Join ACS
Member Login

Home \ Discussion \ General Discussions \ Grafting understock decisions…

Grafting understock decisions… (9 Replies)

Posted February 12, 2015 at 8:07 am

Recently, I’ve taken an interest in grafting and in understock choices for grafting, and why some things are used and some aren’t. There are the traditionals — Picea abies for Picea grafts being the most popular; a variety of choices for Pinus grafts dependent on the number of needles and the regions, with certain pines being pretty much the go-to standards; a few different Abies species for firs; etc.

What makes a good understock? Is it JUST viability in the region and perhaps availability? Are there particular reasons that every 2-needle pine seems to be grafted onto one of only a few different pine species (sylvestris, thunbergii, contorta) with dozens of species to choose from? I’ve been told, for instance, by several grafters that 2-needle and 3-needle pines are generally compatible, and I know the Texas forestry department field-grafts Pinus taeda, so why isn’t it used more often as a rootstock (as it is massively available, being the most popular timber and pulp pine)?

I’ve also read of a variety of different understocks that are graft-compatible with Chamaecyparis lawsoniana, a notorious plant on its own roots, that is so bad it’s now being sold on special and highly-marketed disease-resistant rootstock, just to keep it from dying. But people graft it onto Thuja on occasion (which is resistant). Why is that not done more often? One would think the prevalence of Thuja would make for a far less expensive alternative.

And why is not more Juniperus scopulorum, another troublesome plant in many areas, grafted onto Juniperus chinensis?

Do these decisions ultimately come down to business decisions in some way? Or do grafters pick a favourite and then never stray, as they have something that works, so why foul up the system? Or are there serious issues with straying from the tried and true?

I’m curious, as there are studies galore online in hort journals and programs that show the viability of things people never seem to use. And all the information from actual grafters I speak with seems to lie more in the realm of “this is how I do it, and it works.” Is there a rule? Or is it more along the lines of “pick something you like and that works and stick with it?”

Cancel Edit
Save
Posted February 12, 2015 at 9:34 am

Hi Neil, there are a lot of questions here. I’ll pick a couple of the points that are most interesting to me and hopefully others can add their two cents.

Certainly the choice of understock has a lot to do with what works in your area. Out west we use Pinus contorta and sylvestris because they work and seed growers produce a lot of these seedlings for reforesting. They are cheap and easy to get a hold of. It’s that simple. I feel that in the southeast, a hold new paradigm needs to be established as more hobbyists and nurserymen take on the art of grafting. (I’m delighted, by the way that this is happening). What are the reforesters and Christmas tree people growing in mass quantity? Try things out and see what works. You may end up with a better rootstock for your area. Keep in mind that you want species that naturally produce a spreading fibrous root system instead of a tap root. Not sure if this is the case with P. taeda.

Sometimes for understock, I just wander into the woods and dig my own seedlings and plant them into band pots for the next year. I get 100s of Pseudotsuga menziesii understock that way for free. What’s out there for you?

For Lawson cypress, there are a number of understock options that will work (for a short time). Although you may get some takes using various Thuja and Platycladus species, they will all likely be weak and crap out after a few years. Best long-term solution is Ch. lawsoniana DR understock. (Yes, I know it’s expensive and hard to acquire).

Cancel Edit
Save
Posted February 12, 2015 at 10:43 am

Pinus taeda adapts to its soil drastically. In sandy or loamy soils, it will produce a tap root until it finds purchase. But in clay soils (like we have here), it will produce only a short one and then begin work on a spreading, lateral root system. This has actually been an issue in some locations, as it has an impressively fast vertical growth that can lead it to outpace its ability to stay in the ground in heavy winds. I have read, however, that its growth doesn’t really change the characteristics of its graft. A slow-growing graft will still remain slow-growing. Pinus sylvestris does beautifully here given plenty of water. As do some variants of Pinus strobus (which is often used for 5-needle grafts). But I’ve never, for instance, seen someone graft onto palustris, echinata, or elliottii in the industry, despite their ubiquity (the forestry departments in these areas practically give them away).

