says that the male and female plants have very different bud morphology so you can tell them apart as seedlings. That's kind of a relief as I just planted a bunch of seeds and want to be able to pick our mostly females. This is only hearsay until I have buds to look at, I was wondering if you might mosey over to your sea buckthorn and confirm or debunk this tidbit.

[MikeH]

Well, it's a good thing that I have a map that tells me which are male and which are female because I can't tell which is which. I'm sure if Michael Dirr were to lead me by the hand, I'd figure it out quickly.

Dirr isn't the only one to say that you can tell the sex of the plants by looking at them. Wilfrid Sheat, an oldtime horticulturalist, says in his 1948 book, Propagation of Trees, Shrubs, and Conifers :

Contrary to general opinion, it is very easy to distinguish between male and female plants in the seedling stage, especially in spring when the axillary buds are very prominent on male plants and these should be separated and labelled at this period. The shoots of the female plants are quite clear and smooth at this period, so that is impossible to confuse the sexes. In addition to this, pistillate plants are distinctly more spreading in habit and growth is much more twiggy.

It would seem that sometime in the spring is when you can tell by looking at the plants. Sea buckthorn seems to be a pretty weedy looking shrub/tree so more or less twiggyness is probably in the eye of the experience beholder.

Then again, until they fruit I can't be absolutely sure that I don't have all males or all females. Maybe there are no differences to be detected in my plants. I have an anecdotally derived rule of thumb that says it generally takes a minimum of three years for a perennial - tree, shrub, vine, herbaceous - to establish itself and exhibit its full characteristics. Our sea buckthorn were bought and planted in the fall of 2009 so they are just entering their 4th season. They were 10-12" when planted and some are now 4 feet plus so I'm hoping that this is the year.