I'd like to ask for input/opinions on rootstocks. I've always purchased mine from a grower in the northeast. I've purchased both bareroot and plug and decided that, should adverse conditions hit (like the 27" of rain we had last December) that bareroot handled it better. Is anyone else seeing the same thing? Also, the material I order is very uniform. A friend of mine ordered from someone else and received a shipment showing a huge variety of leaf expression. (maybe not pure a.p.?) Would this affect grafting? Any thoughts would be appreciated.
I have mainly gotten plugs from Heritage Seedlings. So far the plants are quite uniform. I try to get the largest diameter I can. We had some nasty freezes early in the winter and I can definitely tell it affected the rootstock. I lost a lot of grafts because of it. I have gotten some of the "mixed" rootstock of variable / questionable seed sources and I much prefer the professionally grown, uniform type. The stems are straight and have long internodes, which makes them ideal for grafting.
K4, are you saying that some of the under stock is hardier than others? That would represent an important source of variability in my view. Do you know how they get the relative uniformity? Given the many expressions of seedlings this would seem difficult to achieve (although I can imagine selected species trees, isolated from any other maple, might do it. Do you consider vigorous long internodal growth ideal for grafting a drawf scion, doesn't it tend to exaggerate node length in the grafted plant? cheers, -E
Not sure about hardier. My deaths may have been due to the amount of cold exposure a particular plant got. However, since these are seed grown plants, that possibility of variability exists. Uniformity I would assume comes from a relatively homogeneous group of mother trees, and I would think they were somewhat isolated from other varieties/species to get that consistancy. The only cultivar I've heard of that is known specifically for seed production is Heavy Seed. Maybe there are others? And I'm not sure about the internode question. That's the first I've heard of it, and I haven't grafted enough dwarf plants to tell. I always assumed the internode length was due to the way they were grown (heavy fert. perhaps). I have some dwarf varieties like Tiny Tim that have pushed a foot or more this year, which is completely out of character. Fertilization seems to create long internodes, and I fertilized them this spring (lightly, mind you), so is that the reason why? Don't know at this point.
I lost over a third of my rootstock this last winter, and I attributed it to the heavy rains (27" in December, and plenty after that) but we had very cold weather, even down here in the south. I was focusing on the root system--small plus vs open larger bareroot material--as a factor. A friend/mentor of mine has convinced me that I need to focus on cultural conditions instead. He felt that leaving them exposed to the elements, both rain and cold, led to pseudomonas problems. He recommended sticking with the plugs, but potting into smaller containers, greenhouse kept. There's been a lot of talk in other threads about heavy losses this past winter. My rootstock losses in the past have run 5-10%. Irksome, but not enough of a prod. This last year's losses have me asking for assistance from our Ag service, trying to educate myself on fungal pathogens. I'm pretty clueless in that department.
K4, I have not heard of A.p. 'Heavy Seed' and it's uses for rootstock. Is it similar to the green rootstock used at most nurseries? campbtl, A huge variable in rootstock means that many of your trees might have a weaker root system in their genetics. To me, I prefer as uniform seedlings as I can get which generally have a stronger root system behind them. This past year, my rootstock was unprotected for most of the winter, getting rained and snowed on. I was blessed in that I didn't lose any root stock. Then again, all my rootstock came off of trees grown in the mountains of NC for over 25 years, so they may be a little more use to the climate. Tim
Of course it's hard to judge where exactly a cold spot is. But it seems more likely to me that if a bunch of plants are sitting together, some of the stock freezes and other doesn't, that a likely culprit is variability in stock. I have certainly had some winters where rootstock froze and died but the grafted part was OK, which leads me to believe the top is hardier than the under stock. It concerns me when some of out friends in z5 recommend a plant as hardy, but really it's the understock that may freeze... Or the species: but it's for sure that even within relatively homogeneous populations of palmatum the mutability guarantees there will be many "off men out". Perhaps these are removed prior to sale; but there will still be plants of different vigor, etc. I thought it was common wisdom that vigorous rootstock will effect the behavior of dwarf plants, and the other way around. E.g. in the apple world, "dwarfing rootstock" is used to limit the growth of the grafted top, including shorted nodal lengths, which can pack more spurs per branch length. Since many of these "work" simply by providing more or less food to the graft, it makes sense that heavy fertilization would lead to the long internodes, and by putting a dwarf on vigorous under stock and adding lots of food, you could get it to behave in a very different way. I've always assumed that was the story (well, as misidentifications) with the "my dwarf isn't a dwarf" threads we see every once in a while. -E
Dwarfing rootstock - have never seen it offered for japanese maples, so I don't know if it exists. I've heard of it for apple trees though.