As for Xmas trees, the most popular in the South is still Abies fraseri, which doesn’t grow anywhere other than the upper mountains. For ‘grow in the ground’ trees, we see a lot of Cupressus leylandii, Juniperus virginiana, Thuja occidentalis, Picea abies, and, somewhat recently, Cedrus deodara. Once in a while, we’ll see something unique like a Cupressus leylandii ‘Silver Dust’ or a Picea omorika. But those are rare for in-ground. And even with all those options, Abies fraseri is still 95% or better of the Xmas tree trade here. All shipped in, cut, from North Carolina.

As for DR lawsoniana… I think there’s a fine line between ‘hard to acquire’ and ‘impossible to acquire.’ ūüėČ

Cancel Edit
Save
Posted February 12, 2015 at 4:17 pm

For whatever it’s worth, the lawsoniana I acquired on “disease resistant” rootstock died about six months after I planted it. I don’t have proof, but I suspect disease.

I can’t answer any of your questions, but as a southeast conifer gardener, I’ve quickly learned not to buy a plant unless someone can tell me what rootstock it’s on. Please let us know what you learn.

Cancel Edit
Save
Posted February 12, 2015 at 10:55 pm

I have a lawsoniana ‘Ivonne’ on DR rootstock that’s doing very well so far. It went from a 1 gallon to encircling a 3 gallon pot in a matter of months, which tells me its roots are kind of insane. Plopped it in the ground, and it’s survived some crazy weather over the last couple of years. Record rainfall last year, and a 5 month span with not a single drop of rain this year (supplemental watering only). I have hopes for it. But there are, apparently, several variants of DR rootstock for lawsoniana. This one is Guardian (TM) if that makes ANY difference.

Cancel Edit
Save
Posted February 13, 2015 at 8:06 am

I got my first lawsoniana on DR rootstock last month – a ‘Wissel’s Saguaro’ that came from Buchholz. Supposedly Conifer Kingdom is grafting onto DR rootstock as well. I am not going to get another lawsoniana unless it’s on DR rootstock. I watched two gorgeous ‘Golden Showers’ die as well as a darling ‘Rimpelaar’. I can’t swear that it was Phytopthora, but that is what is likeliest. I fear for the other established lawsonianas in my garden; there are heavy layers of mulch around them to reduce the chances of muddy water splashing on them. But maybe I’m kidding myself and Phytopthora can live in the mulch as well.

Cancel Edit
Save
Posted February 13, 2015 at 9:04 am

Hi Sara, keep in mind that Pytophthera lateralis is a water-borne fungus that destroys the roots. I’m not sure that it is spread through splashing around in muddy water. (Although I have seen soles of footwear implicated in at-risk areas).

Cancel Edit
Save
Posted February 14, 2015 at 7:42 am

I can’t stand Bucholz, yeah they have nice things, but that man is one piece of work

Cancel Edit
Save
Posted February 14, 2015 at 8:36 am

While this is still getting off topic even further, while we’re on the subject of Phytophthora, I’ve read many studies dating back decades about the use of both phosphonate/potassium phosphate fertilisers and antifungals on boosting the immunity response against Phytophthora tremendously, allowing many plants to essentially fight it off. Has anyone experimented with conifers in areas they normally have issues to see if it can be used to help borderline cases?

Cancel Edit
Save
Posted February 14, 2015 at 2:10 pm

Dave I understand that but I have always been told to avoid splashing muddy water onto the foliage. I wonder if we can find someone to clear this up for us. Neil I have no idea. I stay far away from phosphorus because I have so many Australian plants. Australian soils are very low in phosphorus and the plants have evolved to deal with it. The easiest way to kill them is to have too much phosphorus in the soil. As Gilda Radnor said, ‘It’s always something!’
Sara
ps now really off topic! Neil thank goodness you took us there as you are the OP and the one that should be irritated!

Cancel Edit
Save

You must be to reply to this topic.

Iseli_20120921_3877