Probably out of the scale that anyone on this forum is working at, but I’m curious about how rootstocks are commercially produced at a mass scale. Big wholesale nurseries are clearly planting rootstocks in the thousands but most of the information I’ve found about rootstock production from stool beds comes from small-scale sources. I’m having a hard time imagining how that process scales up to the truly mass scale. Does anyone have any articles or videos explaining about how rootstock production is mechanized or scaled up by big growers?
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Here’s an old video from Dave Wilson Nursery that shows their fields and harvesting grafted trees. I imagine they use similar techniques for the rootstocks. Heavy machinery like the GK digger to get the trees out of the ground, and a lot of manual labor to pull the loose trees and load them up. Just from a scale point of view I would think they probably use rows for stooling and they wouldn’t be permanent but probably starting new rows after harvesting. It would be interesting to see what they actually do.
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Of course some of the clonal rootstock I’ve purchased like bud 9 has long stringy roots that look like they were grown in pots. I wonder if there is an element of greenhouse production to some rootstocks?
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Yeah, I guess to grow rootstock in rows you would plant existing rootstock varieties at a severe angle, periodically deposit mulch or growing media on them, then after a certain period dig them all with a big digger and hand-separate the new rootstocks? Seems like a lot of hand-work involved for a cheap product but I’m not sure how you could mechanize it further.
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Your question is definitely beyond the scale I have needed to produce. So far.
However, there are books about plant propagation (university textbooks; weighty tomes with abstruse verbiage) that I looked over when learning to graft that explained methods utilized on any scale.
One method standing out in memory was to plant a rooted whip & lay it on newly worked soil (no competition from other things growing), with or without scoring the underside & dusting rooting hormone powder or daubing hormone gel along that underside. Pin it down here & there & watch each leaf/twig node become a source of roots/suckers. Lay a five foot whip down & find 5-8 new suckers from each node. I can see this working easily with Budagovsky118, which will send up scores of suckers from the root of a mature tree cut to the ground.
For stock that sends few suckers from the base when cut to the ground, such as Geneva30, this method would be worth a try. If it works, it might make 30.
I have used root suckers that came up from trees that failed the acid test of life in my back yard. Gen30 sends no suckers as long as it has a viable cultivar atop it - one if its many attributes, in my view. For commercial root stock makers, that is a problem. If I were to make many Gen30, I’d lay some whips down & see if that idea works. If it does not, then I’d plant as many stocks as can yield the number of stocks projected to be needed the next year, basically a ration of 1 to 5.5, the average I have seen here.
This region is increasingly hot & dry June-September & this soil is sandy & poor. My principal goal is apples nearly year-round, grown without using poisons. Believe it or not, these conditions allow me to do that (shh, folks east of the Mississippi don’t like to hear it, understandably so). These conditions also thin the numbers of cultivated varieties (cultivars) succeeding to yield delightful fruit. Too often all flavor &/or moisture leaks out the skin in the low oven temperatures apple trees must contend with here. My secondary goals have been historical interest and interesting flavor. The result after 17 years of trial & error is a home orchard with some older apples (Maiden Blush, Lamb Abbey, Claygate) producing well & three European plums.
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Im not 100% sure on the colonal process of root stock, but I would imagine they use rooted cuttings or stool beds.
What I got this spring I would say stool beds as they weren’t all that heavily rooted.
As far as beds. They have planters that will plant them out at your desired spacing usally 4-5 rows. 8-12" apart.
At harvest they use a bed lifter which works like the GK machine but it cuts under the bed and isnt for a single row. Typically pulled by a high clearance tractor with a creeper gear. This cuts the roots, lifts and shakes the plants somewhat free of soil.
I attached a pic of one we used for nursery stock harvest where I used to work.
Hope that helps. Not exactly about clonal rootstocks but how things work in commercial bed production of liners.
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In terms of massive mass production of rootstock, the most productive way is probably tissue culture.
Once I was given a full tour of the internal workings of Sierra Gold Nurseries, and they propagated their rootstocks via tissue culture. From what I could remember, they had at least 13 tissue culture stations being work by Indian women (women have better dexterity), and a whole slew of giant climate controlled rooms of tissue culture plants rooting in vitro. We walked down the aisle of one of them as our guide pointed out large sections comprised of each prunus rootstock. Sierra Gold Nurseries kick out many millions of finished, grafted trees annually.
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Tissue culture would have been my answer also. It takes much less room/acreage and results in healthier rootstocks. Field grown rootstock would be exposed to crown gall and lots of other potential issues even before they’re grafted. With tissue cultured rootstock, greenhouse propagation and grafting, you’d have a healthier tree grown in mass in a few acres of greenhouses vs a hundred or thousand acres in the field.
Think about planting a hundred or thousand acres of almonds, walnuts, or peaches. Would it be easier planting small potted trees or big bareroot stock. The pecans I planted this spring needed holes 24 inches deep.
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The narrator does a pretty good job of describing the process…
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For grapes, which are easier than rootstocks for other fruit since they root from cuttings, rootstock mother vines are grown in fields and allowed to sprawl, either on the ground or onto a trellis:
A machine is used to cut the dormant canes from the mother vines:
The canes are cut to the same length by hand (you can see the workers in the background of the previous pic) and tied into bundles for grafting:
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Fantastic thanks! Seems like a very specialist piece of equipment-I wonder if all the big producers use something similar or if there is a bit of a spectrum between here and the largest growers.
I have been continuously amazed at the adaptability of horticultural producers to “borrow” equipment from other industries and figure out how to use it for their purposes.
Ever see a snowblower used to grow trees? Specifically, to heel in for winter storage.
I also get constant reminders that when I went to college, the highest paid starting salary in the university went to ag engineering. These guys made macguyver look like he was playing with tinker toys and Lincoln logs.
Simply put, as you scale up a production system, you develop a systems approach. It’s like explaining high density orchard planting to someone who wants standard trees. It’s a different way of approaching the way things are done.
One of the things that makes the horticultural industry so vibrant is the range of approaches you will find. Old school practices exist side by side with cutting edge technology. What do you want to find? Because you will find it.
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A row of “trees” growing in a field, cut off very low. They send up lots of “suckers”. Later dirt is mounded against them so that the lower parts then also grow roots. That machine is cutting off that “sucker” below the surface. The mother plant is still there, to send up more “suckers” next year and start the process over. Same process for large or small quantities, I’ve done this in my home orchard. I just used a shovel and cutters on a single tree, as opposed to a tractor 
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Thats what I do. Various parts of the yard you see 5 trees close together mounded with dirt. M111, P.2, B10, M26 and B118. They do not get the same level of care. Survival of the fittest and all.
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